Liquid Biopsy: A Multi-Parametric Analysis of Mutation Status, Circulating Tumor Cells and Inflammatory Markers in EGFR-Mutated NSCLC

The liquid biopsy has the potential to improve patient care in the diagnostic and therapeutic setting in non-small cell lung cancer (NSCLC). Consented patients with epidermal growth factor receptor (EGFR) positive disease (n = 21) were stratified into two cohorts: those currently receiving EGFR tyrosine kinase inhibitor (TKI) therapy (n = 9) and newly diagnosed EGFR TKI treatment-naïve patients (n = 12). Plasma genotyping of cell-free DNA was carried out using the FDA-approved cobas® EGFR mutation test v2 and compared to next generation sequencing (NGS) cfDNA panels. Circulating tumor cell (CTC) numbers were correlated with treatment response and EGFR exon 20 p.T790M. The prognostic significance of the neutrophil to lymphocyte ratio (NLR) and lactate dehydrogenase (LDH) was also investigated. Patients in cohort 1 with an EGFR exon 20 p.T790M mutation progressed more rapidly than those with an EGFR sensitizing mutation, while patients in cohort 2 had a significantly longer progression-free survival (p = 0.04). EGFR exon 20 p.T790M was detected by liquid biopsy prior to disease progression indicated by computed tomography (CT) imaging. The cobas® EGFR mutation test detected a significantly greater number of exon 20 p.T790M mutations (p = 0.05). High NLR and derived neutrophil to lymphocyte ratio (dNLR) were associated with shorter time to progression and worse survival outcomes (p < 0.05). High LDH levels were significantly associated with shorter time to disease progression (p = 0.03). These data support the use of liquid biopsy for monitoring EGFR mutations and inflammatory markers as prognostic indicators in NSCLC.

Abstract 3354: A gene expression signature of high serum cholesterol and prostate cancer outcomes

Statin use is associated with reduced risk of lethal prostate cancer potentially through effects on serum cholesterol. Using data from a prospective study with measured serum cholesterol among men subsequently diagnosed with prostate cancer, we developed a tumour gene expression score to reflect the pre-diagnosis serum cholesterol environment these tumours developed in, and applied this score to a separate study to examine the relationship with prostate cancer-specific outcomes. We identified 127 men with prostate cancer in the prospective Health Professionals Follow-up Study, whose prostate tumors underwent whole genome gene expression profiling. Pre-diagnosis serum cholesterol was measured a median of 3.3 years (IQR 1.5-4.8 years) prior to cancer diagnosis. We excluded men using statins either at time of blood draw for serum cholesterol measurement or at cancer diagnosis. Using tumor biopsy whole genome transcriptomic data from 232 prostate cancer patients treated with radiotherapy in Northern Ireland (NI), we generated the serum cholesterol score by summing z-score-transformed expression for each gene. PTEN status was measured using a published 50-gene transcriptional signature. Both signatures were dichotomized using the median cut-point. Age-adjusted and multivariable Cox regression analysis was used to compute HRs and 95% CI for associations of the cholesterol gene score with biochemical recurrence and metastasis risk. We identified in HPFS a set of 30 genes associated with pre-diagnostic serum cholesterol with a fold change ≥4 which included PTEN. In the NI Cohort, tumors with above median cholesterol scores had higher expression of the PTEN-null signature (p&lt;0.001). Increased serum cholesterol tumor score was associated with higher Gleason grade (p&lt;0.001); this relationship was stronger in PTEN-null tumours relative to PTEN-intact. Over a median follow-up of 11 years, 68 men experienced biochemical recurrence, and 28 developed metastasis. In age-adjusted analysis, patients with high serum cholesterol score had increased risk of recurrence (HR 1.84; 95% CI 1.13-2.99) and metastasis (HR 1.98; 95% CI 0.91-4.29), though the latter was not statistically significant. Associations with recurrence and metastasis were attenuated following further adjustment for Gleason score (HR 1.65; 95% CI, 0.98-2.77 and HR 1.49; 95% CI 0.66-3.35, respectively). Men with increased tumor gene expression of a serum cholesterol score, derived to reflect tumor development within a high serum cholesterol environment, were more likely to be diagnosed with a PTEN-null prostate cancer. These men had more aggressive prostate cancer at diagnosis and increased risk of recurrence, particularly men with PTEN-null disease. Our results support recent findings showing a reduced risk of PTEN-null prostate cancer in statin users, and inform our understanding of the potential role of serum cholesterol in prostate cancer etiology.

Citation Format: Sarah Jane Winter, Sophia R. Halliday, Travis A. Gerke, Lorelei Ann Mucci, Konrad H. Stopsack, Gillian Prue, Suneil Jain, Emma H. Allott. A gene expression signature of high serum cholesterol and prostate cancer outcomes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3354.

Statins and prostate cancer-hype or hope? The epidemiological perspective

BACKGROUND

Men using cholesterol-lowering statin medications have been found to have lower risks of both advanced and fatal prostate cancer in multiple registry-based studies and prospective cohort studies. Statin use has also been associated with longer survival among men already diagnosed with prostate cancer. Mechanisms responsible for purported anti-cancer effects of statins are not well understood but may offer insight into prostate cancer biology.

METHODS

We summarise epidemiological data from studies of statins and prostate cancer and discuss to what extent these findings can be interpreted as causal. Additionally, lipid-mediated and non-lipid-mediated mechanisms that may contribute to potential anti-cancer effects of statins are reviewed. Finally, we consider treatment settings and molecular subgroups of men who might benefit more than others from statin use in terms of prostate cancer-specific outcomes.

RESULTS

Data from prospective observational studies generally reported a lower risk of fatal prostate cancer among statin users. There is some evidence for serum cholesterol-lowering as an indirect mechanism linking statins with advanced and fatal prostate cancer. Window-of-opportunity clinical trials show measurable levels of statins in prostate tissue highlighting potential for direct effects, whilst observational data suggest possible statin-driven modulation of prostate microenvironment inflammation. Additionally, emerging data from registry studies support a potential role for statins within the context of androgen deprivation therapy and anti-androgen treatment.

CONCLUSION

Prospective and registry-based studies support a lower risk of advanced and fatal prostate cancer in statin users relative to non-users, as well as better outcomes among prostate cancer patients. The few randomised-controlled trials conducted so far have short follow-up, lack identified molecular subgroups, and do not provide additional support for the observational results. Consequently, additional evidence is required to determine which men may experience greatest benefit in terms of prostate cancer-specific outcomes and how statin effects may vary according to molecular tumour characteristics.

Long non-coding RNAs and their potential impact on diagnosis, prognosis, and therapy in prostate cancer: racial, ethnic, and geographical considerations

INTRODUCTION

Advances in high-throughput sequencing have greatly advanced our understanding of long non-coding RNAs (lncRNAs) in a relatively short period of time. This has expanded our knowledge of cancer, particularly how lncRNAs drive many important cancer phenotypes via their regulation of gene expression.

AREAS COVERED

Men of African descent are disproportionately affected by PC in terms of incidence, morbidity, and mortality. LncRNAs could serve as biomarkers to differentiate low-risk from high-risk diseases. Additionally, they may represent therapeutic targets for advanced and castrate-resistant cancer. We review current research surrounding lncRNAs and their association with PC. We discuss how lncRNAs can provide new insights and diagnostic biomarkers for African American men. Finally, we review advances in computational approaches that predict the regulatory effects of lncRNAs in cancer.

EXPERT OPINION

PC diagnostic biomarkers that offer high specificity and sensitivity are urgently needed. PC specific lncRNAs are compelling as diagnostic biomarkers owing to their high tissue and tumor specificity and presence in bodily fluids. Recent studies indicate that PCA3 clinical utility might be restricted to men of European descent. Further work is required to develop lncRNA biomarkers tailored for men of African descent.

Characterizing and Exploiting Tumor Microenvironments to Optimize Treatment Outcomes

Simple Summary

The Irish Association for Cancer Research (IACR) held its 57th annual conference from the 24–26 March 2021 in a virtual format due to the ongoing pandemic. This report provides a summary overview of the work presented at the conference, which had a particular focus on the tumor microenvironment. Tumors do not develop and grow in isolation, but rather within the context of their surrounding environment. The work presented at the conference outlined the complexity of the tumor microenvironment and highlighted several ways in which it influences tumor growth and progression. Moreover, the tumor microenvironment was discussed as a potential target for new cancer treatments. Traditionally, laboratory research has focused on the tumor only, but conference speakers highlighted the importance of modeling the surrounding microenvironment to gain a more physiologically relevant view of tumorigenesis. Finally, conference attendees heard from the patient’s perspective regarding the development of novel targeted therapies.

Abstract

Our understanding of cancer initiation, progression, and treatment is continually progressing through dedicated research achieved through laboratory investigation, clinical trials, and patient engagement. The importance and complexity of the microenvironment and its role in tumor development and behavior is pivotal to the understanding of tumor growth and the best course of treatment. The 57th Irish Association for Cancer Research (IACR) Annual Conference collected key researchers, clinicians, and patient advocates together to highlight and discuss the recognized importance of the microenvironment and treatment advances in cancer. In this article, we describe the key components of the microenvironment that influence tumor development and treatment, including the microbiome, metabolism, and immune response and the progress of preclinical models to reflect these complex environments. From a psycho-social oncology perspective, we highlight expert opinion and data on the process of shared decision-making in the context of emerging cancer treatments.

Abstract 162: Cholesterol metabolism gene expression and prostate cancer-specific outcomes in radiotherapy-treated patients

Introduction Dysregulated lipid metabolism is a hallmark of prostate cancer. Furthermore, use of the cholesterol lowering statin drugs has been linked to a reduced risk of lethal prostate cancer. To understand the molecular pathways implicated in this relationship, we examined the association between differential expression of genes involved in intratumoral cholesterol metabolism in prostate tumor biopsies and prostate cancer-specific outcomes.

Methods Tumor biopsy gene expression data from 242 men diagnosed with localized/locally advanced prostate cancer and treated with radiotherapy and androgen deprivation therapy was analyzed. A total of 71 genes involved in cholesterol transport, biosynthesis and regulation were selected from the Reactome pathway database, with additional genes involved in cholesterol metabolism extracted from literature. For each gene, expression levels were dichotomized by median expression level. Cox proportional hazards regression was used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for associations of gene expression with biochemical recurrence and metastasis. Models were adjusted for age at diagnosis and Gleason score. Multiple-testing correction was performed using the Bonferroni correction method.

Results During a median follow-up of 10.4 years, 72 (30%) patients experienced biochemical recurrence and 32 (13%) developed metastatic disease. Differential expression of several genes was found to be associated with risk of biochemical recurrence and metastasis, though none remained statistically significant following Bonferroni correction. However, several genes showed similar patterns of association with risk of biochemical recurrence and of metastasis, an association which remained similar following adjustment for age and Gleason score. Low (below median) expression of FDFT1, a gene encoding squalene synthase, a key enzyme in cholesterol biosynthesis, was associated with an increased risk of biochemical recurrence (HR 1.87; 95% CI, 1.15-3.01) and metastasis (HR 3.52; 95% CI, 1.52-8.16). High (above median) expression of SLCO1B3, a gene encoding an organic anion transporting polypeptide transporting a variety of small molecules including statins, was associated with higher risk of biochemical recurrence (HR 2.14; 95% CI, 1.31-3.49) and metastasis (HR 2.70; 95% CI, 1.25-5.90).

Conclusion These hypothesis-generating results point to a potential role for altered intratumoral cholesterol metabolism in prostate cancer-specific outcomes. Our findings highlighting differential expression of FDFT1 and SLCO1B3, genes involved in cholesterol biosynthesis and anion transport, respectively, in association with risk of biochemical recurrence and metastasis may provide clues as to the mechanistic pathways of most importance. Validation in other prostate cancer gene expression datasets is required.

Citation Format: Sarah J. Winter, Sophia Halliday, Konrad H. Stopsack, Sarah O. Osman, Alan R. Hounsell, Gillian Prue, Suneil Jain, Emma H. Allott. Cholesterol metabolism gene expression and prostate cancer-specific outcomes in radiotherapy-treated patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 162.

Borderline Estrogen Receptor-Positive Breast Cancers in Black and White Women

BACKGROUND

Some breast tumors expressing greater than 1% and less than 10% estrogen receptor (ER) positivity (ER-borderline) are clinically aggressive; others exhibit luminal biology. Prior ER-borderline studies included few black participants.

METHODS

Using the Carolina Breast Cancer Study (phase I: 1993-1996; 2: 1996-2001; 3: 2008-2013), a population-based study that oversampled black women, we compared ER-borderline (n = 217) to ER-positive (n = 1885) and ER-negative (n = 757) tumors. PAM50 subtype and risk of recurrence score (ROR-PT, incorporates subtype, proliferation, tumor size) were measured. Relative frequency differences (RFD) were estimated using multivariable linear regression. Disease-free interval (DFI) was evaluated by ER category and endocrine therapy receipt, overall and by race, using Kaplan Meier and Cox models. Statistical tests were two-sided.

RESULTS

ER-borderlines were more frequently basal-like (RFD = +37.7%, 95% confidence interval [CI] = 27.1% to 48.4%) and high ROR-PT (RFD = +52.4%, 95% CI = 36.8% to 68.0%) relative to ER-positives. Having a high ROR-PT ER-borderline tumor was statistically significantly associated with black race (RFD = +26.2%, 95% CI = 9.0% to 43.3%). Compared to ER-positives, DFI of ER-borderlines treated with endocrine therapy was poorer but not statistically significantly different (hazard ratio [HR] = 2.03, 95% CI = 0.89% to 4.65%), whereas DFI was statistically significantly worse for ER-borderlines without endocrine therapy (HR = 3.33, 95% CI = 1.84% to 6.02%). However, black women with ER-borderline had worse DFI compared to ER-positives, even when treated with endocrine therapy (HR = 2.77, 95% CI = 1.09% to 7.04%).

CONCLUSIONS

ER-borderline tumors were genomically heterogeneous, with survival outcomes that differed by endocrine therapy receipt and race. Black race predicted high-risk ER-borderlines and may be associated with poorer endocrine therapy response.

Epidemiology of Basal-like and Luminal Breast Cancers among Black Women in the AMBER Consortium

BACKGROUND

Evidence suggests etiologic heterogeneity among breast cancer subtypes. Previous studies with six-marker IHC classification of intrinsic subtypes included small numbers of black women.

METHODS

Using centralized laboratory results for estrogen receptor (ER), progesterone receptor, HER2, proliferation marker, Ki-67, EGFR, and cytokeratin (CK)5/6, we estimated case-only and case-control ORs for established breast cancer risk factors among cases (n = 2,354) and controls (n = 2,932) in the African American Breast Cancer Epidemiology and Risk (AMBER) consortium. ORs were estimated by ER status and intrinsic subtype using adjusted logistic regression.

RESULTS

Case-only analyses by ER status showed etiologic heterogeneity by age at menarche, parity (vs. nulliparity), and age at first birth. In case-control analyses for intrinsic subtype, increased body mass index and waist-to-hip ratio (WHR) were associated with increased risk of luminal A subtype, whereas older age at menarche and parity, regardless of breastfeeding, were associated with reduced risk. For basal-like cancers, parity without breastfeeding and increasing WHR were associated with increased risk, whereas breastfeeding and age ≥25 years at first birth were associated with reduced risk among parous women. Basal-like and ER^-/HER2⁺ subtypes had earlier age-at-incidence distribution relative to luminal subtypes.

CONCLUSIONS

Breast cancer subtypes showed distinct etiologic profiles in the AMBER consortium, a study of more than 5,000 black women with centrally assessed tumor biospecimens.

IMPACT

Among black women, high WHR and parity without breastfeeding are emerging as important intervention points to reduce the incidence of basal-like breast cancer.

Platelet cloaking of circulating tumour cells in patients with metastatic prostate cancer: Results from ExPeCT, a randomised controlled trial

Background

Circulating tumour cells (CTCs) represent a morphologically distinct subset of cancer cells, which aid the metastatic spread. The ExPeCT trial aimed to examine the effectiveness of a structured exercise programme in modulating levels of CTCs and platelet cloaking in patients with metastatic prostate cancer.

Methods

Participants (n = 61) were randomised into either standard care (control) or exercise arms. Whole blood was collected for all participants at baseline (T0), three months (T3) and six months (T6), and analysed for the presence of CTCs, CTC clusters and platelet cloaking. CTC data was correlated with clinico-pathological information.

Results

Changes in CTC number were observed within group over time, however no significant difference in CTC number was observed between groups over time. Platelet cloaking was identified in 29.5% of participants. A positive correlation between CTC number and white cell count (WCC) was observed (p = 0.0001), in addition to a positive relationship between CTC clusters and PSA levels (p = 0.0393).

Conclusion

The presence of platelet cloaking has been observed in this patient population for the first time, in addition to a significant correlation between CTC number and WCC.

Trial registration

ClincalTrials.gov identifier NCT02453139.

Sleep quality and prostate cancer aggressiveness: Results from the REDUCE trial

BACKGROUND

Disrupted sleep has been associated with increased risk of certain cancers. Little data exist in prostate cancer. We tested the association between sleep quality and prostate cancer diagnosis overall and by tumor grade in the Reduction by Dutasteride of Prostate Cancer Events chemoprevention trial. We hypothesized that worse sleep quality would be associated with increased tumor aggressiveness.

METHODS

At baseline, 5614 men completed a validated six-item questionnaire on sleep quality. We generated a composite score categorized into tertiles to measure overall sleep quality and assessed each sleep quality question individually. Logistic regression was used to test associations between baseline sleep quality and overall, low-grade and high-grade prostate cancer diagnosis at 2-year study-mandated biopsy. Models were stratified by nocturia.

RESULTS

Overall sleep quality was unrelated to overall or low-grade prostate cancer. Worse overall sleep quality was associated with elevated odds of high-grade prostate cancer (odds ratio [OR]_T3vsT1 1.15; 95% confidence interval [CI]: 0.83-1.60 and OR_T2vsT1 1.39; 95% CI: 1.01-1.92). Men reporting trouble falling asleep at night sometimes vs never had elevated odds of high-grade prostate cancer (OR: 1.51; 95% CI: 1.08-2.09) while trouble staying awake during the day was associated with decreased odds of low-grade prostate cancer (OR: 0.65; 95% CI: 0.49-0.86). Results were similar within strata of nocturia severity.

CONCLUSIONS

Overall, associations between sleep quality and prostate cancer were inconsistent. However, there was some evidence for a positive association between insomnia and high-grade prostate cancer, and an inverse relationship between daytime sleepiness and low-grade prostate cancer; findings that should be validated by future studies.

Abdominal and pelvic adipose tissue distribution and risk of prostate cancer recurrence after radiation therapy

BACKGROUND

Fat distribution varies between individuals of similar body mass index (BMI). We hypothesized that visceral obesity is more strongly associated with poor prostate cancer outcomes than overall obesity defined by BMI.

MATERIALS AND METHODS

We quantified abdominal visceral and subcutaneous fat area (VFA and SFA), and pelvic periprostatic adipose tissue area (PPAT), using computed tomography scans from radiation-treated prostate cancer patients at the Durham North Carolina Veterans Administration Hospital. Multivariable-adjusted Cox regression examined associations between each adiposity measure and risk of recurrence, overall and stratified by race and receipt of androgen deprivation therapy (ADT).

RESULTS

Of 401 patients (59% black) treated from 2005 to 2011, 84 (21%) experienced recurrence during 9.3 years median follow-up. Overall, obesity defined by BMI was not associated with recurrence risk overall or stratified by race or ADT, nor was any measure of fat distribution related to the risk of recurrence overall or by race. However, higher VFA was associated with increased risk of recurrence in men who received radiation only (hazard ratio [HR], 1.79; 95% confidence interval [CI], 0.87-3.66), but inversely associated with recurrence risk in men treated with radiation and ADT (HR, 0.49; 95% CI, 0.24-1.03; P-interaction = .002), though neither association reached statistical significance. Similar patterns of ADT-stratified associations were observed for PPAT and SFA.

CONCLUSIONS

Associations between abdominal and pelvic adiposity measures and recurrence risk differed significantly by ADT receipt, with positive directions of association observed only in men not receiving ADT. If confirmed, our findings suggest that obesity may have varying effects on prostate cancer progression risk dependent on the hormonal state of the individual.

Asian Race and Risk of Prostate Cancer: Results from the REDUCE Study

BACKGROUND

Global prostate cancer incidence rates are lower in Asian men than Caucasian men. Whether this is the result of less screening in Asian men remains to be determined. We examined whether Asian race was associated with prostate cancer diagnosis in the Reduction by Dutasteride of Cancer Events (REDUCE) study.

METHODS

REDUCE was a 4-year, multicenter, randomized trial of dutasteride versus placebo for prostate cancer prevention among men who underwent prostate-specific antigen (PSA)-independent biopsies at 2 and 4 years. Eligible men were ages 50 to 75 years, had PSA between 2.5 and 10 ng/mL, and a negative prestudy prostate biopsy. We tested the association between Asian and Caucasian race and prostate cancer diagnosis using logistic regression.

RESULTS

Of 8,122 men in REDUCE, 5,755 (71%) were Caucasian and 105 (1.8%) were Asian. Asians had lower body mass index (24.8 vs. 26.9 kg/m², P < 0.001), had smaller prostate volume (35.0 vs. 43.5 cc, P < 0.001), and were less likely to have abnormal digital rectal exams (P = 0.048), but were similar in baseline age, PSA, family history of prostate cancer, and smoking status compared with Caucasian men (all P ≥ 0.164). Asian men were equally likely to receive any on-study biopsy compared with Caucasian men (P = 0.634). After adjusting for potential confounders, Asian men were less likely to be diagnosed with prostate cancer during the 4-year study (OR = 0.49; 95% confidence interval, 0.28-0.88; P = 0.016), compared with Caucasian men.

CONCLUSIONS

In REDUCE, where all men underwent biopsies largely independent of PSA, Asian race was associated with lower prostate cancer diagnosis.

IMPACT

These findings suggest that lower prostate cancer risk in Asian men may be due to biological, genetic, and/or lifestyle factors.

Statin Use Is Associated with Lower Risk of PTEN-Null and Lethal Prostate Cancer

PURPOSE

Statins are associated with lower risk of aggressive prostate cancer, but lethal prostate cancer is understudied and contributing mechanisms are unclear. We prospectively examined statins and lethal prostate cancer risk in the Health Professionals Follow-up Study (HPFS), tested associations with molecular subtypes, and integrated gene expression profiling to identify putative mechanisms.

EXPERIMENTAL DESIGN

Our study included 44,126 men cancer-free in 1990, followed for prostate cancer incidence through 2014, with statin use recorded on biennial questionnaires. We used multivariable Cox regression to examine associations between statins and prostate cancer risk overall, by measures of clinically significant disease, and by ERG and PTEN status. In an exploratory analysis, age-adjusted gene set enrichment analysis identified statin-associated pathways enriched in tumor and adjacent normal prostate tissue.

RESULTS

During 24 years of follow-up, 6,305 prostate cancers were diagnosed and 801 (13%) were lethal (metastatic at diagnosis or metastatic/fatal during follow-up). Relative to never/past use, current statin use was inversely associated with risk of lethal prostate cancer [HR, 0.76; 95% confidence interval (CI), 0.60-0.96] but not overall disease. We found a strong inverse association for risk of PTEN-null cancers (HR, 0.40; 95% CI, 0.19-0.87) but not PTEN-intact cancers (HR, 1.18; 95% CI, 0.95-1.48; P heterogeneity = 0.01). Associations did not differ by ERG. Inflammation and immune pathways were enriched in normal prostate tissue of statin ever (n = 10) versus never users (n = 103).

CONCLUSIONS

Molecular tumor classification identified PTEN and inflammation/immune activation as potential mechanisms linking statins with lower lethal prostate cancer risk. These findings support a potential causal association and could inform selection of relevant biomarkers for statin clinical trials.

Bimodal age distribution at diagnosis in breast cancer persists across molecular and genomic classifications

PURPOSE

Female breast cancer demonstrates bimodal age frequency distribution patterns at diagnosis, interpretable as two main etiologic subtypes or groupings of tumors with shared risk factors. While RNA-based methods including PAM50 have identified well-established clinical subtypes, age distribution patterns at diagnosis as a proxy for etiologic subtype are not established for molecular and genomic tumor classifications.

METHODS

We evaluated smoothed age frequency distributions at diagnosis for Carolina Breast Cancer Study cases within immunohistochemistry-based and RNA-based expression categories. Akaike information criterion (AIC) values compared the fit of single density versus two-component mixture models. Two-component mixture models estimated the proportion of early-onset and late-onset categories by immunohistochemistry-based ER (n = 2860), and by RNA-based ESR1 and PAM50 subtype (n = 1965). PAM50 findings were validated using pooled publicly available data (n = 8103).

RESULTS

Breast cancers were best characterized by bimodal age distribution at diagnosis with incidence peaks near 45 and 65 years, regardless of molecular characteristics. However, proportional composition of early-onset and late-onset age distributions varied by molecular and genomic characteristics. Higher ER-protein and ESR1-RNA categories showed a greater proportion of late age-at-onset. Similarly, PAM50 subtypes showed a shifting age-at-onset distribution, with most pronounced early-onset and late-onset peaks found in Basal-like and Luminal A, respectively.

CONCLUSIONS

Bimodal age distribution at diagnosis was detected in the Carolina Breast Cancer Study, similar to national cancer registry data. Our data support two fundamental age-defined etiologic breast cancer subtypes that persist across molecular and genomic characteristics. Better criteria to distinguish etiologic subtypes could improve understanding of breast cancer etiology and contribute to prevention efforts.

Evidence for Etiologic Subtypes of Breast Cancer in the Carolina Breast Cancer Study

BACKGROUND

Distinctions in the etiology of triple-negative versus luminal breast cancer have become well established using immunohistochemical surrogates [notably estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2)]. However, it is unclear whether established immunohistochemical subtypes are the sole or definitive means of etiologically subdividing breast cancers.

METHODS

We evaluated clinical biomarkers and tumor suppressor p53 with risk factor data from cases and controls in the Carolina Breast Cancer Study, a population-based study of incident breast cancers. For each individual marker and combinations of markers, we calculated an aggregate measure to distinguish the etiologic heterogeneity of different classification schema. To compare schema, we estimated subtype-specific case-control odds ratios for individual risk factors and fit age-at-incidence curves with two-component mixture models. We also evaluated subtype concordance of metachronous contralateral breast tumors in the California Cancer Registry.

RESULTS

ER was the biomarker that individually explained the greatest variability in risk factor profiles. However, further subdivision by p53 significantly increased the degree of etiologic heterogeneity. Age at diagnosis, nulliparity, and race were heterogeneously associated with ER/p53 subtypes. The ER-/p53+ subtype exhibited a similar risk factor profile and age-at-incidence distribution to the triple-negative subtype.

CONCLUSIONS

Clinical marker-based intrinsic subtypes have established value, yet other schema may also yield important etiologic insights.

IMPACT

Novel environmental or genetic risk factors may be identifiable by considering different etiologic schema, including cross-classification based on ER/p53.

Statin use and longitudinal changes in prostate volume; results from the REduction by DUtasteride of prostate Cancer Events (REDUCE) trial

OBJECTIVE

To test the association between statin use and prostate volume (PV) change over time using data from the REduction by DUtasteride of prostate Cancer Events (REDUCE) trial, a 4-year randomised controlled trial testing dutasteride for prostate cancer chemoprevention.

SUBJECTS/PATIENTS AND METHODS

We identified men with a baseline negative prostate biopsy from REDUCE who did not undergo prostate surgery or develop prostate cancer over the trial period. Men reported statin use at baseline. PV was determined from transrectal ultrasonography performed to guide prostate biopsy at baseline, and 2- and 4-years after randomisation. Multivariable generalised estimating equations tested differences in PV change over time by statin use, overall and stratified by treatment arm. We tested for interactions between statins and time in association with PV using the Wald test.

RESULTS

Of 4106 men, 17% used statins at baseline. Baseline PV did not differ by statin use. Relative to non-users, statin users had decreasing PVs over the trial period (P = 0.027). Similar patterns were seen in the dutasteride and placebo arms, although neither reached statistical significance. The mean estimated PV was modestly but significantly lower in statin users relative to non-users in the dutasteride arm at 2-years (4.5%, P = 0.032) and 4-years (4.0%, P = 0.033), with similar (3-3.3%) but non-significant effects in the placebo arm.

CONCLUSION

If confirmed, our present findings support a role for statins in modestly attenuating PV growth, with a magnitude of effect in line with previously reported prostate-specific antigen-lowering effects of statins (~4%). Future studies are needed to assess whether this putative role for statins in PV growth could impact lower urinary tract symptom development or progression.

Intratumoral Sterol-27-Hydroxylase (CYP27A1) Expression in Relation to Cholesterol Synthesis and Vitamin D Signaling and Its Association with Lethal Prostate Cancer

BACKGROUND

Higher intratumoral cholesterol synthesis is associated with a worse prognosis in prostate cancer. The vitamin D-regulated enzyme sterol-27-hydroxylase (CYP27A1) converts cholesterol to 27-hydroxycholesterol, potentially lowering intracellular cholesterol levels. We hypothesized that low CYP27A1 expression is associated with high cholesterol synthesis, low vitamin D signaling, and higher risk of lethal prostate cancer.

METHODS

In 404 patients from the prospective prostate cancer cohorts within the Health Professionals Follow-up Study (HPFS) and the Physicians' Health Study (PHS), we assessed intratumoral CYP27A1 expression and proxies of cholesterol synthesis using transcriptome profiling, prediagnostic plasma 25-hydroxyvitamin D [25(OH)D; n = 132], and intratumoral vitamin D receptor protein expression (VDR; n = 300). Patients were followed for metastases and prostate cancer mortality (lethal cancer; median follow-up, 15.3 years).

RESULTS

CYP27A1 expression was lower in tumors with higher Gleason grade and higher expression of cholesterol synthesis enzymes, including the second rate-limiting enzyme, SQLE. We did not detect consistent associations between CYP27A1 and 25(OH)D, VDR, or CYP24A1 mRNA expression. Lower CYP27A1 was associated with higher risk of lethal cancer in both cohorts, independent of SQLE [adjusted OR for lowest vs. highest quartile of CYP27A1, 2.64; 95% confidence interval (CI), 1.24-5.62]. This association was attenuated when additionally adjusting for Gleason grade (OR, 1.76; 95% CI, 0.75-4.17).

CONCLUSIONS

Low CYP27A1 expression was associated with higher cholesterol synthesis and a higher risk of lethal disease.

IMPACT

These observations further support the hypothesis that intratumoral cholesterol accumulation through higher synthesis and decreased catabolism is a feature of lethal prostate cancer.

Abstract P1-09-05: Clinical and genomic characteristics of borderline ER-positive breast cancers

Background: Though current guidelines classify breast tumors with ≥1% estrogen receptor (ER) positivity by immunohistochemistry as ER positive, “borderline” tumors expressing ≥1 – &lt;10% positivity have biological similarities to ER negative tumors in prior studies. We sought to describe molecular features of ER-borderline breast cancer in a diverse cohort of incident cases and identify characteristics associated with high-risk borderline tumors.

Methods: We used the Carolina Breast Cancer Study, a large population-based study that oversampled young and black women in 44 counties of North Carolina, to study characteristics of ER-borderline cases compared to other ER-positive and ER-negative tumors. Gene expression of ESR1, PAM50 subtype, and risk of recurrence score (ROR-PT, calculated from subtype, proliferation level, and tumor size; categorized as low, medium, high) were quantified using RNA counting methods, with finite mixture modeling to establish a cutoff for ESR1-high vs. -low tumors. The relative frequency differences of clinical and genomic features of borderline vs. positive/negative tumors were estimated using linear regression, adjusted for age and race. Recurrence risk was evaluated by ER status, with and without receipt of endocrine therapy using Kaplan-Meier curves and Cox proportional hazards models.

Results: Of 2,859 eligible patients, 8% (n=217) were ER borderline, 26% (n=757) were ER negative and 66% were ER positive. Compared to other ER positive tumors (which were 5% basal-like, 89% luminal, 8% high ROR-PT, 16% ESR1-low), borderlines (40% basal-like, 42% luminal, 26% high ROR-PT, 71% ESR1-low) had a higher relative frequency of basal-like subtype (+37.7%, 95% CI 27.1, 48.4), high ROR-PT (+52.4%, 95% CI 36.8, 68.0), and ESR1-low status (+26.3%, 95% CI 20.2, 32.5). In log-rank analysis, recurrence risk in borderlines was not significantly different from ER negatives. However, after adjusting for patient and tumor factors, recurrence risk in borderlines treated without endocrine therapy was the highest of all subtypes (HR 2.9, 95% CI 1.6, 5.0) and persisted after further adjusting for ROR-PT. Results are summarized in Table 1. Frequency of high ROR-PT was 22% among white women with borderline tumors but was significantly more common among black women with borderline tumors (+26.0%, 95% CI 7.1, 45.0). Among borderlines, high grade was associated with basal-like subtype (+43.4%, 95% CI 18.7, 68.0; reference = non-basal subtype, 52% high grade).

Table 1:Recurrence-free survival by ER subtype and endocrine therapy receipt Hazard Ratio (HR) Model 1HR Model 2ER PositiveREFREFER Borderline, no endocrine therapy2.9 (1.6, 5.0)2.3 (1.1, 4.9)ER Borderline, endocrine therapy1.5 (0.7, 3.2)1.5 (0.6, 3.7)ER Negative1.8 (1.3, 2.6)1.5 (0.9, 2.4)Adjusted for (1) age, race, stage, grade, year of diagnosis, (2) variables in (1) and ROR-PT

Conclusion: Consistent with prior studies, borderline tumors demonstrated characteristics that were intermediate between other ER positive and negative tumors, with heterogeneity of genomic features. Given the higher recurrence risk among borderlines, identifying aggressive borderline tumors is important. Black women and those with high tumor grade may benefit from further genomic assessment to guide treatment decisions.

Citation Format: Benefield HC, Allott EH, Sun X, Reeder-Hayes KE, Troester MA. Clinical and genomic characteristics of borderline ER-positive breast cancers [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-09-05.

Abstract A015: Molecular tumor profiling to identify mechanisms linking statin use with lower risk of lethal prostate cancer: Results from the Health Professionals Follow-up Study

Introduction: Epidemiologic data support an inverse association between statin use and risk of lethal prostate cancer, but contributing mechanisms have not been elucidated. Herein, using data from the Health Professionals Follow-up Study (HPFS), we updated our previous analysis of statins and lethal prostate cancer with a decade of additional follow-up, and incorporated immunohistochemistry (IHC)-based biomarkers and gene expression profiling to identify putative molecular mechanisms contributing to the association.

Methods: We included data from 44,076 HPFS participants who were cancer free in 1990, with follow-up through 2012. Participants reported prediagnostic statin use on biennial questionnaires. Statin use was categorized as current vs. never/past use, with current users further categorized as long-term vs. short-term users (≥6 vs. &lt;6 years). To classify prostate cancer molecular subtypes, genetically validated IHC assays for TMPRSS2:ERG fusion and PTEN loss were conducted on tissue microarrays for 891 and 660 cases, respectively. Whole-genome mRNA profiling of tumor and adjacent normal tissue was completed for 237 and 114 cases, respectively, using Affymetrix GeneChip Human Gene 1.0 ST arrays. We used Cox proportional hazards analysis to generate hazard ratios (HR) and 95% confidence intervals (CI) for associations between statin use and risk of overall, advanced (stage T3b or higher at diagnosis, metastatic or fatal), and lethal (metastatic or fatal) prostate cancer, as well as molecular subtypes, adjusted for PSA testing behavior and potential confounders including obesity and smoking. Moreover, we explored gene expression pathways in tumor and adjacent normal prostate tissue of statin users vs. nonusers using gene set enrichment analysis (GSEA).

Results: During 22 years of follow-up, 6,144 men were diagnosed with prostate cancer; 1,051 (17%) had advanced disease and 827 (13%) developed lethal prostate cancer. Of cases with molecular subtype available, 48% were ERG-positive and 14% PTEN-null. In multivariable analysis, relative to never/past use, current statin use was inversely associated with risk of advanced (HR 0.84; 95% CI 0.68-1.04) and lethal (HR 0.78; 95% CI 0.68-1.01) prostate cancer. These associations were more pronounced in long-term users, where ≥6 years of prediagnosis statin use was significantly associated with a lower risk of advanced (HR 0.72; 95% CI 0.53-0.97) and lethal prostate cancer (HR 0.64; 95% CI 0.45-0.92), relative to nonuse. Long-term statin use was not associated with overall prostate cancer risk, whether ERG-positive (HR 0.89; 95% CI 0.59-1.35) or ERG-negative (HR 1.06; 95% CI 0.74-1.50). However, relative to nonuse, a longer duration of prediagnosis statin use was associated with reduced risk of PTEN-null cancers (HR 0.42; 95% CI 0.20-0.90), but not PTEN-intact disease (HR 1.18; 95% CI 0.95-1.46; p-heterogeneity=0.01). In GSEA, we identified T cell, B cell, and phosphatidylinositol (PI3K) signaling among the top pathways enriched in tumor-adjacent normal prostate tissue of current statin users, relative to never users. Intriguingly, no gene sets were differentially expressed by statin use in the tumor.

Discussion: Our updated findings from the HPFS are consistent with our prior findings and other epidemiologic data supporting a role for statins in lethal prostate cancer prevention. Molecular classification of tumors identified PTEN/PI3K signaling and inflammation/immune activation as two potential mechanisms contributing to this association. Elucidating molecular mechanisms mediating the association between statin use and lower risk of lethal prostate cancer will provide support for a causal effect of statins on lethal prostate cancer risk and could inform statin clinical trials with appropriate intermediate endpoints.

Citation Format: Emma H. Allott, Ericka M. Ebot, Amparo G. Gonzalez-Feliciano, Sarah C. Markt, Kathryn M. Wilson, Thomas U. Ahearn, Travis A. Gerke, Mary K. Downer, Konrad H. Stopsack, Jennifer R. Rider, Stephen J. Freedland, Elizabeth A. Platz, Meir J. Stampfer, Edward L. Giovannucci, Christopher J. Sweeney, Stephen P. Finn, Lorelei A. Mucci. Molecular tumor profiling to identify mechanisms linking statin use with lower risk of lethal prostate cancer: Results from the Health Professionals Follow-up Study [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr A015.

Abstract A057: Examining the link between obesity, inflammation, and exercise in patients with metastatic prostate cancer—An interim analysis from the ExPeCT trial

Background: Globally, prostate cancer (PrCa) is the fourth most common cancer type. Obesity and inflammation have been shown to play significant roles in PrCa disease progression. Obesity and a high body mass index (BMI) are associated with increased PrCa-specific mortality in patients with advanced disease. Furthermore, proinflammatory cytokines can aid metastatic potential and promote angiogenesis. The ExPeCT (Exercise, Prostate Cancer and Circulating Tumor Cells) trial seeks to examine the effectiveness of a structured exercise program in modulating inflammatory mediators and obesity in patients with metastatic PrCa.

Methods: ExPeCT (CTRIALIE 15-21 (ClincalTrials.gov identifier NCT02453139)) is a multicenter, randomized trial for patients with metastatic PrCa (n=67). Participants were randomized to either control or exercise arms. Participants in the exercise arm completed six months of prescribed aerobic exercise, which was monitored using percentage heart-rate reserve. Serum samples were collected for all participants at baseline (T0), three months (T3), and six months (T6), and assayed for 16 interlinked adipokines and cytokines using the Meso Scale Discovery platform. An interim statistical analysis was performed (n=26) comparing median change in serum analyte levels between control (n=13) and exercise (n=13) arms using non-parametric Wilcoxon rank-sum tests.

Results: Among 26 patients included in our interim analysis, mean age at baseline was 71 years, median BMI was 29.1 kg/m2, and median waist circumference (WC) was 107 cm, with no significant differences between arms (all p&gt;0.3). Between T0 and T6, WC decreased by a median of 3.8 cm in the exercise group and 2.6 cm in the control group (p=0.412), with a similar trend for BMI. Interim serum cytokine analysis showed a 3-fold increase in IL-10 levels in the exercise arm at T3 when compared to the control arm (p=0.036). No significant change in IL-10 levels was recorded at T6 between arms (p=0.776). Similarly, CXCL8 (IL-8) levels were increased by 1.8-fold at T3 in the exercise arm in comparison to the control arm (p=0.017), with no significant change reported at T6 (p=0.191). While changes were evident in serum TNFα, IL-6, VEGF, IL-17a, MMP9 and CCL5 (RANTES) levels, these did not reach significance. Differences in levels of adipokines leptin and resistin were also reported. A 1.5-fold increase in resistin expression was observed in the exercise arm at T6; however, it was not significant (p=0.293). A 2-fold decrease in leptin in the control arm relative to the exercise arm at T6 was also detected (p=0.676). Analysis of adiponectin, MMP2, and CCL2 is ongoing.

Conclusion: Our interim analysis of ExPeCT trial participants demonstrated a significant increase in serum CXCL8 and IL-10 levels after three months of a supervised exercise intervention. These preliminary data suggest that a structured exercise program has the potential to modify inflammatory status in patients with metastatic PrCa.

Citation Format: Lauren Brady, Grainne Sheill, Anne-Marie Baird, Emma H. Allott, Tatjana Vlajnic, John Greene, Orla Casey, Brian Hayes, Emer Guinan, Juliette Hussey, Fidelma Cahill, Mieke Van Hemelrijck, Nicola Peat, Sarah Rudman, Moya Cunningham, Liam Grogan, Thomas Lynch, Rustom P. Manecksha, John McCaffrey, Orla Sheils, Dearbhaile M. O’Donnell, John O’Leary, Ray McDermott, Stephen P. Finn. Examining the link between obesity, inflammation, and exercise in patients with metastatic prostate cancer—An interim analysis from the ExPeCT trial [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr A057.

Statin use, high cholesterol and prostate cancer progression; results from HCaP-NC

BACKGROUND

Statin use is associated with lower advanced prostate cancer risk and reduced prostate cancer-specific mortality, but prior studies were conducted mainly in white men. We examined the effect of statin use on risk of prostate cancer progression in a population-based, minority-enriched cohort.

METHODS

We used data from prostate cancer cases (45% African American) diagnosed between 2004 and 2007 who participated in the Health Care Access and Prostate Cancer Treatment in North Carolina cohort (HCaP-NC). We abstracted statin use at diagnosis. Men reported if they had ever been diagnosed with high cholesterol. Multivariable Cox proportional hazards analysis was used to examine associations between statin use and risk of prostate cancer progression (biochemical recurrence or secondary treatment), overall and by race. In secondary analysis, we examined the association between high cholesterol and risk of progression, overall, and by statin use.

RESULTS

Of 669 men, 244 (36%) were statin users at diagnosis. During 3.8 years median follow-up, 138 men experienced prostate cancer progression. There was no association between statin use and risk of progression, either overall (HR 1.03; 95%CI 0.72-1.46) or stratified by race. High cholesterol was inversely associated with risk of progression, particularly among statin users (HR 0.43; 95%CI 0.20-0.94; p-interaction = 0.22) and in men with higher perceived access to care (HR 0.57; 95%CI 0.36-0.90; p-interaction = 0.03). Study limitations included a relatively small sample size, short follow-up, and lack of data regarding post diagnosis statin use.

CONCLUSIONS

Statin use at diagnosis was not associated with prostate cancer progression in the population-based, minority-enriched HCaP-NC. Greater healthcare engagement, including actively controlling serum cholesterol, may be linked to better prostate cancer-specific outcomes.

Abstract 1450: Intratumoral CYP27A1 expression in relation to cholesterol synthesis and vitamin D signaling and its association with lethal prostate cancer

Background: Higher intratumoral cholesterol synthesis is associated with a worse prognosis in prostate cancer. A recent study identified the vitamin D-regulated enzyme CYP27A1, which converts cholesterol to 27-hydroxycholesterol, to negatively affect cholesterol synthesis and to be associated with biochemical recurrence. We hypothesized that low CYP27A1 expression occurs in patients with low vitamin D signaling and high intratumoral cholesterol synthesis, and that low CYP27A1 expression is associated with higher risk of lethal prostate cancer.

Methods: We studied 404 prostate cancer patients in the prospective Health Professionals Follow-up Study (HPFS) and the Physicians' Health Study (PHS) cohorts. After centralized histopathologic review, we measured tumor expression of CYP27A1, SQLE (as a measure of cholesterol synthesis), and CYP24A1 (as a proxy of vitamin D signaling) using mRNA expression profiling. In subgroups, prediagnostic plasma levels of 25-hydroxyvitamin D (25(OH)D, n = 132) and tumor protein expression of the vitamin D receptor (VDR, n = 300) were also available. Using logistic regression, we estimated odds ratios (ORs) for lethal prostate cancer, defined as prostate cancer mortality or metastases, in contrast to non-lethal disease without metastases after at least eight years of follow up.

Results: CYP27A1 expression was weakly positively correlated with expression of the vitamin D target gene CYP24A1 (r = 0.17; p &lt; 0.001) but did not differ by plasma 25(OH)D (p-trend = 0.59) or by VDR expression (p-trend = 0.26). CYP27A1 expression was lower in tumors with higher expression of the second rate-limiting enzyme of cholesterol synthesis, SQLE (r = -0.21; p &lt; 0.001). Tumors with higher Gleason grade had lower CYP27A1 expression (HPFS, p &lt; 0.001; PHS, p = 0.004). Higher CYP27A1 was associated with lower risk of lethal cancer in HPFS (OR for highest vs. lowest quintile of expression, 0.31; 95% CI, 0.13 to 0.73; p-trend = 0.007) and in PHS (OR, 0.10; 95% CI, 0.01 to 0.88; p-trend = 0.043) in univariable models. Combining the cohorts and adjusting for baseline clinical characteristics and SQLE, the OR was 0.30 (95% CI, 0.12 to 0.72; p-trend = 0.009). CYP27A1 was less strongly associated with lethal disease when additionally adjusting for Gleason grade (OR, 0.48; 95% CI, 0.18 to 1.31; p-trend = 0.21).

Conclusion: Low CYP27A1 expression is associated with higher cholesterol synthesis and a higher risk of progression to lethal disease among prostate cancer patients, potentially partly due to its association with higher Gleason grade. We found little evidence that intratumoral CYP27A1 expression is associated with circulating 25(OH)D. Our results highlight the importance of the regulation of cholesterol metabolism in prostate cancer progression.

Citation Format: Nabeela A. Khan, Konrad H. Stopsack, Emma H. Allott, Travis A. Gerke, Edward L. Giovannucci, Lorelei A. Mucci, Philip W. Kantoff. Intratumoral CYP27A1 expression in relation to cholesterol synthesis and vitamin D signaling and its association with lethal prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1450.

TP53 protein levels, RNA-based pathway assessment, and race among invasive breast cancer cases

Mutations in tumor suppressor TP53 have been inconsistently linked to breast cancer risk factors and survival. Immunohistochemistry (IHC) staining, a primary clinical means of TP53 mutation determination, only detects mutations that facilitate protein accumulation (e.g., missense mutations). RNA-based pathway methods capture functional status and may aid in understanding the role of TP53 function in racial disparities of breast cancer. TP53 status was assessed among invasive breast cancer cases from the Carolina Breast Cancer Study (CBCS) (2008–2013) using IHC and an established RNA-based TP53 signature (CBCS and The Cancer Genome Atlas (TCGA)). Frequency of TP53 status (IHC, RNA-based) was estimated in association with tumor characteristics, PAM50 intrinsic subtype, age, and race using relative frequency differences (RFDs) and 95% confidence intervals (95% CI) as the measure of association. Approximately 60% of basal-like tumors were TP53 protein positive (IHC), while nearly 100% were TP53 mutant-like (RNA). Luminal A tumors had low frequency of TP53 positivity (IHC: 7.9%) and mutant-like status (RNA: 1.7%). Mutant-like TP53 (RNA) was strongly associated with age ≤50 years, high tumor grade, advanced stage of disease, large tumor size, and basal-like and HER2 intrinsic subtypes. Black race was strongly associated with TP53 mutant-like status (RNA) (RFD: 24.8%, 95% CI: 20.5, 29.0) even after adjusting for age, grade, stage (RFD: 11.3%; 95% CI: 7.6, 15.0). Associations were attenuated and non-significant when measured by IHC. IHC-based TP53 status is an insensitive measurement of TP53 functional status. RNA-based methods suggest a role for TP53 in tumor prognostic features and racial disparities.

RNA-based assays offer a more sensitive and clinically informative measure of mutations in the tumor suppressor TP53 among women with invasive breast cancer than do immunohistochemistry techniques that can only detect altered proteins. Using tumor samples from more than 1000 women enrolled in the Carolina Breast Cancer Study (CBCS), Melissa Troester from the University of North Carolina at Chapel Hill, USA, and coworkers assessed the functional status of TP53 via both classical immunohistochemistry methods and an RNA-based test of expression levels among 52 TP53-dependent genes. The results of the RNA analysis were strongly associated with younger age-of-onset, higher grade tumors, more advanced stage disease, larger tumor size, aggressive cancer subtypes and race—with more black women harboring TP53 mutant-like tumors than white women. By comparison, these associations were weaker or non-significant when using immunohistochemistry-based tests.

PAM50 and Risk of Recurrence Scores for Interval Breast Cancers

Breast cancers detected after a negative breast screening examination and prior to the next screening are referred to as interval cancers. These cancers generally have poor clinical characteristics compared with screen-detected cancers, but associations between interval cancer and genomic cancer characteristics are not well understood. Mammographically screened women diagnosed with primary invasive breast cancer from 1993 to 2013 (n = 370) were identified by linking the Carolina Breast Cancer Study and the Carolina Mammography Registry. Among women with a registry-identified screening mammogram 0 to 24 months before diagnosis, cancers were classified as screen-detected (N = 165) or interval-detected (N = 205). Using logistic regression, we examined the association of mode of detection with cancer characteristics (clinical, IHC, and genomic), overall, and in analyses stratified on mammographic density and race. Interval cancer was associated with large tumors [>2 cm; OR, 2.3; 95% confidence interval (CI), 1.5-3.7], positive nodal status (OR, 1.8; 95% CI, 1.1-2.8), and triple-negative subtype (OR, 2.5; 95% CI, 1.1-5.5). Interval cancers were more likely to have non-Luminal A subtype (OR, 2.9; 95% CI, 1.5-5.7), whereas screen-detected cancers tended to be more indolent (96% had low risk of recurrence genomic scores; 71% were PAM50 Luminal A). When stratifying by mammographic density and race, associations between interval detection and poor prognostic features were similar by race and density status. Strong associations between interval cancers and poor-prognosis genomic features (non-Luminal A subtype and high risk of recurrence score) suggest that aggressive tumor biology is an important contributor to interval cancer rates. Cancer Prev Res; 11(6); 327-36. ©2018 AACR.

Serum cholesterol levels and tumor growth in a PTEN-null transgenic mouse model of prostate cancer

Background

Some, but not all, epidemiologic evidence supports a role for cholesterol, the precursor for steroid hormone synthesis, in prostate cancer. Using a PTEN-null transgenic mouse model of prostate cancer, we tested the effect of modifying serum cholesterol levels on prostate tumor development and growth. We hypothesized that serum cholesterol reduction would lower tumor androgens and slow prostate cancer growth.

Methods

PTEN^loxP/loxP-Cre⁺ mice consuming ad libitum high fat, high cholesterol diets (40% fat, 1.25% cholesterol) were randomized after weaning to receive the cholesterol uptake inhibitor, ezetimibe (30 mg/kg/day), or no intervention, and sacrificed at 2, 3 or 4 months of age. Serum cholesterol and testosterone were measured by ELISA and intraprostatic androgens by mass spectrometry. Prostate histology was graded, and proliferation and apoptosis in tumor epithelium and stroma was assessed by Ki67 and TUNEL, respectively.

Results

Ezetimibe-treated mice had lower serum cholesterol at 4 months (p=0.031). Serum cholesterol was positively correlated with prostate weight (p=0.033) and tumor epithelial proliferation (p=0.069), and negatively correlated with tumor epithelial apoptosis (p=0.004). Serum cholesterol was unrelated to body weight (p=0.195). Tumor stromal cell proliferation was reduced in the ezetimibe group (p=0.010). Increased serum cholesterol at 4 months was associated with elevated intraprostatic DHEA, testosterone and androstenedione (p=0.043, p=0.074, p=0.031, respectively). However, cholesterol reduction did not significantly affect adenocarcinoma development at 2, 3 or 4 months of age (0%, 78%, 100% in ezetimibe-treated vs. 0%, 80%, 100% in mice not receiving ezetimibe).

Conclusions

Though serum cholesterol reduction did not significantly affect the rate of adenocarcinoma development in the PTEN-null transgenic mouse model of prostate cancer, it lowered intraprostatic androgens and slowed tumor growth. These findings support a role for serum cholesterol in promoting prostate cancer growth, potentially via enhanced tumor androgen signaling, and may provide new insight into cholesterol-lowering interventions for prostate cancer treatment.

Geographic Differences in Baseline Prostate Inflammation and Relationship with Subsequent Prostate Cancer Risk: Results from the Multinational REDUCE Trial

Background: Prostate cancer incidence rates vary 25-fold worldwide. Differences in PSA screening are largely, but not entirely, responsible. We examined geographic differences in prevalence of histologic prostate inflammation and subsequent prostate cancer risk.Methods: Seven thousand nonHispanic white men were enrolled in the REduction by DUtasteride of prostate Cancer Events (REDUCE) trial from Europe (n = 4,644), North America (n = 1,746), South America (n = 466), and Australia/New Zealand (n = 144). Histologic inflammation in baseline negative prostate biopsies was classified as chronic (lymphocytes/macrophages) or acute (neutrophils). Multivariable logistic regression was used to examine associations between region and prostate inflammation, and between region and prostate cancer risk at 2-year biopsy.Results: Prevalence of prostate inflammation varied across region, with broadly similar patterns for acute and chronic inflammation. Relative to Europe, prevalence of acute inflammation was higher in North America [odds ratio (OR), 1.77; 95% confidence interval (CI), 1.51-2.08] and Australia/New Zealand (OR, 2.07; 95% CI, 1.40-3.06). Men from these regions had lower prostate cancer risk than Europeans at biopsy. Among North Americans, prevalence of acute inflammation was higher in Canada versus the United States (OR, 1.40; 95% CI, 1.07-1.83), but prostate cancer risk did not differ between these regions. Among Europeans, prevalence of acute inflammation was lower in Northern and Eastern (OR, 0.79; 95% CI, 0.65-0.97 and OR 0.62; 95% CI, 0.45-0.87, respectively), relative to Western Europe, and these men had higher prostate cancer risk at biopsy.Conclusions: Prevalence of histologic prostate inflammation varied by region. Geographic differences in prostate inflammation tracked inversely with geographic differences in prostate cancer risk.Impact: Characterization of premalignant prostate biology and the relationship with subsequent prostate cancer risk could inform prostate cancer prevention efforts. Cancer Epidemiol Biomarkers Prev; 27(7); 783-9. ©2018 AACR.

Translating Mechanism-Based Strategies to Break the Obesity-Cancer Link: A Narrative Review

Prevalence of obesity, an established risk factor for many cancers, has increased dramatically over the past 50 years in the United States and across the globe. Relative to normoweight cancer patients, obese cancer patients often have poorer prognoses, resistance to chemotherapies, and are more likely to develop distant metastases. Recent progress on elucidating the mechanisms underlying the obesity-cancer connection suggests that obesity exerts pleomorphic effects on pathways related to tumor development and progression and, thus, there are multiple opportunities for primary prevention and treatment of obesity-related cancers. Obesity-associated alterations, including systemic metabolism, adipose inflammation, growth factor signaling, and angiogenesis, are emerging as primary drivers of obesity-associated cancer development and progression. These obesity-associated host factors interact with the intrinsic molecular characteristics of cancer cells, facilitating several of the hallmarks of cancer. Each is considered in the context of potential preventive and therapeutic strategies to reduce the burden of obesity-related cancers. In addition, this review focuses on emerging mechanisms behind the obesity-cancer link, as well as relevant dietary interventions, including calorie restriction, intermittent fasting, low-fat diet, and ketogenic diet, that are being implemented in preclinical and clinical trials, with the ultimate goal of reducing incidence and progression of obesity-related cancers.

Racial Differences in PAM50 Subtypes in the Carolina Breast Cancer Study

Background

African American breast cancer patients have lower frequency of hormone receptor-positive (HR+)/human epidermal growth factor receptor 2 (HER2)-negative disease and higher subtype-specific mortality. Racial differences in molecular subtype within clinically defined subgroups are not well understood.

Methods

Using data and biospecimens from the population-based Carolina Breast Cancer Study (CBCS) Phase 3 (2008-2013), we classified 980 invasive breast cancers using RNA expression-based PAM50 subtype and recurrence (ROR) score that reflects proliferation and tumor size. Molecular subtypes (Luminal A, Luminal B, HER2-enriched, and Basal-like) and ROR scores (high vs low/medium) were compared by race (blacks vs whites) and age (≤50 years vs > 50 years) using chi-square tests and analysis of variance tests.

Results

Black women of all ages had a statistically significantly lower frequency of Luminal A breast cancer (25.4% and 33.6% in blacks vs 42.8% and 52.1% in whites; younger and older, respectively). All other subtype frequencies were higher in black women (case-only odds ratio [OR] = 3.11, 95% confidence interval [CI] = 2.22 to 4.37, for Basal-like; OR = 1.45, 95% CI = 1.02 to 2.06, for Luminal B; OR = 2.04, 95% CI = 1.33 to 3.13, for HER2-enriched). Among clinically HR+/HER2- cases, Luminal A subtype was less common and ROR scores were statistically significantly higher among black women.

Conclusions

Multigene assays highlight racial disparities in tumor subtype distribution that persist even in clinically defined subgroups. Differences in tumor biology (eg, HER2-enriched status) may be targetable to reduce disparities among clinically ER+/HER2- cases.

Biology and Etiology of Young-Onset Breast Cancers among Premenopausal African American Women: Results from the AMBER Consortium

Background: African American (AA) women have higher incidence of aggressive, young-onset (<40 years) breast cancers. Young- and older-onset disease may have distinct tumor biologies and etiologies; however, studies investigating age differences among AA women have been rare and generally underpowered.Methods: We examined tumor characteristics and breast cancer risk factors associated with premenopausal young (<40) vs. older (≥40) AA women's breast cancer in the African American Breast Cancer Epidemiology and Risk Consortium (2,008 cases and 5,144 controls). Unconditional logistic regression models assessed heterogeneity of tumor biology and risk factor associations by age, overall, and by estrogen receptor status.Results: Premenopausal AA women <40 years had higher frequency of poorer-prognosis tumor characteristics compared with older women, including negative estrogen and progesterone receptor status, triple-negative subtype, higher grade, higher stage, and larger tumors. Adiposity (i.e., waist-to-hip ratio) and family history of breast cancer were more strongly associated with young-onset disease [case-control OR = 1.46, 95% confidence interval (CI) = 1.04-2.05; OR = 3.10, 95% CI = 2.08-4.63, respectively] compared with older-onset disease (OR = 1.11, 95% CI = 0.91-1.35; OR = 1.57, 95% CI = 1.26-1.94). Breastfeeding showed a slight inverse risk association among young women (OR = 0.70, 95% CI = 0.43-1.16). Oral contraceptive use was associated with increased risk regardless of age. Considering various cutoff points for young age (<40, <45, <50), age-related heterogeneity was greatest when <40 was used.Conclusions: Among premenopausal AA women, diagnosis before age 40 is associated with more aggressive breast tumor biology and some etiologic differences.Impact: Modifiable risk factors including breastfeeding, adiposity, and oral contraceptive use may be important targets for mitigating harms of young-onset breast cancer. Cancer Epidemiol Biomarkers Prev; 26(12); 1722-9. ©2017 AACR.

Abstract 4962: Geographic disparities in prevalence of baseline prostate inflammation and prostate cancer risk: Results from a multinational trial

Introduction: Prostate cancer incidence rates vary 25-fold worldwide. The distribution of lifestyle factors also varies by geographic region and these factors may impact prostate inflammation, which is inversely associated with prostate cancer risk in the REduction by DUtasteride of prostate Cancer Events (REDUCE) trial. Herein, we examined geographic differences in the prevalence of histological prostate inflammation and geographic differences in prostate cancer risk using REDUCE, a multinational trial of men with a negative baseline prostate biopsy.

Methods: We conducted a retrospective analysis of data from 7,213 men with a negative baseline prostate biopsy in REDUCE from Europe (n=4,802), North America (n=1,796), South America (n=467), and Australia/New Zealand (n=148). Histological inflammation was classified as chronic (lymphocytes, macrophages) or acute (neutrophils) by central review of negative baseline prostate biopsies. Logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (95% CI) for associations between geographic region and prostate inflammation, and between geographic region and prostate cancer risk at trial-mandated repeat biopsy, adjusting for potential confounders. To avoid confounding by race, analyses were restricted to white men.

Results: Chronic and acute prostate inflammation was detected in 77% and 15% of men, respectively. Relative to Europeans, North Americans and Australians/New Zealanders were more likely to have acute prostate inflammation in the negative biopsy (OR 1.74; 95% CI 1.48-2.05 and OR 2.04; 95% CI 1.38-3.02, respectively), while South Americans were less likely to have acute inflammation (OR 0.42; 95% CI 0.28-0.61). Among North Americans, Canadians were more likely to have acute prostate inflammation than men from the United States (OR 1.40; 95% CI 1.07-1.83). Among Europeans, the prevalence of acute inflammation was lower in Northern, Southern and Eastern Europe, relative to Western Europe (OR 0.79; 95% CI 0.65-0.97, OR 0.84; 95% CI 0.66-1.07 and OR 0.62; 95% CI 0.45-0.87, respectively), with similar results for chronic inflammation. Regions with higher prevalence of prostate inflammation had lower prostate cancer risk at 2-year biopsy, including North America (OR 0.87; 95% CI 0.71-1.07) and Australia/New Zealand (OR 0.48; 95% CI 0.24-0.95), relative to Europe. Conversely, regions with lower prevalence of prostate inflammation had higher prostate cancer risk at 2-year biopsy, including Northern and Eastern Europe (OR 1.30; 95% CI 1.05-1.62 and OR 1.74; 95% CI 1.29-2.35, respectively), relative to Western Europe.

Conclusions: Geographic disparities in the prevalence of prostate inflammation is a potential biologic mechanism contributing to global differences in prostate cancer incidence rates.

Citation Format: Emma H. Allott, Sarah Markt, Lauren E. Howard, Adriana C. Vidal, Daniel M. Moreira, Ramiro Castro-Santamaria, Gerald L. Andriole, Lorelei A. Mucci, Stephen J. Freedland. Geographic disparities in prevalence of baseline prostate inflammation and prostate cancer risk: Results from a multinational trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4962. doi:10.1158/1538-7445.AM2017-4962

Statin Use, Serum Lipids, and Prostate Inflammation in Men with a Negative Prostate Biopsy: Results from the REDUCE Trial

Statin use is associated with lower advanced prostate cancer risk. In addition to cholesterol lowering, statins have systemic anti-inflammatory properties. However, their effect on histologic prostate inflammation is not well understood, particularly among men at increased prostate cancer risk but with a negative prostate biopsy. We examined associations between serum lipid levels, statin use, and histologic prostate inflammation using data from 6,655 men with a negative baseline prostate biopsy in the REduction by DUtasteride of prostate Cancer Events (REDUCE) trial. Statin use and lipid levels [total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglycerides] were assessed at baseline. Inflammation was assessed by central review. Logistic regression was used to examine the effects of lipids and statin use on presence and extent of chronic and acute prostate inflammation [none, moderate (<20%), severe (≥20% biopsy cores)]. Chronic and acute inflammation affected 77% and 15% of men, respectively. Men with high HDL (≥60 vs. <40 mg/dL) had reduced presence of acute inflammation [OR, 0.79; 95% confidence interval (CI), 0.63-0.99] and were less likely to have severe acute inflammation (OR, 0.66; 95% CI, 0.45-0.97), but there were no other associations between lipids and inflammation. Statin users had reduced presence of chronic inflammation (OR, 0.81; 95% CI, 0.69-0.95) and were less likely to have severe chronic (OR, 0.80; 95% CI, 0.68-0.95) and severe acute inflammation (OR, 0.73; 95% CI, 0.53-1.00), relative to non-users. Given the possible role for inflammation in prostate cancer, the inverse association between statins and prostate inflammation suggests a mechanism linking statins with lower advanced prostate cancer risk. Cancer Prev Res; 10(6); 319-26. ©2017 AACR.

Impact of carbohydrate restriction in the context of obesity on prostate tumor growth in the Hi-Myc transgenic mouse model

Introduction

Previously, we showed that carbohydrate restriction with calorie restriction slowed tumor growth in xenograft mouse prostate cancer models. Herein, we examined the impact of carbohydrate restriction without calorie restriction on tumor development within the context of diet-induced obesity in the Hi-Myc transgenic mouse model of prostate cancer.

Methods

Mice were randomized at 5 weeks of age to ad libitum Western diet (WD; 40% fat, 42% carbohydrate; n=39) or ad libitum no carbohydrate ketogenic diet (NCKD; 82% fat, 1% carbohydrate; n=44). At age 3 or 6 months, mice were sacrificed, prostates weighed and prostate histology, proliferation, apoptosis, and macrophage infiltration evaluated by H&E, Ki67, TUNEL and F4/80 staining, respectively. Body composition was assessed by DEXA, serum cytokines measured using multiplex, and Akt/mTOR signaling assessed by Western.

Results

Caloric intake was higher in the NCKD group, resulting in elevated body weights at 6 months of age, relative to the WD group (45g vs. 38g; p=0.008). Despite elevated body weights, serum MCP-1 and IL-1α levels were lower in NCKD versus WD mice (p=0.046 and p=0.118, respectively), and macrophage infiltration was reduced in prostates of NCKD versus WD mice (p=0.028). Relative Akt phosphorylation and phospho-S6 ribosomal protein levels were reduced in prostates of NCKD versus WD mice. However, while mice randomized to NCKD had smaller prostates after adjustment for body weight at 3 and 6 months (p=0.004 and p=0.002, respectively), NCKD mice had higher rates of adenocarcinoma at 6 months compared to WD mice (100% vs. 80%, p=0.04).

Conclusions

Despite higher caloric intake and elevated body weights, carbohydrate restriction lowered serum MCP-1 levels, reduced prostate macrophage infiltration, reduced prostate weight, but failed to slow adenocarcinoma development. Together, these data suggest that although carbohydrate restriction within the context of obesity may reduce obesity-associated systemic inflammation, it is not sufficient to counteract obesity-associated tumor growth.

Abstract PD8-01: Race and age differences in PAM50 biomarker status in the Carolina breast cancer study

Background: African American breast cancer patients have lower relative frequency of hormone receptor (HR)-positive/HER2-negative disease and higher subtype-specific mortality. However, few population-based studies have RNA-based subtyping data, and racial differences in the biology of HR-positive/HER2-negative tumors are not well understood.

Methods: Using data and biospecimens from the Carolina Breast Cancer Study (CBCS) Phase 3 (2008-2013), we classified approximately 1,000 invasive breast cancers according to PAM50 subtype and two risk of recurrence scores (ROR-P and ROR-PT). Relative frequency of Luminal A, Luminal B, Her2-enriched, and Basal-like subtypes and ROR scores (low/medium/high) were compared by race (blacks vs. whites) and age (≤50 years vs. &gt;50 years), overall and among HR-positive/HER2-negative cases.

Results: Black women of all ages had significantly higher relative frequency of Basal-like breast cancer (36 and 31% in blacks vs. 18 and 15% in whites; younger and older, respectively) and lower frequency of Luminal A breast cancer (26 and 34% in blacks vs. 43 and 52% in whites; younger and older, respectively). Frequency of Luminal B and HER2-enriched breast cancer did not vary by race or age. Among clinically HR-positive, HER2-negative cases, Luminal A subtype comprised only half of the cases among black women, and was significantly less common than among white women (51% vs 60% in whites, p&lt;0.05). Black women with HR-positive/HER2-negative disease also had significantly higher ROR scores (ROR-P medium or high 82% vs. 66% in whites, p=0.01; ROR-PT medium or high 85% vs. 69% in whites, p&lt;0.01).

Conclusions: Multi-gene assays highlight disparities in frequency of aggressive, poorer prognosis tumor subtypes and implicate differences in tumor biology as an important contributor to mortality disparities among HR-positive/HER2-negative patients.

Citation Format: Troester MA, Sun X, Allott EH, Kit C-K, Thorne L, Mathews M, Cohen SM, Geradts J, Kirk E, Li Y, Hu Z, Robinson W, Hoadley KA, Reeder-Hayes K, Earp S, Olshan AF, Carey LA, Perou CM. Race and age differences in PAM50 biomarker status in the Carolina breast cancer study [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr PD8-01.

Abstract 1760: Saturated fat intake and prostate cancer aggressiveness: Results from the population-based North Carolina-Louisiana prostate cancer project

Introduction: Epidemiologic data support a positive association between hypercholesterolemia and aggressive prostate cancer, and an inverse association between statin use and aggressive prostate cancer. Saturated fat intake is an important dietary determinant of serum cholesterol levels. However, epidemiologic evidence supporting a role for saturated fat in prostate cancer aggressiveness is mixed. We hypothesized that high saturated fat intake would be associated with increased prostate cancer aggressiveness, and that this association would be modified by statin use.

Methods: Of 1,854 prostate cancer cases in the North Carolina-Louisiana Prostate Cancer Project (PCaP), 321 (17%) were classified as high aggressive based on clinical criteria. Saturated fat intake was adjusted for total fat intake using the residual method, and categorized into tertiles based on the distribution among all research subjects. Using low and intermediate aggressive cases as the reference group, logistic regression was used to examine the association between tertiles of saturated fat intake and prostate cancer aggressiveness, overall and stratified by race and by statin use. In addition to demographic and screening variables, energy-adjusted total fat intake and energy intake were included as covariates in our models. In secondary analysis, we examined associations for total fat, monounsaturated and polyunsaturated fatty acids (MUFA and PUFA, respectively), trans fat, and cholesterol intake.

Results: High saturated fat intake was associated with an elevated odds ratio (OR) for aggressive prostate cancer (ORupper tertile (T3) vs. lower (T1) 1.44; 95% CI 1.06-1.96; p-trend = 0.020). The magnitude of this association was weaker in statin users (ORT3 vs. T1 1.10; 95% CI 0.63-1.91; p-trend = 0.790) compared to men not using statins (ORT3 vs. T1 1.63; 95% CI 1.11-2.37; p-trend = 0.015). There was a suggestion of a positive association between high cholesterol intake and aggressive prostate cancer among all men (ORT3 vs. T1 1.28; 95% CI 0.94-1.75; p-trend = 0.074), and this association was more pronounced in European Americans (ORT3 vs. T1 1.82; 95% CI 1.15-2.88; p-trend = 0.012). Elevated PUFA intake was inversely associated with prostate cancer aggressiveness (ORT3 vs. T1 0.66; 95% CI 0.48-0.90; p-trend = 0.009), with similar effect estimates in both races. There were no associations between trans fat or MUFA and prostate cancer aggressiveness.

Conclusions: Elevated intake of saturated fat was positively associated, while high intake of PUFA was inversely associated, with aggressive prostate cancer. Weaker associations between saturated fat and prostate cancer aggressiveness in statin users suggest that the impact of saturated fat on serum cholesterol levels may be one potential mechanism by which saturated fat impacts prostate cancer aggressiveness.

Citation Format: Emma H. Allott, Lenore Arab, L. Joseph Su, Laura Farnan, Elizabeth T.H. Fontham, James L. Mohler, Jeannette T. Bensen, Susan E. Steck. Saturated fat intake and prostate cancer aggressiveness: Results from the population-based North Carolina-Louisiana prostate cancer project. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1760.

Intratumoral heterogeneity as a source of discordance in breast cancer biomarker classification

BACKGROUND

Spatial heterogeneity in biomarker expression may impact breast cancer classification. The aims of this study were to estimate the frequency of spatial heterogeneity in biomarker expression within tumors, to identify technical and biological factors contributing to spatial heterogeneity, and to examine the impact of discordant biomarker status within tumors on clinical record agreement.

METHODS

Tissue microarrays (TMAs) were constructed using two to four cores (1.0 mm) for each of 1085 invasive breast cancers from the Carolina Breast Cancer Study, which is part of the AMBER Consortium. Immunohistochemical staining for estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) was quantified using automated digital imaging analysis. The biomarker status for each core and for each case was assigned using clinical thresholds. Cases with core-to-core biomarker discordance were manually reviewed to distinguish intratumoral biomarker heterogeneity from misclassification of biomarker status by the automated algorithm. The impact of core-to-core biomarker discordance on case-level agreement between TMAs and the clinical record was evaluated.

RESULTS

On the basis of automated analysis, discordant biomarker status between TMA cores occurred in 9 %, 16 %, and 18 % of cases for ER, PR, and HER2, respectively. Misclassification of benign epithelium and/or ductal carcinoma in situ as invasive carcinoma by the automated algorithm was implicated in discordance among cores. However, manual review of discordant cases confirmed spatial heterogeneity as a source of discordant biomarker status between cores in 2 %, 7 %, and 8 % of cases for ER, PR, and HER2, respectively. Overall, agreement between TMA and clinical record was high for ER (94 %), PR (89 %), and HER2 (88 %), but it was reduced in cases with core-to-core discordance (agreement 70 % for ER, 61 % for PR, and 57 % for HER2).

CONCLUSIONS

Intratumoral biomarker heterogeneity may impact breast cancer classification accuracy, with implications for clinical management. Both manually confirmed biomarker heterogeneity and misclassification of biomarker status by automated image analysis contribute to discordant biomarker status between TMA cores. Given that manually confirmed heterogeneity is uncommon (<10 % of cases), large studies are needed to study the impact of heterogeneous biomarker expression on breast cancer classification and outcomes.

Abstract P1-07-04: Etiologic heterogeneity in breast cancer across quantitative levels of estrogen receptor expression

Introduction: The clinical classification of breast cancer into at least four intrinsic subtypes has advanced targeted therapy and improved prognosis. However, for etiological classification, it has been proposed that breast cancer is comprised of just two main subtypes: basal-like and non-basal-like. Evidence for these two etiologic subtypes emerges strongly from bimodal age frequency distributions at diagnosis. In the absence of RNA-based intrinsic subtyping, estrogen receptor (ER) expression is a useful surrogate for these two distinct etiologic classes. Using data from the population-based Carolina Breast Cancer Study (CBCS), we examined evidence for a two-component (ER-positive vs. ER-negative) mixture model for breast cancer biologic/etiologic heterogeneity.

Methods: Automated digital scoring of ER expression was performed on immunohistochemistry-stained tissue microarrays comprising 1,920 invasive breast cancer cases from CBCS. Clinical classification of ER status has changed over time as new data have emerged regarding optimal treatment-relevant thresholds, but optimal etiologic thresholds have not been established. Therefore, we considered ER status as a quantitative, categorical variable with cut points of &lt;1% (ER-negative) vs. ≥1% (ER-positive), with ER-positive cases further categorized as highly positive (≥80-100%), intermediate (≥40-&lt;80%), low (≥10-&lt;40%) or borderline (≥1-&lt;10%). Smoothed age frequency distributions at diagnosis (i.e., density plots) were constructed and logistic regression adjusted for age and race was conducted to assess associations between patient and tumor characteristics and level of ER positivity.

Results: As expected for etiologically-distinct entities, ER-negative and highly ER-positive tumors showed predominantly unimodal early-onset and late-onset age distributions at diagnosis with peak frequencies near ages 50 and 70 years, respectively. However, tumors with low and intermediate positivity showed bimodal patterns, consistent with a mixture of two main subtypes. Consistent with these age distribution patterns, young age (&lt;40 years) at diagnosis was associated with an elevated odds ratio (OR) for low positive (OR 1.8; 95% CI 1.1-2.9), borderline (OR 1.9; 95% CI 1.1-3.3) and ER-negative disease (OR 2.2; 95% CI 1.5-3.2). Relative to highly ER-positive tumors, low ER-positive tumors were more likely to be node-positive (OR 1.4; 95% CI 1.0-1.9), higher grade (combined grade III; OR 1.9; 95% CI 1.3-2.9), and were more likely to harbor a p53 mutation (OR 2.0; 95% CI 1.2-3.5).

Conclusions: While etiologic differences between dichotomized ER-negative and ER-positive breast cancer categories have been well described in many epidemiologic studies, differences in breast cancer etiology across quantitative levels of ER expression have not been so well-characterized. In this study, we report that ER-positive tumors with low positivity share etiologic features of ER-negative tumors, including young age at diagnosis and aggressive tumor characteristics. These data provide additional support for a two-component breast cancer mixture model, with quantitative level of ER positivity reflecting the relative distributions of ER-positive and ER-negative tumor populations.

Citation Format: Allott EH, Tse C-K, Carey L, Anderson WF, Olshan AF, Troester MA. Etiologic heterogeneity in breast cancer across quantitative levels of estrogen receptor expression. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-07-04.

Racial Differences in the Association Between Preoperative Serum Cholesterol and Prostate Cancer Recurrence: Results from the SEARCH Database

BACKGROUND

Black men are disproportionately affected by both cardiovascular disease and prostate cancer. Epidemiologic evidence linking dyslipidemia, an established cardiovascular risk factor, and prostate cancer progression is mixed. As existing studies were conducted in predominantly non-black populations, research on black men is lacking.

METHODS

We identified 628 black and 1,020 non-black men who underwent radical prostatectomy and never used statins before surgery in the Shared Equal Access Regional Cancer Hospital (SEARCH) database. Median follow-up was 2.9 years. The impact of preoperative hypercholesterolemia on risk of biochemical recurrence was examined using multivariable, race-stratified proportional hazards. In secondary analysis, we examined associations with low-density lipoprotein (LDL), high-density lipoprotein (HDL), and triglycerides, overall and among men with dyslipidemia.

RESULTS

High cholesterol was associated with increased risk of recurrence in black [HR(per10 mg/dL) 1.06; 95% confidence interval (CI), 1.02-1.11] but not non-black men (HR(per10 mg/dL) 0.99; 95% CI, 0.95-1.03; P(interaction) = 0.011). Elevated triglycerides were associated with increased risk in both black and non-black men (HR(per10 mg/dL) 1.02; 95% CI, 1.00-1.03 and 1.02; 95% CI, 1.00-1.02, respectively; P(interaction) = 0.458). There were no significant associations between LDL or HDL and recurrence risk in either race. Associations with cholesterol, LDL, and triglycerides were similar among men with dyslipidemia, but low HDL was associated with increased risk of recurrence in black, but not non-black men with dyslipidemia (P(interaction) = 0.047).

CONCLUSION

Elevated cholesterol was a risk factor for recurrence in black but not non-black men, whereas high triglycerides were associated with increased risk regardless of race.

IMPACT

Significantly contrasting associations by race may provide insight into prostate cancer racial disparities.

Performance of Three-Biomarker Immunohistochemistry for Intrinsic Breast Cancer Subtyping in the AMBER Consortium

BACKGROUND

Classification of breast cancer into intrinsic subtypes has clinical and epidemiologic importance. To examine accuracy of IHC-based methods for identifying intrinsic subtypes, a three-biomarker IHC panel was compared with the clinical record and RNA-based intrinsic (PAM50) subtypes.

METHODS

Automated scoring of estrogen receptor (ER), progesterone receptor (PR), and HER2 was performed on IHC-stained tissue microarrays comprising 1,920 cases from the African American Breast Cancer Epidemiology and Risk (AMBER) consortium. Multiple cores (1-6/case) were collapsed to classify cases, and automated scoring was compared with the clinical record and to RNA-based subtyping.

RESULTS

Automated analysis of the three-biomarker IHC panel produced high agreement with the clinical record (93% for ER and HER2, and 88% for PR). Cases with low tumor cellularity and smaller core size had reduced agreement with the clinical record. IHC-based definitions had high agreement with the clinical record regardless of hormone receptor positivity threshold (1% vs. 10%), but a 10% threshold produced highest agreement with RNA-based intrinsic subtypes. Using a 10% threshold, IHC-based definitions identified the basal-like intrinsic subtype with high sensitivity (86%), although sensitivity was lower for luminal A, luminal B, and HER2-enriched subtypes (76%, 40%, and 37%, respectively).

CONCLUSION

Three-biomarker IHC-based subtyping has reasonable accuracy for distinguishing basal-like from nonbasal-like, although additional biomarkers are required for accurate classification of luminal A, luminal B, and HER2-enriched cancers.

IMPACT

Epidemiologic studies relying on three-biomarker IHC status for subtype classification should use caution when distinguishing luminal A from luminal B and when interpreting findings for HER2-enriched cancers.

Is PSA related to serum cholesterol and does the relationship differ between black and white men?

BACKGROUND

Previously, in prostate cancer-free men, we found that statin initiation resulted in a 4.1% decline in PSA. This decline in PSA was proportional to the decline in cholesterol, suggesting a link between cholesterol and PSA levels. Whether these associations vary by race has not been explored and therefore we examined the association between pre-statin serum cholesterol and PSA in black and white prostate cancer-free men.

METHODS

We conducted a retrospective, cross-sectional analysis of 1,163 men (709 white and 454 black) without prostate cancer who initiated a statin between 1994 and 2006. Linear regression was used to test the association between pre-statin serum cholesterol and PSA levels, adjusting for potential confounders and stratifying by race.

RESULTS

Black men were younger, had higher low-density lipoprotein (LDL) and high-density lipoprotein (HDL) levels (both P < 0.05) and a trend toward higher total cholesterol (P = 0.063). There was no difference in PSA or year of statin prescription by race (P = 0.900 and P = 0.217, respectively). On multivariable analysis, we found a positive correlation between serum PSA and total cholesterol (P = 0.005) and LDL (P = 0.003) in white men, but no association among black men. HDL was not significantly related to PSA levels in black or white men (both P > 0.5).

CONCLUSIONS

Among prostate cancer-free men about to begin a statin, pre-statin total cholesterol and LDL were correlated with PSA levels in white, but not black men. If confirmed in future studies, these findings suggest that serum cholesterol may be related to prostate biology, and that this effect may vary by race.

Obesity and cancer: mechanistic insights from transdisciplinary studies

Obesity is associated with a range of health outcomes that are of clinical and public health significance, including cancer. Herein, we summarize epidemiologic and preclinical evidence for an association between obesity and increased risk of breast and prostate cancer incidence and mortality. Moreover, we describe data from observational studies of weight change in humans and from calorie-restriction studies in mouse models that support a potential role for weight loss in counteracting tumor-promoting properties of obesity in breast and prostate cancers. Given that weight loss is challenging to achieve and maintain, we also consider evidence linking treatments for obesity-associated co-morbidities, including metformin, statins and non-steroidal anti-inflammatory drugs, with reduced breast and prostate cancer incidence and mortality. Finally, we highlight several challenges that should be considered when conducting epidemiologic and preclinical research in the area of obesity and cancer, including the measurement of obesity in population-based studies, the timing of obesity and weight change in relation to tumor latency and cancer diagnosis, and the heterogeneous nature of obesity and its associated co-morbidities. Given that obesity is a complex trait, comprised of behavioral, epidemiologic and molecular/metabolic factors, we argue that a transdisciplinary approach is the key to understanding the mechanisms linking obesity and cancer. As such, this review highlights the critical need to integrate evidence from both epidemiologic and preclinical studies to gain insight into both biologic and non-biologic mechanisms contributing to the obesity-cancer link.

Increased biodiversity in the environment improves the humoral response of rats

Previous studies have compared the immune systems of wild and of laboratory rodents in an effort to determine how laboratory rodents differ from their naturally occurring relatives. This comparison serves as an indicator of what sorts of changes might exist between modern humans living in Western culture compared to our hunter-gatherer ancestors. However, immunological experiments on wild-caught animals are difficult and potentially confounded by increased levels of stress in the captive animals. In this study, the humoral immune responses of laboratory rats in a traditional laboratory environment and in an environment with enriched biodiversity were examined following immunization with a panel of antigens. Biodiversity enrichment included colonization of the laboratory animals with helminths and co-housing the laboratory animals with wild-caught rats. Increased biodiversity did not apparently affect the IgE response to peanut antigens following immunization with those antigens. However, animals housed in the enriched biodiversity setting demonstrated an increased mean humoral response to T-independent and T-dependent antigens and increased levels of “natural” antibodies directed at a xenogeneic protein and at an autologous tissue extract that were not used as immunogens.

Carbohydrate intake, glycemic index and prostate cancer risk

BACKGROUND

Reported associations between dietary carbohydrate and prostate cancer (PC) risk are poorly characterized by race.

METHODS

We analyzed the association between carbohydrate intake, glycemic index (GI), and PC risk in a study of white (N = 262) and black (N = 168) veterans at the Durham VA Hospital. Cases were 156 men with biopsy-confirmed PC and controls (N = 274) had a PSA test but were not recommended for biopsy. Diet was assessed before biopsy with a self-administered food frequency questionnaire. Logistic regression models were used to estimate PC risk.

RESULTS

In multivariable analyzes, higher carbohydrate intake, measured as percent of energy from carbohydrates, was associated with reduced PC risk (3rd vs. 1st tertile, OR = 0.41, 95% CI 0.21-0.81, P = 0.010), though this only reached significance in white men (p-trend = 0.029). GI was unrelated to PC risk among all men, but suggestively linked with reduced PC risk in white men (p-trend = 0.066) and increased PC risk in black men (p-trend = 0.172), however, the associations were not significant. Fiber intake was not associated with PC risk (all p-trends > 0.55). Higher carbohydrate intake was associated with reduced risk of high-grade (p-trend = 0.016), but not low-grade PC (p-trend = 0.593).

CONCLUSION

Higher carbohydrate intake may be associated with reduced risk of overall and high-grade PC. Future larger studies are needed to confirm these findings.

Serum lipid profile and risk of prostate cancer recurrence: Results from the SEARCH database

BACKGROUND

Evidence for an association between total cholesterol, low- and high-density lipoproteins (LDL and HDL, respectively), triglycerides, and prostate cancer is conflicting. Given that prostate cancer and dyslipidemia affect large proportions of Western society, understanding these associations has public health importance.

METHODS

We conducted a retrospective cohort analysis of 843 radical prostatectomy (RP) patients who never used statins before surgery within the Shared Equal Access Regional Cancer Hospital (SEARCH) database. Multivariable Cox proportional hazards analysis was used to investigate the association between cholesterol, LDL, HDL, and triglycerides and biochemical recurrence risk. In secondary analysis, we explored these associations in patients with dyslipidemia, defined using National Cholesterol Education Program guidelines.

RESULTS

Elevated serum triglycerides were associated with increased risk of prostate cancer recurrence [HRper 10 mg/dl, 1.03; 95% confidence interval (CI), 1.01-1.05] but associations between total cholesterol, LDL and HDL, and recurrence risk were null. However, among men with dyslipidemia, each 10 mg/dl increase in cholesterol and HDL was associated with 9% increased recurrence risk (HR, 1.09; 95% CI, 1.01-1.17) and 39% reduced recurrence risk (HR, 0.61; 95% CI, 0.41-0.91), respectively.

CONCLUSIONS

Elevated serum triglycerides were associated with increased risk of prostate cancer recurrence. Cholesterol, LDL, or HDL were not associated with recurrence risk among all men. However, among men with dyslipidemia, elevated cholesterol and HDL levels were associated with increased and decreased risk of recurrence, respectively.

IMPACT

These findings, coupled with evidence that statin use is associated with reduced recurrence risk, suggest that lipid levels should be explored as a modifiable risk factor for prostate cancer recurrence.

Abstract 1265: Carbohydrate intake, glycemic index and prostate cancer risk

Background: Reported associations between dietary carbohydrate and prostate cancer (PC) risk are inconsistent and poorly characterized by race. We examined the associations between dietary carbohydrate intake, glycemic index (GI), and PC risk, and whether these associations differed by race.

Methods: We analyzed data from an ongoing case-control study of white (N=262) and black (N=168) veterans at the Durham VA Hospital. Cases were 156 men with biopsy-confirmed PC. Controls were men who had undergone PSA testing but were not recommended for further evaluation. Demographic and lifestyle risk data were collected using self-administered questionnaires prior to diagnosis. Diet information was obtained using the Harvard food frequency questionnaire. Logistic regression models estimated PC risk and results were adjusted for age, race, body mass index BMI and caloric intake.

Results: Among controls, median carbohydrate intake was 224 gms/day, which amounted to 49% (IQR 43-55%) of calories from carbohydrates. Higher total carbohydrate intake was associated with reduced PC risk (3rd tertile vs. 1st tertile, OR=0.29, 95%CI 0.11-0.72, p-trend=0.007). Though associations were similar in black and white men, this only reached significance in black men (p-trend=0.007). When carbohydrate intake was measured as percent of energy from carbohydrates, higher intake was associated with reduced PC risk (3rd tertile vs. 1st tertile, OR=0.57, 95%CI 0.34-0.96, p=0.033). Again, results were similar in both races, though this only reached significance in black men (p-trend=0.025). Similarly, higher fiber intake (p-trend=0.047) was associated with lower risk of PC, with results similar in black and white men. On the contrary, GI was unrelated to PC risk among all men with a suggestion that higher GI may be linked with increased PC risk in black men (p-trend=0.06). When stratified by grade, associations for all dietary factors examined were similar for both low- and high-grade disease.

Conclusion: Among men consuming a Western diet, our findings suggest higher carbohydrate intake and thereby lower intake of other macronutrients (i.e. protein and fat) may be associated with reduced risk of overall PC and both low- and high-grade PC. However, when examining the GI of the diet, though there was no overall association, there was a suggestion that high GI foods may increase PC risk in black men. While larger studies are needed to confirm our findings, especially in black men, these data suggest that among men consuming a Western diet, those eating more complex carbohydrates (i.e. fiber, whole grains) but not refined carbohydrates may have lower PC risk.

Citation Format: Adriana C Vidal, Christina C Williams, Emma H Allott, Lauren E Howard, Delores J Grant, Megan McPhail, Katharine N Sourbeer, Paolo Boffetta, Cathrine Hoyo, Stephen J Freedland. Carbohydrate intake, glycemic index and prostate cancer risk. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1265. doi:10.1158/1538-7445.AM2014-1265

Racial differences in adipose tissue distribution and risk of aggressive prostate cancer among men undergoing radiotherapy

BACKGROUND

Although elevated body mass index (BMI) has been associated with increased risk of aggressive prostate cancer, the importance of adipose tissue distribution is not well understood. We examined associations between overall and visceral obesity and aggressive prostate cancer risk. Moreover, given racial differences in adipose tissue distribution, we examined whether race modified these associations.

METHODS

We conducted a cross-sectional analysis of 308 radiotherapy-treated patients with prostate cancer within the Durham VA from 2005 to 2011. Multivariable logistic regression examined the association between BMI categories and tertiles of waist circumference (WC), visceral fat area (VFA), and periprostatic adipose tissue area (PPAT) with high-grade prostate cancer risk (Gleason score ≥7 vs. ≤6). Models stratified by race examined whether these associations differed between black and nonblack men.

RESULTS

Both elevated BMI (Ptrend = 0.054) and WC (Ptrend = 0.040) were associated with increased high-grade prostate cancer risk, with similar results between races, although the association with BMI was not statistically significant. In contrast, elevated VFA was associated with increased aggressive prostate cancer risk in black men (Ptrend = 0.002) but not nonblack men (Ptrend = 0.831), with a significant interaction between race and VFA (Pinteraction = 0.035). Though similar patterns were observed for PPAT, none was statistically significant.

CONCLUSIONS

Among men undergoing radiotherapy for prostate cancer, visceral obesity is associated with increased aggressive prostate cancer risk, particularly among black men. If confirmed in future studies, these results suggest that adipose tissue distribution differences may contribute to prostate cancer racial disparity.

IMPACT

These findings highlight the need to elucidate mechanisms contributing to racial differences in the association between visceral obesity and aggressive prostate cancer.

Postoperative statin use and risk of biochemical recurrence following radical prostatectomy: results from the Shared Equal Access Regional Cancer Hospital (SEARCH) database

OBJECTIVE

To investigate the effect of statin use after radical prostatectomy (RP) on biochemical recurrence (BCR) in patients with prostate cancer who never received statins before RP.

PATIENTS AND METHODS

We conducted a retrospective analysis of 1146 RP patients within the Shared Equal Access Regional Cancer Hospital (SEARCH) database. Multivariable Cox proportional hazards analyses were used to examine differences in risk of BCR between post-RP statin users vs nonusers. To account for varying start dates and duration of statin use during follow-up, post-RP statin use was treated as a time-dependent variable. In a secondary analysis, models were stratified by race to examine the association of post-RP statin use with BCR among black and non-black men.

RESULTS

After adjusting for clinical and pathological characteristics, post-RP statin use was significantly associated with 36% reduced risk of BCR (hazard ratio [HR] 0.64, 95% confidence interval [CI] 0.47-0.87; P = 0.004). Post-RP statin use remained associated with reduced risk of BCR after adjusting for preoperative serum cholesterol levels. In secondary analysis, after stratification by race, this protective association was significant in non-black (HR 0.49, 95% CI 0.32-0.75; P = 0.001) but not black men (HR 0.82, 95% CI 0.53-1.28; P = 0.384).

CONCLUSION

In this retrospective cohort of men undergoing RP, post-RP statin use was significantly associated with reduced risk of BCR. Whether the association between post-RP statin use and BCR differs by race requires further study. Given these findings, coupled with other studies suggesting that statins may reduce risk of advanced prostate cancer, randomised controlled trials are warranted to formally test the hypothesis that statins slow prostate cancer progression.