SEER and Gene Expression Data Analysis Deciphers Racial Disparity Patterns in Prostate Cancer Mortality and the Public Health Implication

Emerging racial disparities among Medicare beneficiaries and Veterans with metastatic castration-sensitive prostate cancer

BACKGROUND

Previous studies have shown that Black men receive worse prostate cancer care than White men. This has not been explored in metastatic castration-sensitive prostate cancer (mCSPC) in the current treatment era.

METHODS

We evaluated treatment intensification (TI) and overall survival (OS) in Medicare (2015-2018) and Veterans Health Administration (VHA; 2015-2019) patients with mCSPC, classifying first-line mCSPC treatment as androgen deprivation therapy (ADT) + novel hormonal therapy; ADT + docetaxel; ADT + first-generation nonsteroidal antiandrogen; or ADT alone.

RESULTS

We analyzed 2226 Black and 16,071 White Medicare, and 1020 Black and 2364 White VHA patients. TI was significantly lower for Black vs White Medicare patients overall (adjusted odds ratio [OR] 0.68; 95% confidence interval [CI] 0.58-0.81) and without Medicaid (adjusted OR 0.70; 95% CI 0.57-0.87). Medicaid patients had less TI irrespective of race. OS was worse for Black vs White Medicare patients overall (adjusted hazard ratio [HR] 1.20; 95% CI 1.09-1.31) and without Medicaid (adjusted HR 1.13; 95% CI 1.01-1.27). OS was worse in Medicaid vs without Medicaid, with no significant OS difference between races. TI was significantly lower for Black vs White VHA patients (adjusted OR 0.75; 95% CI 0.61-0.92), with no significant OS difference between races.

CONCLUSIONS

Guideline-recommended TI was low for all patients with mCSPC, with less TI in Black patients in both Medicare and the VHA. Black race was associated with worse OS in Medicare but not the VHA. Medicaid patients had less TI and worse OS than those without Medicaid, suggesting poverty and race are associated with care and outcomes.

Incorporating Genetic Risk Into Prostate Cancer Care: Implications for Early Detection and Precision Oncology

The availability and cost of germline and somatic genetic testing have dramatically improved over the past two decades, enabling precision medicine approaches in oncology, with significant implications for prostate cancer (PCa) care. Roughly 12% of individuals with advanced disease are carriers of rare pathogenic germline variants that predispose to particularly aggressive and earlier-onset disease. Several of these variants are already established as clinically actionable by modern precision oncology therapeutics, while others may come to aid the selection of active surveillance, definitive local therapies, and systemic therapies. Concurrently, the number of common variants (ie, incorporated into polygenic risk scores) associated with PCa risk has continued to grow, but with several important considerations both at the intersection of race and ancestry and for early detection of aggressive disease. Family history has historically been used as a proxy for this inherited genetic risk of PCa, but recently emerging evidence examining this relation has shifted our understanding of how best to leverage this tool in PCa care. This review seeks to clarify and contextualize the existing and emerging precision oncology paradigms that use inherited genetic risk in PCa care, for both early detection and localized disease management.

Time from biopsy to radical prostatectomy by race in an equal-access healthcare system: Results from the SEARCH cohort

BACKGROUND

We previously showed that within an equal-access health system, race was not associated with the time between prostate cancer (PC) diagnosis and radical prostatectomy (RP). However, in the more recent time-period of the study (2003-2007), Black men had significantly longer times to RP. We sought to revisit the question in a larger study population with more contemporary patients. We hypothesized that time from diagnosis to treatment would not differ by race, even after accounting for active surveillance (AS) and the exclusion of men at very low to low risk of PC progression.

METHODS

We analyzed data from 5885 men undergoing RP from 1988 to 2017 at eight Veterans Affairs Hospitals from SEARCH. Multiple linear regression was used to compare time from biopsy to RP and to examine the risk of delays (>90 and >180 days) between races. In sensitivity analyses we excluded men deemed to have initially chosen AS based on having >365 days from biopsy to RP and men at very low to low PC risk for progression according to National Comprehensive Cancer Network Clinical Practice Guidelines.

RESULTS

At biopsy, Black men (n = 1959) were younger, had lower body mass index, and higher prostate specific antigen levels, (all p < 0.02), compared to White men (n = 3926). Time from biopsy to RP was longer in Black men (mean days: 98 vs. 92; adjusted ratio of mean number of days, 1.07 [95% confidence interval: 1.03-1.11], p < 0.001); however, there were no differences in delays >90 or >180 days after adjusting for confounders (all p ≥ 0.286). Results were similar following the exclusion of men potentially under on AS and at very low and low risk.

CONCLUSIONS

In an equal-access healthcare system, we did not find evidence of clinically relevant differences in time from biopsy to RP in Black versus White men.

Identification of novel biomarkers differentially expressed between African-American and Caucasian-American prostate cancer patients

Prostate cancer (PCa) incidence and mortality rate vary among racial and ethnic groups with the highest occurrence in African American (AA) men who have mortality rates twice that of Caucasians (CA). In this study, we focused on differential expression of proteins in AA prostate cancer compared to CA using Protein Pathway Array Analysis (PPAA), in order to identify protein biomarkers associated with PCa racial disparity. Fresh frozen prostate samples (n=90) obtained from radical prostatectomy specimens with PCa, including 25 AA tumor, 21 AA benign, 23 CA tumor, 21 CA benign samples were analyzed. A total of 286 proteins and phosphoproteins were assessed using PPAA. By PPAA analysis, 33 proteins were found to be significantly differentially expressed in tumor tissue (n=48, including both CA and AA) in comparison to benign tissue (n=42). We further compared protein expression levels between AA and CA tumor groups and found that 3 proteins were differentially expressed (P<0.05 and q<5%). Aurora was found to be significantly increased in AA tumors, while Cyclin D1 and HNF-3a proteins were downregulated in AA tumors. Predicted risk score was significantly different between AA and CA ethnic groups using logistic regression analysis. In conclusion, we identified Aurora, Cyclin D1 and HNF-3a proteins as being differentially expressed between AA and CA in PCa tissue. Our study suggests that these proteins might be involved in different pathways that lead to aggressive PCa behavior in AA patients, potentially serving as biomarkers for the PCa racial disparity.

Deciphering the Increased Prevalence of TP53 Mutations in Metastatic Prostate Cancer

The prevalence of TP53 mutations in advanced prostate cancers (PCa) is 3 to 5 times of the quantity in primary PCa. By an integrative analysis of the Cancer Genome Atlas and Catalogue of Somatic Mutations in Cancer data, we revealed the supporting evidence for 2 complementary hypotheses: H₁ - TP53 abnormalities promote metastasis or therapy-resistance of PCa cells, and H₂—part of TP53 mutations in PCa metastases occur after the diagnosis of original cancers. The plausibility of these hypotheses can explain the increased prevalence of TP53 mutations in PCa metastases. With H₁ and H₂ as the general assumptions, we developed mathematical models to decipher the change of the percentage frequency (prevalence) of TP53 mutations from primary tumors to metastases. The following results were obtained. Compared to TP53-normal patients, TP53-mutated patients had poorer biochemical relapse-free survival, higher Gleason scores, and more advanced t-stages (P < .01). Single-nucleotide variants in metastases more frequently occurred on G bases of the coding sequence than those in primary cancers (P = .03). The profile of TP53 hotspot mutations was significantly different between primary and metastatic PCa as demonstrated in a set of statistical tests (P < .05). By the derived formulae, we estimated that about 40% TP53 mutation records collected from metastases occurred after the diagnosis of the original cancers. Our study provided significant insight into PCa progression. The proposed models can also be applied to decipher the prevalence of mutations on TP53 (or other driver genes) in other cancer types.

Asian Ethnic Subgroup Disparities in Delays of Surgical Treatment for Breast Cancer

Background

As Asian American breast cancer incidence rises, it is necessary to investigate the origins of differential breast cancer outcomes among Asian ethnic subgroups. This study aimed to examine disparities in delays of breast cancer surgery among Asian ethnic subgroups.

Methods

We obtained California Cancer Registry data on female breast cancer diagnoses and treatment from 2012 to 2017. Our main independent variable was patient race and ethnicity, including 6 Asian ethnic subgroups. Dependent variables included time to surgical treatment for breast cancer and receipt of surgical treatment within 30 and 90 days of diagnosis. We conducted multivariable logistic regression to determine the odds of receiving surgery within 30 and 90 days of diagnosis and multivariable Cox proportional hazards regression to determine the risk of prolonged time to surgery.

Results

In our cohort of 93 168 breast cancer patients, Hispanic (odds ratio [OR] = 0.86, 95% confidence interval [CI] = 0.82 to 0.89) and non-Hispanic Black (OR = 0.83, 95% CI = 0.78 to 0.88) patients were statistically significantly less likely than non-Hispanic White patients to receive surgery within 30 days of breast cancer diagnosis, whereas Asian Indian or Pakistani (OR = 1.23, 95% CI = 1.09 to 1.40) and Chinese (OR = 1.30, 95% CI = 1.20 to 1.40) patients were statistically significantly more likely to receive surgery within 30 days of diagnosis.

Conclusions

This large, population-based retrospective cohort study of female breast cancer patients is the first, to our knowledge, to demonstrate that time to surgical treatment is not equal for all Asians. Distinct differences among Asian ethnic subgroups suggest the necessity of further investigating breast cancer treatment patterns to fully understand and target disparities in breast cancer treatment.

In Situ Analysis of N-Linked Glycans as Potential Biomarkers of Clinical Course in Human Prostate Cancer

Prostate cancer is the most common cancer in men worldwide. Despite its prevalence, there is a critical knowledge gap in understanding factors driving disparities in survival among different cohorts of patients with prostate cancer. Identifying molecular features separating disparate populations is an important first step in prostate cancer research that could lead to fundamental hypotheses in prostate biology, predictive biomarker discovery, and personalized therapy. N-linked glycosylation is a cotranslational event during protein folding that modulates a myriad of cellular processes. Recently, aberrant N-linked glycosylation has been reported in prostate cancers. However, the full clinical implications of dysregulated glycosylation in prostate cancer has yet to be explored. Herein, we performed direct on-tissue analysis of N-linked glycans using matrix-assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI) from tissue microarrays of over 100 patient tumors with over 10 years of follow-up metadata. We successfully identified a panel of N-glycans that are unique between benign and prostate tumor tissue. Specifically, high-mannose as well as tri-and tetra-antennary N-glycans were more abundant in tumor tissue and increase proportionally with tumor grade. Further, we expanded our analyses to examine the N-glycan profiles of Black and Appalachian patients and have identified unique glycan signatures that correlate with recurrence in each population. Our study highlights the potential applications of MALDI-MSI for digital pathology and biomarker discovery for prostate cancer. IMPLICATIONS: MALDI-MSI identifies N-glycan perturbations in prostate tumors compared with benign tissue. This method can be utilized to predict prostate cancer recurrence and study prostate cancer disparities.

Comprehensive Analysis of Multiple Cohort Datasets Deciphers the Utility of Germline Single-Nucleotide Polymorphisms in Prostate Cancer Diagnosis

Prostate cancer susceptibility is a polygenic trait. We aimed to examine the controversial diagnostic utility of single-nucleotide polymorphisms (SNP) for prostate cancer. We analyzed two datasets collected from Europeans and one from Africans. These datasets were generated by the genome-wide association studies, that is, CGEMS, BPC3, and MEC-Africans, respectively. About 540,000 SNPs, including 61 risk markers that constitute a panel termed MK-61, were commonly genotyped. For each dataset, we augmented the MK-61 panel to generate an MK-61⁺ one by adding several thousands of SNPs that were moderately associated with prostate cancer occurrence in external dataset(s). We assessed the diagnostic utility of both panels by measuring their predictive strength for prostate cancer occurrence with AUC statistics. We calculated the theoretical AUCs using quantitative genetics model-based formulae and obtained the empirical estimates via 10-fold cross-validation using statistical and machine learning techniques. For the MK-61 panel, the 95% confidence intervals of the theoretical AUCs (AUC-CI.95) were 0.578-0.655, 0.596-0.656, and 0.539-0.596 in the CGEMS, BPC3, and MEC-Africans cohorts, respectively. For the MK-61⁺ panels, the corresponding AUC-CI.95 were 0.617-0.663, 0.527-0.736, and 0.547-0.565. The empirical AUCs largely fell within the theoretical interval. A promising result (AUC = 0.703, FNR = 0.354, FPR = 0.353) was obtained in the BPC3 cohort when the MK-61⁺ panel was used. In the CGEMS cohort, the MK-61⁺ panel complemented PSA in predicting the disease status of PSA ≥ 2.0 ng/mL samples. This study demonstrates that augmented risk SNP panels can enhance prostate cancer prediction for males of European ancestry, especially those with [Formula: see text]ng/mL. PREVENTION RELEVANCE: This study demonstrates that augmented risk SNP panels can enhance prostate cancer prediction for males of European ancestry, especially those with PSA ≥ 2 ng/mL.