Pooled Analysis of Nine Cohorts Reveals Breast Cancer Risk Factors by Tumor Molecular Subtype

A systematic review of determinants of breast cancer risk among women with benign breast disease

Benign breast disease (BBD) is associated with heterogeneous breast cancer risk. Identifying key breast cancer risk factors for this population may inform breast cancer prevention or early detection strategies. We systematically searched literature databases PubMed, Embase, Scopus, Web of Science, and the Cochrane Library to identify studies reporting associations of demographic, lifestyle, reproductive, and radiological factors with risk of breast cancer among women with biopsy-confirmed BBD. 67 studies met eligibility criteria. Variation was observed for study time period, exposure measurement, comparison groups, outcomes, and adjustment for confounders, precluding meta-analysis. The literature suggested positive risk associations for age at biopsy, family history, mammographic breast density, and time since biopsy, and no association for body mass index, alcohol, smoking, age at menarche, and use of hormonal contraceptives. More research is needed to understand risk factor associations among women with BBD, particularly studies that account for heterogeneity within BBD and breast cancer.

Trends in breast cancer among elderly women: Development in estrogen and HER2 subtypes in the last ten years

BACKGROUND

Increasing life expectancy increases breast cancer (BC) rates in elderly, where better health allows for improved tolerance of treatments. We assessed trends in BC incidence of tumor subtypes for women with focus on the elderly.

METHODS

Changes in BC incidence in women by age from 2012 to 2021 were assessed using data from the Nordic countries. We calculated the incidence of BC subtypes by age group using data from the Danish Breast Cancer Group (DBCG) database. We used generalized linear models assuming a Poisson distribution.

RESULTS

In the Nordic countries, 205 305 women were diagnosed with BC between 2012 and 2021. In Denmark, 50 858 BC patients were diagnosed between 2012 and 2022, identified with tumor characteristics. Incidence of BC among women aged 80+ increased significantly across the Nordic Countries, with 1.24 % per year (95 % CI: 0.07 %: 2.41 %). In Denmark, in the 80+ group, the ER+/HER2- subtype had the highest increase, with 1.98 % per year (95 % CI: 1.10 %: 2.87 %).

CONCLUSION

Across the Nordic countries, incidence of BC in women aged 80+ increased. In Denmark, rising incidence of BC is driven by the ER+/HER2- subtype in the 80+ group, which has the best prognosis and gentle treatments. More elderly BC patients will require treatment and follow-up in the future.

Risk factors for breast cancer subtypes by race and ethnicity: a scoping review

BACKGROUND

Breast cancer consists of distinct molecular subtypes. Studies have reported differences in risk factor associations with breast cancer subtypes, especially by tumor estrogen receptor (ER) status, but their consistency across racial and ethnic populations has not been comprehensively evaluated.

METHODS

We conducted a qualitative, scoping literature review using the Preferred Reporting Items for Systematic Reviews and Meta-analysis, extension for Scoping Reviews to investigate consistencies in associations between 18 breast cancer risk factors (reproductive, anthropometric, lifestyle, and medical history) and risk of ER-defined subtypes in women who self-identify as Asian, Black or African American, Hispanic or Latina, or White. We reviewed publications between January 1, 1990 and July 1, 2022. Etiologic heterogeneity evidence (convincing, suggestive, none, or inconclusive) was determined by expert consensus.

RESULTS

Publications per risk factor ranged from 14 (benign breast disease history) to 66 (parity). Publications were most abundant for White women, followed by Asian, Black or African American, and Hispanic or Latina women. Etiologic heterogeneity evidence was strongest for parity, followed by age at first birth, postmenopausal body mass index, oral contraceptive use, and estrogen-only and combined menopausal hormone therapy. Evidence was limited for other risk factors. Findings were consistent across racial and ethnic groups, although the strength of evidence varied.

CONCLUSION

The literature supports etiologic heterogeneity by ER for some established risk factors that are consistent across race and ethnicity groups. However, in non-White populations evidence is limited. Larger, more comparable data in diverse populations are needed to better characterize breast cancer etiologic heterogeneity.

Survival trends of patients with metaplastic breast carcinoma with different hormone receptor statuses: a SEER-based retrospective cohort study

BACKGROUND

Metaplastic breast carcinoma (MpBC) is a rare histological subtype of breast cancer, and its prognosis is relatively poor. The survival trend of MpBC with different hormone receptor statuses has remained unclear over the past two decades.

METHODS

MpBC patient data were collected from the Surveillance, Epidemiology, and End Results database from 2000 to 2019. Patients were divided into two groups according to their hormone receptor status (negative and positive). The survival probabilities were calculated via Kaplan‒Meier curves. Logistic regression analysis was used to obtain odds ratios for treatment and demographic characteristics. Multivariate Cox regression was used to identify prognostic factors.

RESULTS

A total of 3,076 patients were enrolled, and a significant improvement in survival was observed over the last 10 years. For HR-negative MpBC patients, both overall survival and breast cancer-specific survival improved, whereas no survival improvement was observed for HR-positive patients. Compared with those in the time period from 2000 to 2009, the proportion of negative nodes and the likelihood of receiving chemotherapy increased for HR-negative patients from 2010 to 2019. In the HR-negative subgroup, the survival of Whites improved significantly, whereas the survival of Blacks improved in the HR-positive subgroup.

CONCLUSIONS

The survival of HR-negative MpBC patients has improved significantly in the past 20 years, which may be related to early diagnosis, increased adjuvant therapy and medical development, but no trend towards improvement has been observed in HR-positive patients. Racial disparities in different HR statuses also need to be addressed.

Trends in the incidence and survival of women with hormone receptor-positive breast cancer from 1990 to 2019: a large population-based analysis

Hormone receptor-positive breast cancer (BC) is the most prevalent subtype of BC and is generally correlated with a favorable prognosis. This study aimed to determine the incidence and survival trends among women diagnosed with hormone receptor-positive BC between 1990 and 2019. Female patients with hormone receptor-positive BC for calendar years 1990-2019 were obtained from the Surveillance, Epidemiology, and End Results (SEER) database and categorized into six diagnostic groups according to the year of diagnosis. Age-adjusted incidence rates (IRs) were calculated using joinpoint regression. We used the Kaplan-Meier method and multivariate Cox regression analyses to determine the association between diagnostic groups, and overall survival (OS) and BC-specific survival (BCSS). The final analysis included 370,729 women, among whom 37,943 (10.2%), 49,266 (13.3%), 55,652 (15.0%), 64,451 (17.4%), 77,127 (20.8%), and 86,290 (23.3%) were diagnosed between 1990 and 1994, 1995-1999, 2000-2004, 2005-2009, 2010-2014, and 2015-2019, respectively. Within the overall cohort, IRs gradually increased from 70 per 100,000 in 1990 to 113 per 100,000 in 2019 (average annual percent change, 1.59%; 95% CI, 1.18-1.99). Multivariate Cox regression analysis revealed that the survival outcomes gradually improved over nearly three decades among hormone receptor-positive BC patients, with a 0.8% and 1.3% decrease in risk for all-cause and BC-specific mortality each year, respectively. Compared to 1990-1994, hormone receptor-positive BC patients diagnosed in 2015-2019 had a 22% lower risk of all-cause death (hazard ratio [HR], 0.78; 95% CI, 0.76-0.81) and a 27% lower risk of BC-specific death (HR, 0.73; 95% CI, 0.70-0.76). The development of treatment strategies within the past three decades, especially endocrine therapy, may contribute to the continuous improvement of clinical outcomes in patients with hormone receptor-positive BC.

Functions and mechanisms of RNA m6A regulators in breast cancer (Review)

Breast cancer (BC) is a major malignant tumor in females and the incidence rate of BC has increased worldwide in recent years. N6‑methyladenosine (m6A) is a methylation modification that occurs extensively in eukaryotic RNA. The abnormal expression of m6A and related regulatory proteins can activate or inhibit certain signal pathways or oncogenes, thus affecting the proliferation, metastasis and prognosis of BC. Numerous studies have shown that m6A regulator disorder exists in BC, and this disorder can be reversed. Therefore, m6A is predicted as a potential therapeutic target for BC. However, the molecular mechanism of m6A RNA methylation regulating the occurrence and development of BC has not been comprehensively elucidated. In this review article, the functions of various m6A regulators and the specific mechanisms of certain regulators of the progress of BC were summarized. Furthermore, the dual role of RNA methylation in tumor progression was discussed, concluding that RNA methylation can not only lead to tumorigenesis but at times give rise to inhibition of tumor formation. In addition, further comprehensive analysis on mechanisms of m6A regulators in BC is conducive to screening effective potential targets and formulating targeted treatment strategies, which will provide new methods for the prevention and treatment of BC.

Integrative analyses identified gap junction beta-2 as a prognostic biomarker and therapeutic target for breast cancer

Background

Increasing evidence has shown that connexins are involved in the regulation of tumor development, immune escape, and drug resistance. This study investigated the gene expression patterns, prognostic values, and potential mechanisms of connexins in breast cancer.

Methods

We conducted a comprehensive analysis of connexins using public gene and protein expression databases and clinical samples from our institution. Connexin mRNA expressions in breast cancer and matched normal tissues were compared, and multiomics studies were performed.

Results

Gap junction beta-2 mRNA was overexpressed in breast cancers of different pathological types and molecular subtypes, and its high expression was associated with poor prognosis. The tumor membrane of the gap junction beta-2 mutated group was positive, and the corresponding protein was expressed. Somatic mutation and copy number variation of gap junction beta-2 are rare in breast cancer. The gap junction beta-2 transcription level in the p110α subunit of the phosphoinositide 3-kinase mutant subgroup was higher than that in the wild-type subgroup. Gap junction beta-2 was associated with the phosphoinositide 3-kinase-Akt signaling pathway, extracellular matrix-receptor interaction, focal adhesion, and proteoglycans in cancer. Furthermore, gap junction beta-2 overexpression may be associated with phosphoinositide 3-kinase and histone deacetylase inhibitor resistance, and its expression level correlated with infiltrating CD8+ T cells, macrophages, neutrophils, and dendritic cells.

Conclusions

Gap junction beta-2 may be a promising therapeutic target for targeted therapy and immunotherapy and may be used to predict breast cancer prognosis.

Educational level and characteristics of invasive breast cancer: findings from a French prospective cohort

PURPOSE

Breast cancer (BC) characteristics are known to influence patients survival. Social differences have been reported by previous studies for those characteristics but questions persist because of inconsistent conclusions. We aimed to investigate the impact of education on BC stage, grade, and hormone receptor (HR) status, while adjusting for potential confounders including a broad set of health behaviors, anthropometric measures, and reproductive factors.

METHODS

In the French E3N cohort, 5236 women developed a primary invasive BC for which there was available information on stage, grade, and HR status. No multivariate analyses was performed for BC stage based on the lack of association in bivariate analyses. Odds ratios and confidence intervals were estimated using multinomial logistic regression models for BC grade or binomial logistic regression models for HR status of BC.

RESULTS

Women with a lower education were diagnosed with higher grade BC compared to women with a higher education (1.32 [1.12; 1.57]). This association was slightly attenuated after adjustment for covariates independently and more strongly affected in the fully adjusted model (1.20 [0.99; 1.45]). A significant association was observed between lower education and HR- status of BC (1.20 [1.02; 1.42]) attenuated after adjustment for age at first childbirth (1.12 [0.95; 1.33]).

CONCLUSION

In this cohort, education was associated with BC grade and HR status but not stage at diagnosis. The link between education and BC grade was not entirely explained by the different adjustments. A specific mechanism could be at play and deserves further investigations.

Receptor subtype and outcome of breast cancer - Single-center experience from North India

AIMS/OBJECTIVES

In resource-limited settings, data regarding the impact of molecular/receptor subtypes on breast cancer (BC) are sparse. In this single-center retrospective study from north India, we analyze the outcomes of various molecular subtypes of BC.

MATERIALS AND METHODS

Females with biopsy-proven BC who were treated at our State Cancer Institute from 2014-2018 were included. Data regarding clinicopathological parameters and follow-up details were evaluated. For data analysis, cancers were categorized into 4 subtypes: HR+HER2-, HR+HER2+, HR-HER2+, and HR-HER2-.

RESULTS

Among 944 patients included, HR+HER2- (49.1%) and HR+HER2+ (13.1%) were the most and least common subtypes, respectively. The receptor subtype significantly impacted overall survival (OS). HR+HER2- cancers had the best outcomes while HR-HER2- cancers fared worst (3-yr OS of 94.3% and 69.1%, respectively). On subgroup analysis, the molecular subtype continued to significantly impact OS in patients with tumor grades II and III, disease stages II and III, and age groups of <40 and 40-60 years, respectively (HR-HER2- cancers had the lowest cumulative survival in each subgroup). In patients with metastatic BC, all molecular subtypes except HR+HER2- had a dismal prognosis.

CONCLUSIONS

Overall and across various subgroups, patients with triple-negative BC had the poorest outcomes. Ensuring optimal treatment utilization including affordable access to personalized tailored therapy is the need of the hour to improve long-term outcomes in these patients.

Reproductive characteristics, menopausal status, race and ethnicity, and risk of breast cancer subtypes defined by ER, PR and HER2 status: the Breast Cancer Etiology in Minorities study

BACKGROUND

Associations between reproductive factors and risk of breast cancer differ by subtype defined by joint estrogen receptor (ER), progesterone receptor (PR), and HER2 expression status. Racial and ethnic differences in the incidence of breast cancer subtypes suggest etiologic heterogeneity, yet data are limited because most studies have included non-Hispanic White women only.

METHODS

We analyzed harmonized data for 2,794 breast cancer cases and 4,579 controls, of whom 90% self-identified as African American, Asian American or Hispanic. Questionnaire data were pooled from three population-based studies conducted in California and data on tumor characteristics were obtained from the California Cancer Registry. The study sample included 1,530 luminal A (ER-positive and/or PR-positive, HER2-negative), 442 luminal B (ER-positive and/or PR-positive, HER2-positive), 578 triple-negative (TN; ER-negative, PR-negative, HER2-negative), and 244 HER2-enriched (ER-negative, PR-negative, HER2-positive) cases. We used multivariable unconditional logistic regression models to estimate subtype-specific ORs and 95% confidence intervals associated with parity, breast-feeding, and other reproductive characteristics by menopausal status and race and ethnicity.

RESULTS

Subtype-specific associations with reproductive factors revealed some notable differences by menopausal status and race and ethnicity. Specifically, higher parity without breast-feeding was associated with higher risk of luminal A and TN subtypes among premenopausal African American women. In contrast, among Asian American and Hispanic women, regardless of menopausal status, higher parity with a breast-feeding history was associated with lower risk of luminal A subtype. Among premenopausal women only, luminal A subtype was associated with older age at first full-term pregnancy (FTP), longer interval between menarche and first FTP, and shorter interval since last FTP, with similar OR estimates across the three racial and ethnic groups.

CONCLUSIONS

Subtype-specific associations with reproductive factors overall and by menopausal status, and race and ethnicity, showed some differences, underscoring that understanding etiologic heterogeneity in racially and ethnically diverse study samples is essential. Breast-feeding is likely the only reproductive factor that is potentially modifiable. Targeted efforts to promote and facilitate breast-feeding could help mitigate the adverse effects of higher parity among premenopausal African American women.

Follow-up Routines Matter for Adherence to Endocrine Therapy in the Adjuvant Setting of Breast Cancer

Background

Endocrine therapy (ET) adherence leads to increased survival in breast cancer (BC). How follow-up should be done to maximize adherence is not known.

Objectives

To assess adherence to ET, factors favouring adherence to ET and effects on survival in a population-based cohort of BC patients in western Sweden.

Design

This is a retrospective study.

Methods

We included 358 patients operated for oestrogen receptor-positive BC and recommended 5 years of ET, in Region Halland, Sweden, year 2015 to 2016. Demographical, clinical and pathological data and use of ET were retrieved from the electronic medical records. Patients were considered adherent if taking ET for 5 years or during the full extent of the follow-up, until termination of ET due to BC relapse or death and where renewals of prescriptions of ET covered ⩾80% of the ordinated dose. Two follow-up routines were employed, ie, routine A where patients were contacted annually by nurses and a more passive follow-up routine B where patients were only contacted by nurses at 2 years and 5 years following start of ET.

Results

Medication persistence for 4 years and more was good and similar between patients initiating aromatase inhibitor (AI) and tamoxifen (75.7% and 72.0%, respectively, P = .43). More patients initiating AIs changed ET due to side effects compared with patients initiating tamoxifen (24.3% vs 9.9%, respectively, P < .0001). Endocrine therapy adherence was better for follow-up routine B than for follow-up routine A (hazard ratio [HR] = 2.71 [1.44-5.09], P = .0027).

Conclusions

Adherence to ET in BC is high in Western Sweden. Less regular nurse-initiated contacts between BC patients and nursesled surprisingly to a better adherence than a more regular nurse-initiated contact.

Risk factors for breast cancer subtypes by race and ethnicity: A scoping review of the literature

Background

Breast cancer is comprised of distinct molecular subtypes. Studies have reported differences in risk factor associations with breast cancer subtypes, especially by tumor estrogen receptor (ER) status, but their consistency across racial and ethnic populations has not been comprehensively evaluated.

Methods

We conducted a qualitative, scoping literature review using the Preferred Reporting Items for Systematic Reviews and Meta-analysis, extension for Scoping Reviews to investigate consistencies in associations between 18 breast cancer risk factors (reproductive, anthropometric, lifestyle, and medical history) and risk of ER-defined subtypes in women who self-identify as Asian, Black or African American, Hispanic or Latina, or White. We reviewed publications between January 1, 1990 and July 1, 2022. Etiologic heterogeneity evidence (convincing, suggestive, none, or inconclusive) was determined by expert consensus.

Results

Publications per risk factor ranged from 14 (benign breast disease history) to 66 (parity). Publications were most abundant for White women, followed by Asian, Black or African American, and Hispanic or Latina women. Etiologic heterogeneity evidence was strongest for parity, followed by age at first birth, post-menopausal BMI, oral contraceptive use, and estrogen-only and combined menopausal hormone therapy. Evidence was limited for other risk factors. Findings were consistent across racial and ethnic groups, although the strength of evidence varied.

Conclusion

The literature supports etiologic heterogeneity by ER for some established risk factors that are consistent across race and ethnicity groups. However, in non-White populations evidence is limited. Larger, more comparable data in diverse populations is needed to better characterize breast cancer etiologic heterogeneity.

Current treatment landscape of HR+/HER2- advanced breast cancer in the Nordics: a modified Delphi study

BACKGROUND

This Delphi study aimed to assess current perspectives on hormone receptor-positive/human epidermal growth factor receptor 2-negative(HR+/HER2-) advanced breast cancer (aBC) treatment strategies across the Nordics, and to establish where consensus exists across the Nordics on HR+/HER2- aBC treatment.

MATERIAL AND METHODS

A modified, three-round Delphi method was followed. A steering committee was appointed for study coordination, panellist selection, and questionnaire development. The questionnaires covered relevant topics on HR+/HER2- aBC treatment: treatment patterns in different lines of therapy (first [1L], second [2L], and third [3L]), oligometastatic disease, de novo aBC, brain metastases, age as influential factor, visceral crisis, radiotherapy, diagnostics, and clinical guidelines. Both open and closed-ended questions were included. Consensus was defined as at least 70% agreement.

RESULTS

In total, 28 experienced BC oncologists participated in the study from all five Nordic countries. Overall, topics reaching consensus included: preferred treatment approach in 1L and 2L therapy, treatment of oligometastatic disease, visceral crisis, brain metastases, and age-related treatment considerations. No consensus was reached for 3L therapy and local treatment for primary tumour in de novo aBC. Endocrine therapy (ET) combined with a cyclin-dependent kinase (CDK)4/6 inhibitor was the treatment of choice for 1L and 2L therapy. Treatment patterns in clinical practice did not always follow recommendations in current Nordic guidelines, as seen in the case of recently approved treatments.

DISCUSSION

ET in combination with a CDK4/6 inhibitor is the preferred frontline treatment for HR+/HER2- aBC in the Nordics. The observed discrepancy between current guidelines and clinical practice could be due to differences in the reimbursement of novel treatments in the Nordics. Collaborative research efforts are warranted for topics that lack consensus.

Trajectories of body mass index in adulthood and risk of subtypes of postmenopausal breast cancer

BACKGROUND

Body fatness is a dynamic exposure throughout life. To provide more insight into the association between body mass index (BMI) and postmenopausal breast cancer, we aimed to examine the age at onset, duration, intensity, and trajectories of body fatness in adulthood in relation to risk of breast cancer subtypes.

METHODS

Based on self-reported anthropometry in the prospective Norwegian Women and Cancer Study, we calculated the age at onset, duration, and intensity of overweight and obesity using linear mixed-effects models. BMI trajectories in adulthood were modeled using group-based trajectory modeling. We used Cox proportional hazards models to calculate hazard ratios (HRs) with 95% confidence intervals (CIs) for the associations between BMI exposures and breast cancer subtypes in 148,866 postmenopausal women.

RESULTS

A total of 7223 incident invasive postmenopausal breast cancer cases occurred during follow-up. Increased overweight duration and age at the onset of overweight or obesity were associated with luminal A-like breast cancer. Significant heterogeneity was observed in the association between age at overweight and overweight duration and the intrinsic-like subtypes (pheterogeneity 0.03). Compared with women who remained at normal weight throughout adulthood, women with a descending BMI trajectory had a reduced risk of luminal A-like breast cancer (HR 0.54, 95% CI 0.33-0.90), whereas women with ascending BMI trajectories were at increased risk (HR 1.09; 95% CI 1.01-1.17 for "Normal-overweight"; HR 1.20; 95% CI 1.07-1.33 for "Normal-obesity"). Overweight duration and weighted cumulative years of overweight and obesity were inversely associated with luminal B-like breast cancer.

CONCLUSIONS

In this exploratory analysis, decreasing body fatness from obesity in adulthood was inversely associated with overall, hormone receptor-positive and luminal A-like breast cancer in postmenopausal women. This study highlights the potential health benefits of reducing weight in adulthood and the health risks associated with increasing weight throughout adult life. Moreover, our data provide evidence of intrinsic-like tumor heterogeneity with regard to age at onset and duration of overweight.

Revolutionizing treatment for triple-negative breast cancer: Harnessing the power of exosomal miRNAs for targeted therapy

Triple-negative breast cancer (TNBC) represents a challenging and aggressive form of breast cancer associated with limited treatment options and poor prognosis. Although chemotherapy is a primary therapeutic approach, drug resistance often hinders treatment success. However, the expanding knowledge of TNBC subtypes and molecular biology has paved the way for targeted therapies. Notably, exosomes (extracellular vesicles) have emerged as crucial carriers of tumorigenic factors involved in oncogenesis and drug resistance, facilitating cell-to-cell communication and offering potential as self-delivery systems. Among the cargo carried by exosomes, microRNAs (miRNAs) have gained attention due to their ability to mediate epigenetic changes in recipient cells upon transfer. Research has confirmed dysregulation of exosomal miRNAs in breast cancer cells compared to healthy cells, establishing them as promising biomarkers for cancer diagnosis and prognosis. In this comprehensive review, we summarize the latest research findings that underscore the diagnostic and prognostic significance of exosomal miRNAs in TNBC treatment. Furthermore, we explore contemporary therapeutic approaches utilizing these exosomal miRNAs for the benefit of TNBC patients, shedding light on potential breakthroughs in TNBC management.

Association of reproductive risk factors and breast cancer molecular subtypes: a systematic review and meta-analysis

BACKGROUND

Associations between reproductive factors and breast cancer (BC) risk vary by molecular subtype (i.e., luminal A, luminal B, HER2, and triple negative/basal-like [TNBC]). In this systematic review and meta-analysis, we summarized the associations between reproductive factors and BC subtypes.

METHODS

Studies from 2000 to 2021 were included if BC subtype was examined in relation to one of 11 reproductive risk factors: age at menarche, age at menopause, age at first birth, menopausal status, parity, breastfeeding, oral contraceptive (OC) use, hormone replacement therapy (HRT), pregnancy, years since last birth and abortion. For each reproductive risk factor, BC subtype, and study design (case-control/cohort or case-case), random-effects models were used to estimate pooled relative risks and 95% confidence intervals.

RESULTS

A total of 75 studies met the inclusion criteria for systematic review. Among the case-control/cohort studies, later age at menarche and breastfeeding were consistently associated with decreased risk of BC across all subtypes, while later age at menopause, later age of first childbirth, and nulliparity/low parity were associated with increased risk of luminal A, luminal B, and HER2 subtypes. In the case-only analysis, compared to luminal A, postmenopausal status increased the risk of HER2 and TNBC. Associations were less consistent across subtypes for OC and HRT use.

CONCLUSION

Identifying common risk factors across BC subtypes can enhance the tailoring of prevention strategies, and risk stratification models can benefit from subtype specificity. Adding breastfeeding status to current BC risk prediction models can enhance predictive ability, given the consistency of the associations across subtypes.

Changes in Breast Cancer Risk and Risk Factor Profiles among U.S.-Born and Immigrant Asian American Women Residing in the San Francisco Bay Area

BACKGROUND

Breast cancer incidence rates in women of Asian descent have been increasing in the United States and Asia.

METHODS

In a case-control study of Asian American women from the San Francisco Bay Area, we assessed associations with birthplace and migration-related characteristics and compared risk factors between Asian American and non-Hispanic White women by birthplace and birth cohort.

RESULTS

Birthplace and migration-related characteristics were associated with breast cancer risk only among women in the younger birth cohort (1951-1984) that comprised 355 cases diagnosed at age ≤55 years and 276 sister and population controls. Breast cancer risk was marginally increased among foreign-born women [OR = 1.40; 95% confidence interval (CI), 0.97-2.03] and two-fold among foreign-born Chinese women (OR = 2.16; 95% CI, 1.21-3.88). Two-fold increased risks were associated with migration at age ≥40 years and longer U.S. residence (≥30 years or ≥75% of life). The education level was high among both cases and controls. Differences in the prevalence of risk factors by birthplace and birth cohort suggest temporal changes in reproductive and lifestyle-related factors. The prevalence in risk factors was similar between foreign-born and U.S.-born women in the younger birth cohort, and did not fully explain the observed associations with birthplace and other migration characteristics.

CONCLUSIONS

In contrast to studies from earlier decades, younger foreign-born Asian American women had a higher risk of breast cancer than U.S.-born Asian American women.

IMPACT

It is important and urgent to understand what factors drive the increasing burden of breast cancer in women of Asian descent and implement effective prevention programs.

Validation of a breast cancer risk prediction model based on the key risk factors: family history, mammographic density and polygenic risk

PURPOSE

We compared a simple breast cancer risk prediction model, BRISK (which includes mammographic density, polygenic risk and clinical factors), against a similar model with more risk factors (simplified Rosner) and against two commonly used clinical models (Gail and IBIS).

METHODS

Using nested case-control data from the Nurses' Health Study, we compared the models' association, discrimination and calibration. Classification performance was compared between Gail and BRISK for 5-year risks and between IBIS and BRISK for remaining lifetime risk.

RESULTS

The odds ratio per standard deviation was 1.43 (95% CI 1.32, 1.55) for BRISK 5-year risk, 1.07 (95% CI 0.99, 1.14) for Gail 5-year risk, 1.72 (95% CI 1.59, 1.87) for simplified Rosner 10-year risk, 1.51 (95% CI 1.41, 1.62) for BRISK remaining lifetime risk and 1.26 (95% CI 1.16, 1.36) for IBIS remaining lifetime risk. The area under the receiver operating characteristic curve (AUC) was improved for BRISK over Gail for 5-year risk (AUC = 0.636 versus 0.511, P < 0.0001) and for BRISK over IBIS for remaining lifetime risk (AUC = 0.647 versus 0.571, P < 0.0001). BRISK was well calibrated for the estimation of both 5-year risk (expected/observed [E/O] = 1.03; 95% CI 0.73, 1.46) and remaining lifetime risk (E/O = 1.01; 95% CI 0.86, 1.17). The Gail 5-year risk (E/O = 0.85; 95% CI 0.58, 1.24) and IBIS remaining lifetime risk (E/O = 0.73; 95% CI 0.60, 0.87) were not well calibrated, with both under-estimating risk. BRISK improves classification of risk compared to Gail 5-year risk (NRI = 0.31; standard error [SE] = 0.031) and IBIS remaining lifetime risk (NRI = 0.287; SE = 0.035).

CONCLUSION

BRISK performs better than two commonly used clinical risk models and no worse compared to a similar model with more risk factors.

Neighborhood factors and triple negative breast cancer: The role of cumulative exposure to area-level risk factors

BACKGROUND

Despite similar incidence rates among Black and White women, breast cancer mortality rates are 40% higher among Black women. More than half of the racial difference in breast cancer mortality can be attributed to triple negative breast cancer (TNBC), an aggressive subtype of invasive breast cancer that disproportionately affects Black women. Recent research has implicated neighborhood conditions in the etiology of TNBC. This study investigated the relationship between cumulative neighborhood-level exposures and TNBC risk.

METHODS

This single-institution retrospective study was conducted on a cohort of 3316 breast cancer cases from New Castle County, Delaware (from 2012 to 2020), an area of the country with elevated TNBC rates. Cases were stratified into TNBC and "Non-TNBC" diagnosis and geocoded by residential address. Neighborhood exposures included census tract-level measures of unhealthy alcohol use, metabolic dysfunction, breastfeeding, and environmental hazards. An overall cumulative risk score was calculated based on tract-level exposures.

RESULTS

Univariate analyses showed each tract-level exposure was associated with greater TNBC odds. In multivariate analyses that controlled for patient-level race and age, tract-level exposures were not associated with TNBC odds. However, in a second multivariate model that included patient-level variables and considered tract-level risk factors as a cumulative exposure risk score, each one unit increase in cumulative exposure was significantly associated with a 10% increase in TNBC odds. Higher cumulative exposure risk scores were found in census tracts with relatively high proportions of Black residents.

CONCLUSIONS

Cumulative exposure to neighborhood-level risk factors that disproportionately affect Black communities was associated with greater TNBC risk.

Multi-Morbidity and Risk of Breast Cancer among Women in the UK Biobank Cohort

(Multi-)Morbidity shares common biological mechanisms or risk factors with breast cancer. This study aimed to investigate the association between the number of morbidities and patterns of morbidity and the risk of female breast cancer. Among 239,436 women (40-69 years) enrolled in the UK Biobank cohort who had no cancer history at baseline, we identified 35 self-reported chronic diseases at baseline. We assigned individuals into morbidity patterns using agglomerative hierarchical clustering analysis. We fitted Cox models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for breast cancer risk. In total, 58.4% of women had at least one morbidity, and the prevalence of multi-morbidity was 25.8%. During a median 7-year follow-up, there was no association between breast cancer risk (5326 cases) and either the number of morbidities or the identified clinically relevant morbidity patterns: no-predominant morbidity (reference), psychiatric morbidities (HR = 1.04, 95%CI 0.94-1.16), respiratory/immunological morbidities (HR = 0.98, 95%CI 0.90-1.07), cardiovascular/metabolic morbidities (HR = 0.93, 95%CI 0.81-1.06), and unspecific morbidities (HR = 0.98, 95%CI 0.89-1.07), overall. Among women younger than 50 years of age only, however, there was a significant association with psychiatric morbidity patterns compared to the no-predominant morbidity pattern (HR = 1.25, 95%CI 1.02-1.52). The other associations did not vary when stratifying by age at baseline and adherence to mammography recommendations. In conclusion, multi-morbidity was not a key factor to help identify patients at an increased risk of breast cancer.

Distinct Reproductive Risk Profiles for Intrinsic-Like Breast Cancer Subtypes: Pooled Analysis of Population-Based Studies

BACKGROUND

Reproductive factors have been shown to be differentially associated with risk of estrogen receptor (ER)-positive and ER-negative breast cancer. However, their associations with intrinsic-like subtypes are less clear.

METHODS

Analyses included up to 23 353 cases and 71 072 controls pooled from 31 population-based case-control or cohort studies in the Breast Cancer Association Consortium across 16 countries on 4 continents. Polytomous logistic regression was used to estimate the association between reproductive factors and risk of breast cancer by intrinsic-like subtypes (luminal A-like, luminal B-like, luminal B-HER2-like, HER2-enriched-like, and triple-negative breast cancer) and by invasiveness. All statistical tests were 2-sided.

RESULTS

Compared with nulliparous women, parous women had a lower risk of luminal A-like, luminal B-like, luminal B-HER2-like, and HER2-enriched-like disease. This association was apparent only after approximately 10 years since last birth and became stronger with increasing time (odds ratio [OR] = 0.59, 95% confidence interval [CI] = 0.49 to 0.71; and OR = 0.36, 95% CI = 0.28 to 0.46 for multiparous women with luminal A-like tumors 20 to less than 25 years after last birth and 45 to less than 50 years after last birth, respectively). In contrast, parous women had a higher risk of triple-negative breast cancer right after their last birth (for multiparous women: OR = 3.12, 95% CI = 2.02 to 4.83) that was attenuated with time but persisted for decades (OR = 1.03, 95% CI = 0.79 to 1.34, for multiparous women 25 to less than 30 years after last birth). Older age at first birth (Pheterogeneity < .001 for triple-negative compared with luminal A-like breast cancer) and breastfeeding (Pheterogeneity < .001 for triple-negative compared with luminal A-like breast cancer) were associated with lower risk of triple-negative breast cancer but not with other disease subtypes. Younger age at menarche was associated with higher risk of all subtypes; older age at menopause was associated with higher risk of luminal A-like but not triple-negative breast cancer. Associations for in situ tumors were similar to luminal A-like.

CONCLUSIONS

This large and comprehensive study demonstrates a distinct reproductive risk factor profile for triple-negative breast cancer compared with other subtypes, with implications for the understanding of disease etiology and risk prediction.

Associations between quantitative measures of TDLU involution and breast tumor molecular subtypes among breast cancer cases in the Black Women's Health Study: a case-case analysis

BACKGROUND

Terminal duct lobular units (TDLUs) are the structures in the breast that give rise to most breast cancers. Previous work has shown that TDLU involution is inversely associated with TDLU metrics, such as TDLU count/100mm2, TDLU span (µm), and number of acini/TDLU, and that these metrics may be elevated in the normal breast tissue of women diagnosed with triple-negative (TN) compared with luminal A breast tumors. It is unknown whether this relationship exists in Black women, who have the highest incidence of TN breast cancer and the highest overall breast cancer mortality rate. We examined relationships between TDLU metrics and breast cancer molecular subtype among breast cancer cases in the Black Women's Health Study (BWHS).

METHODS

We assessed quantitative TDLU metrics (TDLU count/100mm2, TDLU span (µm), and number of acini/TDLU) in digitized 247 hematoxylin and eosin-stained adjacent normal tissue sections from 223 BWHS breast cancer cases, including 65 triple negative (TN) cancers (estrogen receptor (ER) negative, progesterone receptor (PR) negative, human epidermal growth factor-2 (HER2) negative) and 158 luminal A cancers (ER positive, HER2 negative). We evaluated associations of least square mean TDLU metrics adjusted for age and body mass index (BMI) with patient and clinical characteristics. In logistic regression models, we evaluated associations between TDLU metrics and breast cancer subtype, adjusting for age, BMI, and tumor size.

RESULTS

Older age and higher BMI were associated with lower TDLU metrics and larger tumor size and lymph node invasion with higher TDLU metrics. The odds of TN compared with luminal A breast cancer increased with increasing tertiles of TDLU metrics, with odds ratios (95% confidence intervals) for tertile 3 versus tertile 1 of 2.18 (0.99, 4.79), 2.77 (1.07, 7.16), and 1.77 (0.79, 3.98) for TDLU count, TDLU span, and acini count/TDLU, respectively.

CONCLUSION

Associations of TDLU metrics with breast cancer subtypes in the BWHS are consistent with previous studies of White and Asian women, demonstrating reduced TDLU involution in TN compared with luminal A breast cancers. Further investigation is needed to understand the factors that influence TDLU involution and the mechanisms that mediate TDLU involution and breast cancer subtype.

Integrating age, BMI, and serum N-glycans detected by MALDI mass spectrometry to classify suspicious mammogram findings as benign lesions or breast cancer

While mammograms are the standard tool for breast cancer screening, there remains challenges for mammography to effectively distinguish benign lesions from breast cancers, leading to many unnecessary biopsy procedures. A blood-based biomarker could provide a minimally invasive supplemental assay to increase the specificity of breast cancer screening. Serum N-glycosylation alterations have associations with many cancers and several of the clinical characteristics of breast cancer. The current study utilized a high-throughput mass spectrometry workflow to identify serum N-glycans with differences in intensities between patients that had a benign lesion from patients with breast cancer. The overall N-glycan profiles of the two patient groups had no differences, but there were several individual N-glycans with significant differences in intensities between patients with benign lesions and ductal carcinoma in situ (DCIS). Many N-glycans had strong associations with age and/or body mass index, but there were several of these associations that differed between the patients with benign lesions and breast cancer. Accordingly, the samples were stratified by the patient's age and body mass index, and N-glycans with significant differences between these subsets were identified. For women aged 50-74 with a body mass index of 18.5-24.9, a model including the intensities of two N-glycans, 1850.666 m/z and 2163.743 m/z, age, and BMI were able to clearly distinguish the breast cancer patients from the patients with benign lesions with an AUROC of 0.899 and an optimal cutoff with 82% sensitivity and 84% specificity. This study indicates that serum N-glycan profiling is a promising approach for providing clarity for breast cancer screening, especially within the subset of healthy weight women in the age group recommended for mammograms.

Breast Cancer Statistics, 2022

This article is the American Cancer Society's update on female breast cancer statistics in the United States, including population-based data on incidence, mortality, survival, and mammography screening. Breast cancer incidence rates have risen in most of the past four decades; during the most recent data years (2010-2019), the rate increased by 0.5% annually, largely driven by localized-stage and hormone receptor-positive disease. In contrast, breast cancer mortality rates have declined steadily since their peak in 1989, albeit at a slower pace in recent years (1.3% annually from 2011 to 2020) than in the previous decade (1.9% annually from 2002 to 2011). In total, the death rate dropped by 43% during 1989-2020, translating to 460,000 fewer breast cancer deaths during that time. The death rate declined similarly for women of all racial/ethnic groups except American Indians/Alaska Natives, among whom the rates were stable. However, despite a lower incidence rate in Black versus White women (127.8 vs. 133.7 per 100,000), the racial disparity in breast cancer mortality remained unwavering, with the death rate 40% higher in Black women overall (27.6 vs. 19.7 deaths per 100,000 in 2016-2020) and two-fold higher among adult women younger than 50 years (12.1 vs. 6.5 deaths per 100,000). Black women have the lowest 5-year relative survival of any racial/ethnic group for every molecular subtype and stage of disease (except stage I), with the largest Black-White gaps in absolute terms for hormone receptor-positive/human epidermal growth factor receptor 2-negative disease (88% vs. 96%), hormone receptor-negative/human epidermal growth factor receptor 2-positive disease (78% vs. 86%), and stage III disease (64% vs. 77%). Progress against breast cancer mortality could be accelerated by mitigating racial disparities through increased access to high-quality screening and treatment via nationwide Medicaid expansion and partnerships between community stakeholders, advocacy organizations, and health systems.

Associations between circulating proteins and risk of breast cancer by intrinsic subtypes: a Mendelian randomisation analysis

BACKGROUND

The aetiologic role of circulating proteins in the development of breast cancer subtypes is not clear. We aimed to examine the potential causal effects of circulating proteins on the risk of breast cancer by intrinsic-like subtypes within the Mendelian randomisation (MR) framework.

METHODS

MR was performed using summary statistics from two sources: the INTERVAL protein quantitative trait loci (pQTL) Study (1890 circulating proteins and 3301 healthy individuals) and the Breast Cancer Association Consortium (BCAC; 106,278 invasive cases and 91,477 controls). The inverse-variance (IVW)-weighted method was used as the main analysis to evaluate the associations between genetically predicted proteins and the risk of five different intrinsic-like breast cancer subtypes and the weighted median MR method, the Egger regression, the MR-PRESSO, and the MRLocus method were performed as secondary analysis.

RESULTS

We identified 98 unique proteins significantly associated with the risk of one or more subtypes (Benjamini-Hochberg false discovery rate < 0.05). Among them, 51 were potentially specific to luminal A-like subtype, 14 to luminal B/Her2-negative-like, 11 to triple negative, 3 to luminal B-like, and 2 to Her2-enriched-like breast cancer (ntotal = 81). Associations for three proteins (ICAM1, PLA2R1 and TXNDC12) showed evident heterogeneity across the subtypes. For example, higher levels of genetically predicted ICAM1 (per unit of increase) were associated with an increased risk of luminal B/HER2-negative-like cancer (OR = 1.06, 95% CI = 1.03-1.08, BH-FDR = 2.43 × 10-4) while inversely associated with triple-negative breast cancer with borderline significance (OR = 0.97, 95% CI = 0.95-0.99, BH-FDR = 0.065, Pheterogeneity < 0.005).

CONCLUSIONS

Our study found potential causal associations with the risk of subtypes of breast cancer for 98 proteins. Associations of ICAM1, PLA2R1 and TXNDC12 varied substantially across the subtypes. The identified proteins may partly explain the heterogeneity in the aetiology of distinct subtypes of breast cancer and facilitate the personalised risk assessment of the malignancy.

Effectiveness of Organized Mammography Screening for Different Breast Cancer Molecular Subtypes

Simple Summary

We evaluated the short-term effectiveness of a mammography screening program in all women who participated in the screening program and were diagnosed with screen-detected or interval breast cancer (BC) in Flanders (2008–2018). The evaluation was performed for the major molecular subtypes of invasive BC separately and considering the regularity of participation. We found that screen-detected BC was more likely to be diagnosed at early stages than interval BC of luminal, luminal-HER2-positive, and triple-negative BC (TNBC) type, but not for the human epidermal growth factor receptor 2-positive (HER2 positive) subtype. In addition, regular participation was related to a higher likelihood of screening detection than irregular participation for luminal, luminal-HER2-positive, and TNBC, but not for the HER2 positive subtype, either. Our results indicate that regular screening as compared to irregular screening is effective for all breast cancers except for the HER2 subtype.

Abstract

Background: Screening program effectiveness is generally evaluated for breast cancer (BC) as one disease and without considering the regularity of participation, while this might have an impact on detection rate. Objectives: To evaluate the short-term effectiveness of a mammography screening program for the major molecular subtypes of invasive BC. Methods: All women who participated in the screening program and were diagnosed with screen-detected or interval BC in Flanders were included in the study (2008–2018). Molecular subtypes considered were luminal and luminal-HER2-positive, human epidermal growth factor receptor 2-positive, and triple-negative BC (TNBC). The relationship between the BC stage at diagnosis (early (I–II) versus advanced (III–IV)) and the method of detection (screen-detected or interval) and the relationship between the method of detection and participation regularity (regular versus irregular) were evaluated by multi-variable logistic regression models. All models were performed for each molecular subtype and adjusted for age. Results: Among the 12,318 included women, BC of luminal and luminal-HER2-positive subtypes accounted for 70.9% and 11.3%, respectively. Screen-detected BC was more likely to be diagnosed at early stages than interval BC with varied effect sizes for luminal, luminal-HER2-positive, and TNBC with OR:2.82 (95% CI: 2.45–3.25), OR:2.39 (95% CI: 1.77–3.24), and OR:2.29 (95% CI: 1.34–4.05), respectively. Regular participation was related to a higher likelihood of screening detection than irregular participation for luminal, luminal-HER2-positive, and TNBC with OR:1.21 (95% CI: 1.09–1.34), OR: 1.79 (95% CI: 1.38–2.33), and OR: 1.62 (95% CI: 1.10–2.41), respectively. Conclusions: Regular screening as compared to irregular screening is effective for all breast cancers except for the HER2 subtype.

Reproductive history differs by molecular subtypes of breast cancer among women aged ≤ 50 years in Scotland diagnosed 2009–2016: a cross-sectional study

Background

The aetiology of breast cancers diagnosed ≤ 50 years of age remains unclear. We aimed to compare reproductive risk factors between molecular subtypes of breast cancer, thereby suggesting possible aetiologic clues, using routinely collected cancer registry and maternity data in Scotland.

Methods

We conducted a cross-sectional study of 4108 women aged ≤ 50 years with primary breast cancer diagnosed between 2009 and 2016 linked to maternity data. Molecular subtypes of breast cancer were defined using immunohistochemistry (IHC) tumour markers, oestrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor-2 (HER2), and tumour grade. Age-adjusted polytomous logistic regression models were used to estimate odds ratios (OR) and 95% confidence intervals (CI) for the association of number of births, age at first birth and time since last birth with IHC-defined breast cancer subtypes. Luminal A-like was the reference compared to luminal B-like (HER2−), luminal B-like (HER2+), HER2-overexpressed and triple-negative breast cancer (TNBC).

Results

Mean (SD) for number of births, age at first birth and time since last birth was 1.4 (1.2) births, 27.2 (6.1) years and 11.0 (6.8) years, respectively. Luminal A-like was the most common subtype (40%), while HER2-overexpressed and TNBC represented 5% and 15% of cases, respectively. Larger numbers of births were recorded among women with HER2-overexpressed and TNBC compared with luminal A-like tumours (> 3 vs 0 births, OR 1.87, 95%CI 1.18–2.96; OR 1.44, 95%CI 1.07–1.94, respectively). Women with their most recent birth > 10 years compared to < 2 years were less likely to have TNBC tumours compared to luminal A-like (OR 0.63, 95%CI 0.41–0.97). We found limited evidence for differences by subtype with age at first birth.

Conclusion

Number of births and time since last birth differed by molecular subtypes of breast cancer among women aged ≤ 50 years. Analyses using linked routine electronic medical records by molecularly defined tumour pathology data can be used to investigate the aetiology and prognosis of cancer.

Effect of Serum Lipid Profile on the Risk of Breast Cancer: Systematic Review and Meta-Analysis of 1,628,871 Women

Dyslipidemia has been linked to breast cancer incidence. The aim of the present meta-analysis was to further investigate the relationship between the serum lipid profile and breast cancer risk. Databases such as PubMed, EMBASE, and Web of Sciences were searched up to the end of January 2021 using certain MeSH and non-MeSH keywords and combinations to extract related published articles. Twenty-six prospective studies involving 1,628,871 women, of whom 36,590 were diagnosed with breast cancer during the follow-up period met the inclusion criteria. A negative and significant association was found between the HDL-C level and the risk of breast cancer (relative risk (RR): 0.85, 95% CI: 0.72–0.99, I²: 67.6%, p = 0.04). In contrast, TG (RR: 1.02, 95% CI: 0.91–1.13, I²: 54.2%, p = 0.79), total cholesterol (TC) (RR: 0.98, 95% CI: 0.90–1.06, I²: 67.2%, p = 0.57), apolipoprotein A (ApoA) (RR: 0.96, 95% CI: 0.70–1.30, I²: 83.5%, p = 0.78) and LDL-C (RR: 0.93, 95% CI: 0.79–1.09, I²: 0%, p = 0.386) were not associated with breast cancer development. In studies adjusting for hormone use and physical activity, breast cancer risk was positively correlated with TC (RR: 1.05, 95% CI: 1.01–1.10). Similarly, TG was significantly related to breast cancer development after adjustment for baseline lipids (RR: 0.92, 95% CI: 0.85–0.99) and race (any races mentioned in each study) (RR: 1.80, 95% CI: 1.22–2.65). In the present meta-analysis, HDL-C was inversely related to breast cancer risk. Overall, data on the links between lipids and breast cancer are conflicting. However, there is increasing evidence that low HDL-C is related to an increased risk for this type of malignancy.

Mendelian randomization analyses of 23 known and suspected risk factors and biomarkers for breast cancer overall and by molecular subtypes

Many risk factors have been identified for breast cancer. The potential causality for some of them remains uncertain, and few studies have comprehensively investigated these associations by molecular subtypes. We performed a two-sample Mendelian randomization (MR) study to evaluate potential causal associations of 23 known and suspected risk factors and biomarkers with breast cancer risk overall and by molecular subtypes using data from the Breast Cancer Association Consortium. The inverse-variance weighted method was used to estimate odds ratios (OR) and 95% confidence interval (CI) for association of each trait with breast cancer risk. Significant associations with breast cancer risk were found for 15 traits, including age at menarche, age at menopause, body mass index, waist-to-hip ratio, height, physical activity, cigarette smoking, sleep duration, and morning-preference chronotype, and six blood biomarkers (estrogens, insulin-like growth factor-1, sex hormone-binding globulin [SHBG], telomere length, HDL-cholesterol and fasting insulin). Noticeably, an increased circulating SHBG was associated with a reduced risk of estrogen receptor (ER)-positive cancer (OR = 0.83, 95% CI: 0.73-0.94), but an elevated risk of ER-negative (OR = 1.12, 95% CI: 0.93-1.36) and triple negative cancer (OR = 1.19, 95% CI: 0.92-1.54) (P_{heterogeneity}  = 0.01). Fasting insulin was most strongly associated with an increased risk of HER2-negative cancer (OR = 1.94, 95% CI: 1.18-3.20), but a reduced risk of HER2-enriched cancer (OR = 0.46, 95% CI: 0.26-0.81) (P_{heterogeneity}  = 0.006). Results from sensitivity analyses using MR-Egger and MR-PRESSO were generally consistent. Our study provides strong evidence supporting potential causal associations of several risk factors for breast cancer and suggests potential heterogeneous associations of SHBG and fasting insulin levels with subtypes of breast cancer.

Newly identified breast luminal progenitor and gestational stem cell populations likely give rise to HER2-overexpressing and basal-like breast cancers

Breast Cancer (BrC) is a common malignancy with genetically diverse subtypes. There is evidence that specific BrC subtypes originate from particular normal mammary cell populations. However, the cell populations that give rise to most BrC subtypes are unidentified. Several human breast scRNAseq datasets are available. In this research, we utilized a robust human scRNAseq dataset to identify population-specific marker genes and then identified the expression of these marker genes in specific BrC subtypes. In humans, several BrC subtypes, HER2-enriched, basal-like, and triple-negative (TN), are more common in women who have had children. This observation suggests that cell populations that originate during pregnancy give rise to these BrCs. The current human datasets have few normal parous samples, so we supplemented this research with mouse datasets, which contain mammary cells from various developmental stages. This research identified two novel normal breast cell populations that may be the origin of the basal-like and HER2-overexpressing subtypes, respectively. A stem cell-like population, SC, that expresses gestation-specific genes has similar gene expression patterns to basal-like BrCs. A novel luminal progenitor cell population and HER2-overexpressing BrCs are marked by S100A7, S100A8, and S100A9 expression. We bolstered our findings by examining SC gene expression in TN BrC scRNAseq datasets and S100A7-A9 gene expression in BrC cell lines. We discovered that several potential cancer stem cell populations highly express most of the SC genes in TN BrCs and confirmed S100A8 and A9 overexpression in a HER2-overexpressing BrC cell line. In summary, normal SC and the novel luminal progenitor cell population likely give rise to basal-like and HER2-overexpressing BrCs, respectively. Characterizing these normal cell populations may facilitate a better understanding of specific BrCs subtypes.

Socioeconomic, Clinical, and Molecular Features of Breast Cancer Influence Overall Survival of Latin American Women

Molecular profile of breast cancer in Latin-American women was studied in five countries: Argentina, Brazil, Chile, Mexico, and Uruguay. Data about socioeconomic characteristics, risk factors, prognostic factors, and molecular subtypes were described, and the 60-month overall cumulative survival probabilities (OS) were estimated. From 2011 to 2013, 1,300 eligible Latin-American women 18 years or older, with a diagnosis of breast cancer in clinical stage II or III, and performance status ≦̸1 were invited to participate in a prospective cohort study. Face-to-face interviews were conducted, and clinical and outcome data, including death, were extracted from medical records. Unadjusted associations were evaluated by Chi-squared and Fisher's exact tests and the OS by Kaplan-Meier method. Log-rank test was used to determine differences between cumulative probability curves. Multivariable adjustment was carried out by entering potential confounders in the Cox regression model. The OS at 60 months was 83.9%. Multivariable-adjusted death hazard differences were found for women living in Argentina (2.27), Chile (1.95), and Uruguay (2.42) compared with Mexican women, for older (≥60 years) (1.84) compared with younger (≤40 years) women, for basal-like subtype (5.8), luminal B (2.43), and HER2-enriched (2.52) compared with luminal A subtype, and for tumor clinical stages IIB (1.91), IIIA (3.54), and IIIB (3.94) compared with stage IIA women. OS was associated with country of residence, PAM50 intrinsic subtype, age, and tumor stage at diagnosis. While the latter is known to be influenced by access to care, including cancer screening, timely diagnosis and treatment, including access to more effective treatment protocols, it may also influence epigenetic changes that, potentially, impact molecular subtypes. Data derived from heretofore understudied populations with unique geographic ancestry and sociocultural experiences are critical to furthering our understanding of this complexity.

Residential ultraviolet radiation and breast cancer risk in a large prospective cohort

BACKGROUND

Ambient ultraviolet (UV) radiation has been increasing due to climate change. While this may result in adverse health consequences such as an increased incidence of skin cancer, UV radiation is also a source of vitamin D, which has been hypothesized to be protective for breast cancer risk.

METHODS

Using a spatiotemporal kriging model, we estimated residential UV exposure levels for the enrollment addresses (2003-2009) of breast cancer-free women aged 35-74 years participating in the Sister Study and living in the contiguous United States (N = 48,450). Cox proportional hazards models were used to estimate adjusted hazard ratios (HRs) and 95% confidence intervals (95% CIs) for the risk associated with UV exposure levels (mW/m2) categorized in quintiles. We examined the association for breast cancer overall (invasive and ductal carcinoma in situ) and by estrogen receptor (ER) status of the tumor. We considered effect modification by regular (≥4 times/week) vitamin D supplement use.

RESULTS

Over a median of 10.5 years of follow up, 3,510 incident breast cancer diagnoses were reported. We found no evidence of an association between living in areas with higher levels of UV radiation and overall breast cancer risk (HRQ5 vs. Q1 = 1.00, 95% CI: 0.90, 1.11). Higher UV levels were inversely associated with the risk of ER- breast cancer (HRQ5 vs. Q1 = 0.73, 95% CI: 0.55-0.99), but not ER+ (HR Q5 vs. Q1 = 1.04, 95% CI: 0.92-1.18). For ER- breast cancer, the inverse association was only evident in women who did not regularly take vitamin D supplements (HRQ5 vs. Q1 = 0.52, 95% CI: 0.33-0.81) compared with those who did regularly take vitamin D supplements (HRQ5 vs. Q1 = 1.02, 95% CI: 0.68-1.54; p-for-heterogeneity = 0.12).

CONCLUSIONS

The findings from this study support a role for UV exposure and vitamin D in the etiology of ER- breast cancer.

Racial disparities in triple negative breast cancer: toward a causal architecture approach

BACKGROUND

Triple negative breast cancer (TNBC) is an aggressive subtype of invasive breast cancer that disproportionately affects Black women and contributes to racial disparities in breast cancer mortality. Prior research has suggested that neighborhood effects may contribute to this disparity beyond individual risk factors.

METHODS

The sample included a cohort of 3316 breast cancer cases diagnosed between 2012 and 2020 in New Castle County, Delaware, a geographic region of the US with elevated rates of TNBC. Multilevel methods and geospatial mapping evaluated whether the race, income, and race/income versions of the neighborhood Index of Concentration at the Extremes (ICE) metric could efficiently identify census tracts (CT) with higher odds of TNBC relative to other forms of invasive breast cancer. Odds ratios (OR) and 95% confidence intervals (CI) were reported; p-values < 0.05 were significant. Additional analyses examined area-level differences in exposure to metabolic risk factors, including unhealthy alcohol use and obesity.

RESULTS

The ICE-Race, -Income-, and Race/Income metrics were each associated with greater census tract odds of TNBC on a bivariate basis. However, only ICE-Race was significantly associated with higher odds of TNBC after adjustment for patient-level age and race (most disadvantaged CT: OR = 2.09; 95% CI 1.40-3.13), providing support for neighborhood effects. Higher counts of alcohol and fast-food retailers, and correspondingly higher rates of unhealthy alcohol use and obesity, were observed in CTs that were classified into the most disadvantaged ICE-Race quintile and had the highest odds of TNBC.

CONCLUSION

The use of ICE can facilitate the monitoring of cancer inequities and advance the study of racial disparities in breast cancer.

TP53 Pathway Function, Estrogen Receptor Status, and Breast Cancer Risk Factors in the Carolina Breast Cancer Study

BACKGROUND

TP53 and estrogen receptor (ER) both play essential roles in breast cancer development and progression, with recent research revealing cross-talk between TP53 and ER signaling pathways. Although many studies have demonstrated heterogeneity of risk factor associations across ER subtypes, associations by TP53 status have been inconsistent.

METHODS

This case-case analysis included incident breast cancer cases (47% Black) from the Carolina Breast Cancer Study (1993-2013). Formalin-fixed paraffin-embedded tumor samples were classified for TP53 functional status (mutant-like/wild-type-like) using a validated RNA signature. For IHC-based TP53 status, mutant-like was classified as at least 10% positivity. We used two-stage polytomous logistic regression to evaluate risk factor heterogeneity due to RNA-based TP53 and/or ER, adjusting for each other and for PR, HER2, and grade. We then compared this with the results when using IHC-based TP53 classification.

RESULTS

The RNA-based classifier identified 55% of tumors as TP53 wild-type-like and 45% as mutant-like. Several hormone-related factors (oral contraceptive use, menopausal status, age at menopause, and pre- and postmenopausal body mass index) were associated with TP53 mutant-like status, whereas reproductive factors (age at first birth and parity) and smoking were associated with ER status. Multiparity was associated with both TP53 and ER. When classifying TP53 status using IHC methods, no associations were observed with TP53. Associations observed with RNA-based TP53 remained after accounting for basal-like subtype.

CONCLUSIONS

This case-case study found breast cancer risk factors associated with RNA-based TP53 and ER.

IMPACT

RNA-based TP53 and ER represent an emerging etiologic schema of interest in breast cancer prevention research.

First Evidence for a Role of Siglec-8 in Breast Cancer

Sialic acid-binding immunoglobulin-like lectins (Siglecs) are involved in various immune cell-mediated diseases. Their role in cancer is poorly investigated, and research focusses on Siglec-expression on immune cells interacting with tumor cells. This study evaluates the role of Siglec-8 in breast cancer (BC). Siglec-8 expression was analyzed immunohistochemically on 235 primary BC cases and was correlated with clinical and pathological parameters and outcome. Cell culture experiments were performed with various BC cell lines. Siglec-8 was expressed in 215 BC cases and expression was lowest in triple-negative BC. It correlated with estrogen receptor-status, grading and the prognostic factors galectin (Gal)-7 and tumor-associated mucin-1 (TA-MUC1). However, Gal-7 and TA-MUC1 were only prognosticators for clinical outcome in the cohort expressing high (Immunoreactivity score IRS > 3) Siglec-8 levels but not in the low-expressing cohort. Siglec-8 knockdown led to a significantly reduced Gal-7 expression in MCF7 cells. All BC cell lines expressed low Siglec-8-levels, that could be elevated in MCF7 by Peroxisome proliferator-activated receptor (PPARγ)-stimulation. This study demonstrates that Siglec-8 is expressed in BC cells and correlates with known clinical and prognostic parameters. It is probably associated with Gal-7 and TA-MUC1 and might be regulated via PPARγ. Further analyses focusing on functional associations will clarify Siglec-8’s eligibility as a possible therapeutic target.

Breath biopsy of breast cancer using sensor array signals and machine learning analysis

Breast cancer causes metabolic alteration, and volatile metabolites in the breath of patients may be used to diagnose breast cancer. The objective of this study was to develop a new breath test for breast cancer by analyzing volatile metabolites in the exhaled breath. We collected alveolar air from breast cancer patients and non-cancer controls and analyzed the volatile metabolites with an electronic nose composed of 32 carbon nanotubes sensors. We used machine learning techniques to build prediction models for breast cancer and its molecular phenotyping. Between July 2016 and June 2018, we enrolled a total of 899 subjects. Using the random forest model, the prediction accuracy of breast cancer in the test set was 91% (95% CI: 0.85–0.95), sensitivity was 86%, specificity was 97%, positive predictive value was 97%, negative predictive value was 97%, the area under the receiver operating curve was 0.99 (95% CI: 0.99–1.00), and the kappa value was 0.83. The leave-one-out cross-validated discrimination accuracy and reliability of molecular phenotyping of breast cancer were 88.5 ± 12.1% and 0.77 ± 0.23, respectively. Breath tests with electronic noses can be applied intraoperatively to discriminate breast cancer and molecular subtype and support the medical staff to choose the best therapeutic decision.

Breast cancer risk factors by mode of detection among screened women in the Cancer Prevention Study-II

BACKGROUND

Identifying risk factors for women at high risk of symptom-detected breast cancers that were missed by screening would enable targeting of enhanced screening regimens. To this end, we examined associations of breast cancer risk factors by mode of detection in screened women from the Cancer Prevention Study (CPS)-II Nutrition Cohort.

METHODS

Among 77,206 women followed for a median of 14.8 years, 2711 screen-detected and 1281 symptom-detected breast cancer cases were diagnosed. Multivariable-adjusted associations were estimated using joint Cox proportional hazards regression models with person-time calculated contingent on screening.

RESULTS

Factors associated with higher risks of symptom-detected and screen-detected breast cancer included current combined hormone therapy (HT) use (HR 2.07, 95% CI 1.72-2.48 and 1.45, 1.27-1.65, respectively) and history of benign breast disease (1.85, 1.64-2.08 and 1.43, 1.31-1.55, respectively). Current estrogen-only HT use was associated with symptom-detected (1.40, 1.15-1.71) but not screen-detected (0.95, 0.83-1.09) breast cancer. Higher risk of screen-detected but not symptom-detected breast cancer was observed for obese vs. normal body mass index (1.22, 1.01-1.48 and 0.76, 0.56-1.01, respectively), per 3 h/day sitting time (1.10, 1.04-1.16 and 0.97, 0.89-1.06, respectively), and ≥ 2 drinks per day vs. nondrinker (1.40, 1.16-1.69 and 1.27, 0.97-1.66, respectively).

CONCLUSIONS

Differences in risk factors for symptom-detected vs. screen-detected breast cancer were observed and most notably, use of combined and estrogen-only HT and a history of benign breast disease were associated with increased risk of symptomatic detected breast cancer.

IMPACT

If confirmed, these data suggest that such women may benefit from more intensive screening to facilitate early detection.

Body size and weight change over adulthood and risk of breast cancer by menopausal and hormone receptor status: a pooled analysis of 20 prospective cohort studies

Associations between anthropometric factors and breast cancer (BC) risk have varied inconsistently by estrogen and/or progesterone receptor (ER/PR) status. Associations between prediagnostic anthropometric factors and risk of premenopausal and postmenopausal BC overall and ER/PR status subtypes were investigated in a pooled analysis of 20 prospective cohorts, including 36,297 BC cases among 1,061,915 women, using multivariable Cox regression analyses, controlling for reproductive factors, diet and other risk factors. We estimated dose-response relationships and tested for nonlinear associations using restricted cubic splines. Height showed positive, linear associations for premenopausal and postmenopausal BC risk (6-7% RR increase per 5 cm increment), with stronger associations for receptor-positive subtypes. Body mass index (BMI) at cohort baseline was strongly inversely associated with premenopausal BC risk, and strongly positively-and nonlinearly-associated with postmenopausal BC (especially among women who never used hormone replacement therapy). This was primarily observed for receptor-positive subtypes. Early adult BMI (at 18-20 years) showed inverse, linear associations for premenopausal and postmenopausal BC risk (21% and 11% RR decrease per 5 kg/m2, respectively) with stronger associations for receptor-negative subtypes. Adult weight gain since 18-20 years was positively associated with postmenopausal BC risk, stronger for receptor-positive subtypes, and among women who were leaner in early adulthood. Women heavier in early adulthood generally had reduced premenopausal BC risk, independent of later weight gain. Positive associations between height, baseline (adult) BMI, adult weight gain and postmenopausal BC risk were substantially stronger for hormone receptor-positive versus negative subtypes. Premenopausal BC risk was positively associated with height, but inversely with baseline BMI and weight gain (mostly in receptor-positive subtypes). Inverse associations with early adult BMI seemed stronger in receptor-negative subtypes of premenopausal and postmenopausal BC.

Validation of plasma metabolites associated with breast cancer risk among Mexican Americans

In our previous breast cancer case control study in Hispanics, we found 14 metabolites whose levels differed between cases and controls. To validate the results, we carried out a nested case control study of 100 incident breast cancer and 100 matched healthy women identified from the Mano-A-Mano Mexican American Cohort study. With the adjustment of parity, education, birth place, language acculturation, BMI category, smoking, drinking, physical activity, and sitting time, 4 metabolites were associated with breast cancer risk: 3-hydroxyoctanoate (Odds ratio (OR) = 1.51, 95% confidence interval (CI): 1.10, 3.47), 3-hydroxybutyrate (BHBA) (OR = 1.42, 95%CI: 1.01, 3.72), linoleate (18:2n6) (OR = 1.39, 95% CI: 1.07, 4.04), and bilirubin (OR = 0.54, 95%CI: 0.42, 0.95). Then, we used 3 non-redundant metabolites, namely 3-hydroxyoctanoate, linoleate (18:2n6), and bilirubin, to generate a metabolic risk score. Increased metabolites risk score was associated with a 1.67-fold increased risk of breast cancer (OR = 1.67, 95%CI: 1.32, 3.94). And the significant association was more evident among those who were diagnosed with cancer earlier during the follow-up (≤ 5 years) than their counterparts. In conclusion, we identified four significant metabolites which may help elucidate metabolic pathways that contribute to breast carcinogenesis. Our findings warrant further replication efforts.

Pubertal timing and breast cancer risk in the Sister Study cohort

Background

Earlier age at menarche is an established risk factor for breast cancer. While age at menarche has been fairly stable over the past half-century, age at breast development (thelarche) has continued to decrease. Recently, earlier age at thelarche and a longer time between thelarche and menarche (pubertal tempo) were shown to be associated with increased breast cancer risk. Our objective was to examine how breast cancer risk was associated with pubertal timing and tempo in a prospective US cohort.

Methods

Women ages 35–74 years without a history of breast cancer, but who had a sister previously diagnosed with breast cancer, were enrolled in the Sister Study from 2003 to 2009 (N = 50,884). At enrollment, participants reported their ages at thelarche and menarche. Pubertal tempo was age at menarche minus age at thelarche. We estimated adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for each pubertal milestone and risk of breast cancer (invasive or ductal carcinoma in situ) using Cox proportional hazards regression. We examined whether associations between age at thelarche and breast cancer risk were modified by birth cohort, race/ethnicity, weight at age 10, and extent of breast cancer family history, as characterized by a Bayesian score based on first-degree family structure.

Results

During follow-up (mean = 9.3 years), 3295 eligible women were diagnosed with breast cancer. Early ages at thelarche (HR = 1.23, 95% CI 1.03–1.46 for < 10 vs. 12–13 years) and menarche (HR = 1.10, 95% CI 1.01–1.20 for < 12 vs. 12–13 years) were positively associated with breast cancer risk. Pubertal tempo was not associated with breast cancer risk (HR = 0.99, 95% CI 0.97–1.02 per 1-year longer tempo). When considering early thelarche (< 10 years) and early menarche (< 12 years) jointly, women with both had a 30% greater risk of breast cancer compared with women with neither risk factor (95% CI 1.07–1.57). The association between age at thelarche and breast cancer risk did not significantly vary by birth cohort, race/ethnicity, childhood weight, or Bayesian family history score.

Conclusions

Earlier ages at thelarche and menarche may enhance susceptibility to breast carcinogenesis. Age at thelarche is an important risk factor to consider given secular trends towards earlier development.

Dietary effects on breast cancer molecular subtypes, a 1:2 paired case-control study

To explore the associations between dietary factors and breast cancer (BC) molecular subtypes. The retrospective cases were confirmed by pathological diagnosis with breast cancer were gathered in two major hospitals in Xuzhou city, China, from 2015 to 2016. These cases were classified by the meeting standard of 13th St Gallen: luminal A, luminal B, Her-2 overexpression, and triple-negative breast cancer (TNBC) subtypes. A 1:2 paired retrospective case-control study with 210 cases and 420 controls was conducted to evaluate individual dietary intake, by food frequency questionnaire (FFQ) and estimate odds ratios (ORs), by the Cox regression model. For overall breast cancer patients, the more frequency of red meat (OR = 1.002, 95% CI = 1.001-1.004) and salted food (OR = 1.003, 95% CI = 1.001-1.005) were statistically significantly associated with a greater risk of breast cancer. Beans (OR = 0.997, 95% CI = 0.995-0.999), white meat (OR = 0.993, 95% CI = 0.989-0.997), aquatic products (OR = 0.990, 95% CI = 0.984-0.996), vegetables (OR = 0.999, 95% CI = 0.999-0.999), fruit (OR = 0.998, 95% CI = 0.997-0.999), and green tea (OR = 0.997, 95% CI = 0.994-0.999) were significantly associated with a lower risk of breast cancer. For luminal breast cancer patients, beans (OR = 0.997, 95% CI = 0.994-0.999), white meat (OR = 0.992, 95% CI = 0.987-0.997), green tea (OR = 0.995, 95% CI = 0.991-0.999), and milk (OR = 0.998, 95% CI = 0.996-0.999) were protective factors. While for nonluminal breast cancer, red meat was not included in the equation, and beans (OR = 0.989, 95% CI = 0.981-0.997), white meat (OR = 0.989, 95% CI = 0.981-0.998), vegetables (OR = 0.998, 95% CI = 0.997-0.999), and milk (OR = 0.994, 95% CI = 0.989-0.999) still showed a significantly reduced risk of nonluminal breast cancer. Different dietary factors revealed different effects on the etiology of breast cancer. Red meat may be a specific risk factor for luminal-type breast cancer.

Logistic LASSO Regression for Dietary Intakes and Breast Cancer

A multitude of dietary factors from dietary fat to macro and micronutrients intakes have been associated with breast cancer, yet data are still equivocal. Therefore, utilizing data from the large, multi-year, cross-sectional National Health and Nutrition Examination Survey (NHANES), we applied a novel, modern statistical shrinkage technique, logistic least absolute shrinkage and selection operator (LASSO) regression, to examine the association between dietary intakes in women, ≥50 years, with self-reported breast cancer (n = 286) compared with women without self-reported breast cancer (1144) from the 1999–2010 NHANES cycle. Logistic LASSO regression was used to examine the relationship between twenty-nine variables, including dietary variables from food, as well as well-established/known breast cancer risk factors, and to subsequently identify the most relevant variables associated with self-reported breast cancer. We observed that as the penalty factor (λ) increased in the logistic LASSO regression, well-established breast cancer risk factors, including age (β = 0.83) and parity (β = −0.05) remained in the model. For dietary macro and micronutrient intakes, only vitamin B12 (β = 0.07) was positively associated with self-reported breast cancer. Caffeine (β = −0.01) and alcohol (β = 0.03) use also continued to remain in the model. These data suggest that a diet high in vitamin B12, as well as alcohol use may be associated with self-reported breast cancer. Nonetheless, additional prospective studies should apply more recent statistical techniques to dietary data and cancer outcomes to replicate and confirm the present findings.

Relationships between Breast Feeding and Breast Cancer Subtypes: Lessons Learned from Studies in Humans and in Mice

There are differential risk relationships between parity and breast cancer according to estrogen receptor (ER) status, with an increased risk of ER^- disease reduced by breastfeeding. This may be particularly relevant for understanding the higher incidence of ER^- tumors in Black women, who are more likely to be parous and less likely to breastfeed than other U.S. groups. Potential mechanisms for these relationships may include effects of disordered breast involution on inflammatory milieu in the breast as well as epigenetic reprogramming in the mammary gland, which can affect cell fate decisions in progenitor cell pools. In normal breast tissue, parity has been associated with hypermethylation of FOXA1, a pioneer transcription factor that promotes the luminal phenotype in luminal progenitors, while repressing the basal phenotype. In breast tumors, relationships between FOXA1 methylation and parity were strongest among women who did not breastfeed. Here, we summarize the epidemiologic literature regarding parity, breastfeeding, and breast cancer subtypes, and review potential mechanisms whereby these factors may influence breast carcinogenesis, with a focus on effects on progenitor cell pools in the mammary gland.

Incidence Trends of Breast Cancer Molecular Subtypes by Age and Race/Ethnicity in the US From 2010 to 2016

IMPORTANCE

Breast cancer incidence trends by age and race/ethnicity have been documented; it is less clear whether incidence trends of breast cancer molecular subtypes, which differ in risk factors and prognosis, also vary by age and race/ethnicity.

OBJECTIVE

To estimate annual percentage changes and trends in breast cancer molecular subtype-specific incidence rates by age at diagnosis and race/ethnicity in the US.

DESIGN, SETTING, AND PARTICIPANTS

This population-based cross-sectional study included data from 18 cancer registries in the Surveillance, Epidemiology and End Results database, capturing 27.8% of the US population. Hispanic and non-Hispanic White, Black, and Asian/Pacific Islander women aged 25 to 84 years who were diagnosed with invasive breast cancer from 2010 to 2016 were included. Data were analyzed from September 2019 to February 2020.

EXPOSURES

Age and racial/ethnic groups.

MAIN OUTCOMES AND MEASURES

Annual percentage change (APC) and 95% CIs for age-standardized breast cancer incidence rates stratified by 15-year age groups at diagnosis and race/ethnicity.

RESULTS

Of 320 124 women diagnosed with breast cancer from 2010 to 2016, 232 558 (72.6%) had luminal A, 35 869 (11.2%) had luminal B, 15 472 (4.8%) had ERBB2-enriched, and 36 225 (11.3%) had triple-negative breast cancer subtypes. Luminal A breast cancer incidence rates increased in non-Hispanic White (APC from 2010-2014, 2.3%; 95% CI, 0.3% to 4.2%) and non-Hispanic Asian/Pacific Islander (APC from 2010-2016, 2.5%; 95% CI, 0.6% to 4.5%) women aged 40 to 54 years, and in non-Hispanic Black women aged 55 to 69 years women (APC from 2010-2012, 4.9%; 95% CI, 4.0% to 5.7%). Luminal B breast cancer incidence rates increased in all age groups for non-Hispanic White women (age 25-39 years: APC, 4.3%; 95% CI, 1.5% to 7.%2; age 40-54 years: APC, 3.5%; 95% CI, 1.4% to 5.6%; age 55-69 years: APC, 3.3%; 95% CI, 1.6% to 5.0%; age 70-84 years: APC, 3.9%; 95% CI, 1.9% to 6.0%) and Hispanic women (age 25-39 years: APC, 8.4%; 95% CI, 5.8% to 11.2%; age 40-54 years: APC, 6.1%; 95% CI, 4.2% to 8.0%; age 55-69 years: APC, 5.1%; 95% CI, 1.5% to 8.8%; age 70-84 years: APC, 7.1%; 95% CI, 4.6% to 9.6%) and in non-Hispanic Asian/Pacific Islander women aged 55 to 69 years (APC, 6.1%; 95% CI, 3.2% to 9.0%). ERBB2-enriched breast cancer incidence rates increased in non-Hispanic White women aged 25 to 39 years (APC, 4.7%; 95% CI, 1.5% to 8.0%). Triple-negative breast cancer incidence rates decreased in non-Hispanic White women aged 40 to 54 years (APC, -2.3%; 95% CI, -3.8% to -0.7%) and 55 to 69 years (APC, -3.6%; 95% CI, -5.1% to -2.1%) and in non-Hispanic Black women aged 55 to 69 years (APC, -1.4%; 95% CI, -2.2% to -0.7%).

CONCLUSIONS AND RELEVANCE

The findings of this cross-sectional study suggest that between 2010 and 2016, luminal A and luminal B breast cancer incidence rates increased for many racial/ethnic and age groups, with the largest increases observed for luminal B breast cancer. ERBB2-enriched breast cancer incidence rates increased for young non-Hispanic White women, while triple-negative breast cancer incidence rates decreased for midlife non-Hispanic White and non-Hispanic Black women. These trends may suggest changes in breast cancer risk factor profiles across age and racial/ethnic groups.

Divergent breast cancer incidence trends by hormone receptor status in the state of Sarawak, Malaysia

Recent studies from high-risk countries such as the US, Denmark and Ireland have shown rising incidence rates of hormone receptor (HR)-positive and falling rates of HR-negative breast cancers (BC). However, it remains unclear whether a similar pattern occurs in low-risk countries. Detailed clinical and risk factor data were collected from 2,977 female invasive BC patients (≥20 years) in Sarawak General Hospital, Malaysia, representing 93% of the population. The population-at-risk was obtained from the Department of Statistics Malaysia. Secular trends in age-standardized incidence rates were assessed using estimated average annual percent changes. Associations between established BC risk factors and tumor subtypes defined by HR or joint human epidermal growth factor receptor 2 (HR/HER2) status were examined by case-case comparisons using logistic regression. From 2006 to 2015, incidence rates increased for HR-positive cancers by 4.46%/year (95% CI = 2.19-6.78) and decreased for HR-negative cancers by 2.29%/year (95% CI = -4.31 to -0.24). When further stratified by HER2, the most contrasting difference in linear trends was observed between HR+/HER2- and HR-/HER2- subtypes. After controlling for potential confounders, cases with excess body weight (OR_{overweight vs. normal} = 0.82; 95% CI = 0.69-0.98; OR_{obese vs. normal} = 0.62; 95% CI = 0.48-0.80), later age at first birth (OR_{≥26 years vs. <23 years} = 0.82; 95% CI = 0.66-1.02), nulliparity (OR_{nulliparous vs. <23 years} = 0.74; 95% CI = 0.59-0.94) and never-breastfeeding (OR_{never vs. ever} = 0.73; 95% CI = 0.55-0.97) were less frequent among HR-negative cases than among HR-positive cases. Diverging incidence trends by HR expression were similar in Sarawak and Western countries, possibly reflecting changes in the prevalence of risk factors with opposing effects by tumor subtypes in low- and high-risk populations.

Gut microbiome associations with breast cancer risk factors and tumor characteristics: a pilot study

OBJECTIVE

To investigate the association between gut microbiome with breast tumor characteristics (receptor status, stage and grade) and known breast cancer risk factors.

METHODS

In a pilot cross-sectional study of 37 incident breast cancer patients, fecal samples collected prior to chemotherapy were analyzed by 16S ribosomal RNA (rRNA) gene-based sequencing protocol. Alpha diversity and specific taxa by tumor characteristics and breast cancer risk factors were tested by Wilcoxon rank sum test, and by differential abundance analysis, using a zero-inflated negative binomial regression model with adjustment for total counts, age and race/ethnicity.

RESULTS

There were no significant alpha diversity or phyla differences by estrogen/progesterone receptor status, tumor grade, stage, parity and body mass index. However, women with human epidermal growth factor receptor 2 positive (HER2+) (n = 12) compared to HER2- (n = 25) breast cancer showed 12-23% lower alpha diversity [number of species (OTU) p = 0.033, Shannon index p = 0.034], lower abundance of Firmicutes (p = 0.005) and higher abundance of Bacteroidetes (p = 0.089). Early menarche (ages ≤ 11) (n = 11) compared with later menarche (ages ≥ 12) (n = 26) was associated with lower OTU (p = 0.036), Chao1 index (p = 0.020) and lower abundance of Firmicutes (p = 0.048). High total body fat (TBF) (> 46%) (n = 12) compared to lower (≤ 46%) TBF was also associated with lower Chao 1 index (p = 0.011). There were other significant taxa abundance differences by HER2 status, menarche age, as well as other tumor and breast cancer risk factors.

CONCLUSIONS AND RELEVANCE

Further studies are needed to identify characteristics of the human microbiome and the interrelationships between breast cancer hormone receptor status and established breast cancer risk factors.

The Use Of Genetic Correlation And Mendelian Randomization Studies To Increase Our Understanding of Relationships Between Complex Traits

PURPOSE OF THE REVIEW

Increasing access to large-scale genetic datasets in population-based studies allows for genetic association studies as a means to examine previously known and novel relationships among complex traits. In this review, we discuss two widely used approaches to leverage genetic data to study the links between traits: Genome-wide genetic correlation and Mendelian Randomization (MR) studies.

RECENT FINDINGS

Both genetic correlation and MR studies have provided important novel insights. However, although they are less sensitive to many sources of bias present in traditional, observational epidemiology, they still rely on assumptions that in practice might be difficult to assess. To overcome this, development of novel methods less sensitive to these assumptions is an active area of research.

SUMMARY

We believe that as population-based genetic datasets grow larger and novel methods allowing for weaker forms of current assumptions become available, genetic correlation and MR studies will become an integral part of genetic epidemiology studies.