Perimenopausal and Menopausal Mammary Glands In A 4-Vinylcyclohexene Diepoxide Mouse Model.

As both perimenopausal and menopausal periods are recognized critical windows of susceptibility for breast carcinogenesis, development of a physiologically relevant model has been warranted. The traditional ovariectomy model causes instant removal of the entire hormonal repertoire produced by the ovary, which does not accurately approximate human natural menopause with gradual transition. Here, we characterized the mammary glands of 4-vinylcyclohexene diepoxide (VCD)-treated animals at different time points, revealing that the model can provide the mammary glands with both perimenopausal and menopausal states. The perimenopausal gland showed moderate regression in ductal structure with no responsiveness to external hormones, while the menopausal gland showed severe regression with hypersensitivity to hormones. Leveraging the findings on the VCD model, effects of a major endocrine disruptor (polybrominated diphenyl ethers, PBDEs) on the mammary gland were examined during and after menopausal transition, with the two exposure modes; low-dose, chronic (environmental) and high-dose, subacute (experimental). All conditions of PBDE exposure did not augment or compromise the macroscopic ductal reorganization resulting from menopausal transition and/or hormonal treatments. Single-cell RNA sequencing revealed that the experimental PBDE exposure during the post-menopausal period caused specific transcriptomic changes in the non-epithelial compartment such as Errfi1 upregulation in fibroblasts. The environmental PBDE exposure resulted in similar transcriptomic changes to a lesser extent. In summary, the VCD mouse model provides both perimenopausal and menopausal windows of susceptibility for the breast cancer research community. PBDEs, including all tested models, may affect the post-menopausal gland including impacts on the non-epithelial compartments.

Risk-reducing mastectomy and breast cancer mortality in women with a BRCA1 or BRCA2 pathogenic variant: an international analysis.

BACKGROUND: Risk-reducing mastectomy (RRM) is offered to women with a BRCA1 or BRCA2 pathogenic variant, however, there are limited data on the impact on breast cancer mortality. METHODS: Participants were identified from a registry of women with BRCA1/2 pathogenic variants. We used a pseudo-randomised trial design and matched one woman with a RRM to one woman without a RRM on year of birth, gene, and country. We estimated the hazard ratio (HR) and 95% confidence intervals (CI) for dying of breast cancer in the follow-up period. RESULTS: There were 1654 women included; 827 assigned to the RRM arm and 827 assigned to the control arm. After a mean follow-up of 6.3 years, there were 20 incident breast cancers (including 15 occult cancers) and two breast cancer deaths in the RRM arm, and 100 incident breast cancers and 7 breast cancer deaths in the control arm (HR = 0.26; 95% CI 0.05-1.35; p = 0.11). The probability of dying of breast cancer within 15 years after RRM was 0.95%. CONCLUSIONS: In women with a BRCA1 or BRCA2 pathogenic variant, RRM reduces the risk of breast cancer, and the probability of dying of breast cancer is low.

The risk of skin cancer in women who carry BRCA1 or BRCA2 mutations.

BACKGROUND: It has not been clearly established if skin cancer or melanoma are manifestations of BRCA1 or BRCA2 mutation carrier status. Estimating the risk of skin cancer is an important step towards developing screening recommendations. METHODS: We report the findings of a prospective cohort study of 6,207 women from North America who carry BRCA1 or BRCA2 mutations. Women were followed from the date of baseline questionnaire to the diagnosis of skin cancer, to age 80 years, death from any cause, or the date of last follow-up. RESULTS: During the mean follow-up period of eight years, 3.7% of women with a BRCA1 mutation (133 of 3,623) and 3.8% of women with a BRCA2 mutation (99 of 2,584) reported a diagnosis of skin cancer (including both keratinocyte carcinomas and melanoma). The cumulative risk of all types of skin cancer from age 20 to 80 years was 14.1% for BRCA1 carriers and 10.7% for BRCA2 carriers. The cumulative risk of melanoma was 2.5% for BRCA1 carriers and 2.3% for BRCA2 carriers, compared to 1.5% for women in the general population in the United States. The strongest risk factor for skin cancer was a prior diagnosis of skin cancer. CONCLUSION: The risk of non-melanoma skin cancer in women who carry a mutation in BRCA1 or BRCA2 is similar to that of non-carrier women. The risk of melanoma appears to be slightly elevated. We suggest that a referral to a dermatologist or primary care provider for BRCA mutation carriers for annual skin examination and counselling regarding limiting UV exposure, the use of sunscreen and recognizing the early signs of melanoma might be warranted, but further studies are necessary.

The risks of cancer in older women with BRCA pathogenic variants: How far have we come?

BACKGROUND: The purpose of this study was to estimate the cumulative risks of all cancers in women from 50 to 75 years of age with a BRCA1 or BRCA2 pathogenic variant. METHODS: Participants were women with BRCA1 or BRCA2 pathogenic variants from 85 centers in 16 countries. Women were eligible if they had no cancer before the age of 50 years. Participants completed a baseline questionnaire and follow-up questionnaires every 2 years. Women were followed from age 50 until a diagnosis of cancer, death, age 75, or last follow-up. The risk of all cancers combined from age 50 to 75 was estimated using the Kaplan-Meier method. RESULTS: There were 2211 women included (1470 BRCA1 and 742 BRCA2). There were 379 cancers diagnosed in the cohort between 50 and 75 years. The actuarial risk of any cancer from age 50 to 75 was 49% for BRCA1 and 43% for BRCA2. Breast (n = 186) and ovarian (n = 45) were the most frequent cancers observed. For women who had both risk-reducing mastectomy and bilateral salpingo-oophorectomy before age 50, the risk of developing any cancer between age 50 and 75 was 9%. CONCLUSION: Women with a BRCA1 or BRCA2 pathogenic variant have a high risk of cancer between the ages of 50 and 75 years and should be counselled appropriately.

Ovarian cancer pathology characteristics as predictors of variant pathogenicity in BRCA1 and BRCA2.

BACKGROUND: The distribution of ovarian tumour characteristics differs between germline BRCA1 and BRCA2 pathogenic variant carriers and non-carriers. In this study, we assessed the utility of ovarian tumour characteristics as predictors of BRCA1 and BRCA2 variant pathogenicity, for application using the American College of Medical Genetics and the Association for Molecular Pathology (ACMG/AMP) variant classification system. METHODS: Data for 10,373 ovarian cancer cases, including carriers and non-carriers of BRCA1 or BRCA2 pathogenic variants, were collected from unpublished international cohorts and consortia and published studies. Likelihood ratios (LR) were calculated for the association of ovarian cancer histology and other characteristics, with BRCA1 and BRCA2 variant pathogenicity. Estimates were aligned to ACMG/AMP code strengths (supporting, moderate, strong). RESULTS: No histological subtype provided informative ACMG/AMP evidence in favour of BRCA1 and BRCA2 variant pathogenicity. Evidence against variant pathogenicity was estimated for the mucinous and clear cell histologies (supporting) and borderline cases (moderate). Refined associations are provided according to tumour grade, invasion and age at diagnosis. CONCLUSIONS: We provide detailed estimates for predicting BRCA1 and BRCA2 variant pathogenicity based on ovarian tumour characteristics. This evidence can be combined with other variant information under the ACMG/AMP classification system, to improve classification and carrier clinical management.

Tamoxifen and the risk of breast cancer in women with a BRCA1 or BRCA2 mutation.

PURPOSE: Chemoprevention with a selective estrogen receptor modulator (tamoxifen or raloxifene) is a non-surgical option offered to high-risk women to reduce the risk of breast cancer. The evidence for tamoxifen benefit is based on trials conducted among predominantly postmenopausal women from the general population and on studies of contralateral breast cancer in women with a pathogenic variant (mutation hereafter) in BRCA1 or BRCA2. Tamoxifen has not been assessed as a primary prevention agent in women with an inherited BRCA mutation. METHODS: We conducted a prospective analysis of tamoxifen chemoprevention and the risk of breast cancer in women with a BRCA1 or BRCA2 mutation. Data on tamoxifen (and raloxifene) use was collected by questionnaire and updated biennially. Information on incident cancers was collected by self-report and was confirmed by medical record review. In a matched analysis, we estimated the hazard ratio (HR) and 95% confidence intervals (CI) for developing a first primary breast cancer associated with tamoxifen or raloxifene use, using Cox proportional hazards analysis. RESULTS: There were 4578 unaffected women in the cohort, of whom 137 reported tamoxifen use (3%), 83 reported raloxifene use (2%) and 12 used both drugs (0.3%). Women who used tamoxifen or raloxifene were matched 1:3 with women who used neither drug on year of birth, country of residence, year of study entry and gene (BRCA1 or BRCA2). We generated 202 matched pairs. After a mean follow-up of 6.8 years, there were 22 incident breast cancers diagnosed among tamoxifen/raloxifene users (10.9% of users) and 71 cases diagnosed among non-users (14.3% of non-users; HR = 0.64; 95% CI 0.40-1.03; P = 0.07). CONCLUSION: Chemoprevention may be an effective risk-reduction option for BRCA mutation carriers, but further studies with longer follow-up are necessary.

Promotores' perspectives on the virtual adaptation of a hereditary breast cancer education program.

Breast cancer is the most common cancer in women in the United States (U.S.) and the leading cause of cancer related death among U.S. Hispanics/Latinas (H/Ls). H/Ls have lower rates of screening and longer time to follow up after an abnormal mammogram. We developed a comprehensive community health educator (promotores)-led education and risk identification program for Spanish-speaking H/Ls in California to increase mammography screening, genetic testing, and the understanding of the impact of family history on cancer risk. Due to COVID-19, we adapted the program to a virtual platform. The experience of transforming the program to a virtual platform provided unique opportunities for collaboration between researchers, community partners, and participants. Promotores are major partners in community based participatory research and in the provision of health care services, but their voices are often excluded from scientific reports. This commentary is an effort to provide a platform for promotores to share their experiences and for the readers to understand their approach in bridging the gap between health care services and communities.

Differences in somatic TP53 mutation type in breast tumors by race and receptor status.

PURPOSE: Somatic driver mutations in TP53 are associated with triple-negative breast cancer (TNBC) and poorer outcomes. Breast cancers in women of African ancestry (AA) are more likely to be TNBC and have somatic TP53 mutations than cancers in non-Hispanic White (NHW) women. Missense driver mutations in TP53 have varied functional impact including loss-of-function (LOF) or gain-of-function (GOF) activity, and dominant negative (DNE) effects. We aimed to determine if there were differences in somatic TP53 mutation types by patient ancestry or TNBC status. METHODS: We identified breast cancer datasets with somatic TP53 mutation data, ancestry, age, and hormone receptor status. Mutations were classified for functional impact using published data and type of mutation. We assessed differences using Fisher's exact test. RESULTS: From 96 breast cancer studies, we identified 2964 women with somatic TP53 mutations: 715 (24.1%) Asian, 258 (8.7%) AA, 1931 (65.2%) NHW, and 60 (2%) Latina. The distribution of TP53 mutation type was similar by ancestry. However, 35.8% of tumors from NHW individuals had GOF mutations compared to 29% from AA individuals (p = 0.04). Mutations with DNE activity were positively associated with TNBC (OR 1.37, p = 0.03) and estrogen receptor (ER) negative status (OR 1.38; p = 0.005). CONCLUSIONS: Somatic TP53 mutation types did not differ by ancestry overall, but GOF mutations were more common in NHW women than AA women. ER-negative and TNBC tumors are less likely to have DNE+ TP53 mutations which could reflect biological processes. Larger cohorts and functional studies are needed to further elucidate these findings.

The risks of breast and ovarian cancer associated with the Ashkenazi Jewish founder allele BRCA2 6174delT.

Approximately 1% of the Ashkenazi Jewish population carries the BRCA2 6174delT (c.5946del) pathogenic variant. It is important to have accurate knowledge of the risks of breast and ovarian cancer associated with this specific variant so that women may be counseled accordingly. In this prospective study, we estimated the risks of breast and ovarian cancer associated with the 6174delT variant compared with the risks for other pathogenic variants in the BRCA2 gene. The annual risk for developing breast cancer was significantly lower in 246 women who carried the 6174delT variant compared with 721 non-Jewish women who carried a variant at any other locus in BRCA2 (1.2% per year vs. 2.4% per year, p = 0.003). We estimated the cumulative risk of breast cancer from age 30 to 70 to be 39% for carriers of the BRCA2 6174delT variant and 61% for carriers of other BRCA2 variants. The annual risk for ovarian or fallopian tube cancer was 0.51% per year for the 233 women who carried the 6174delT variant compared to 0.22% per year for the 1128 carriers of other BRCA2 variants; the difference was not significant. Lower risks for breast cancer associated with 6174delT may not impact screening and prevention choices, however, the discussion should be based on accurate risk assessment.

Contraceptive use and the risk of ovarian cancer among women with a BRCA1 or BRCA2 mutation.

Background BRCA1 and BRCA2 (BRCA) mutation carriers face a high lifetime risk of developing ovarian cancer. Oral contraceptives are protective in this population; however, the impact of other types of contraception (e.g. intrauterine devices, implants, injections) is unknown. We undertook a matched case-control study to evaluate the relationship between type of contraception and risk of ovarian cancer among women with BRCA mutations. Methods A total of 1733 matched pairs were included in this analysis. Women were matched according to year of birth, date of study entry, country of residence, BRCA mutation type and history of breast cancer. Detailed information on hormonal, reproductive and lifestyle exposures were collected from a routinely administered questionnaire. Conditional logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI) associated with each contraceptive exposure. Results Ever use of any contraceptive was significantly associated with reduced risk of ovarian cancer (OR = 0.62; 95% CI 0.52-0.75; P < 0.0001), which was driven by significant inverse associations with oral contraceptives (OR = 0.66; 95% CI 0.54-0.79; P < 0.0001) and contraceptive implants (OR = 0.30; 95% CI 0.12-0.73; P = 0.008). We observed a similar effect with use of injections (OR = 0.37; 95% CI 0.10-1.38; P = 0.14), but this did not achieve significance. No significant associations were observed between patterns of intrauterine device use and risk of ovarian cancer. Conclusions These findings support a protective effect of oral contraceptives and implants on risk of ovarian cancer among women with BRCA mutations. The possible protective effect of injections requires further evaluation.

Cancer health disparities in racial/ethnic minorities in the United States.

There are well-established disparities in cancer incidence and outcomes by race/ethnicity that result from the interplay between structural, socioeconomic, socio-environmental, behavioural and biological factors. However, large research studies designed to investigate factors contributing to cancer aetiology and progression have mainly focused on populations of European origin. The limitations in clinicopathological and genetic data, as well as the reduced availability of biospecimens from diverse populations, contribute to the knowledge gap and have the potential to widen cancer health disparities. In this review, we summarise reported disparities and associated factors in the United States of America (USA) for the most common cancers (breast, prostate, lung and colon), and for a subset of other cancers that highlight the complexity of disparities (gastric, liver, pancreas and leukaemia). We focus on populations commonly identified and referred to as racial/ethnic minorities in the USA-African Americans/Blacks, American Indians and Alaska Natives, Asians, Native Hawaiians/other Pacific Islanders and Hispanics/Latinos. We conclude that even though substantial progress has been made in understanding the factors underlying cancer health disparities, marked inequities persist. Additional efforts are needed to include participants from diverse populations in the research of cancer aetiology, biology and treatment. Furthermore, to eliminate cancer health disparities, it will be necessary to facilitate access to, and utilisation of, health services to all individuals, and to address structural inequities, including racism, that disproportionally affect racial/ethnic minorities in the USA.

Breast cancer risk after age 60 among BRCA1 and BRCA2 mutation carriers.

PURPOSE: It is not known whether the risk of breast cancer among BRCA1 and BRCA2 mutation carriers after age 60 is high enough to justify intensive screening or prophylactic surgery. Thus, we conducted a prospective analysis of breast cancer risk in BRCA1 and BRCA2 mutation carriers from age 60 until age 80. METHODS: Subjects had no history of cancer and both breasts intact at age 60 (n = 699). Women were followed until a breast cancer diagnosis, prophylactic bilateral mastectomy or death. We calculated the annual cancer rate and cumulative incidence of breast cancer (invasive and in situ) from age 60 to age 80. We assessed the associations between hormone replacement therapy, family history of breast cancer and bilateral oophorectomy and breast cancer risk. RESULTS: Over a mean follow-up of 7.9 years, 61 invasive and 20 in situ breast cancers were diagnosed in the cohort. The mean annual rate of invasive breast cancer was 1.8% for BRCA1 mutation carriers and 1.7% for BRCA2 mutation carriers. The cumulative risk of invasive breast cancer from age 60 to 80 was 20.1% for women with a BRCA1 mutation and was 17.3% for women with a BRCA2 mutation. Hormone replacement therapy, family history and oophorectomy were not associated with breast cancer risk. CONCLUSIONS: Findings from this large prospective study indicate that the risk of developing breast cancer remains high after age 60 in both BRCA1 and BRCA2 mutation carriers. These findings warrant further evaluation of the role of breast cancer screening in older mutation carriers.

Breastfeeding and the risk of epithelial ovarian cancer among women with a BRCA1 or BRCA2 mutation.

OBJECTIVE: BRCA mutation carriers face a high lifetime risk of developing ovarian cancer. The strong inverse association between breastfeeding and the risk of ovarian cancer is established in the general population but is less well studied among women with a germline BRCA1 or BRCA2 mutation. METHOD: Thus, we conducted a matched case-control analysis to evaluate the association between breastfeeding history and the risk of developing ovarian cancer. After matching for year of birth, country of residence, BRCA gene and personal history of breast cancer, a total of 1650 cases and 2702 controls were included in the analysis. Conditional logistic regression was used to estimate the odds ratio (OR) and 95% confidence intervals (CI) associated with various breastfeeding exposures. RESULTS: A history of ever-breastfeeding was associated with a 23% reduction in risk (OR = 0.77; 95%CI 0.66-0.90; P = 0.001). The protective effect increased with breastfeeding from one month to seven months after which the association was relatively stable. Compared to women who never breastfed, breastfeeding for seven or more months was associated with a 32% reduction in risk (OR = 0.68; 95%CI 0.57-0.81; P < 0.0001) and did not vary by BRCA gene or age at diagnosis. The combination of breastfeeding and oral contraceptive use was strongly protective (0.47; 95%CI 0.37-0.58; P < 0.0001). CONCLUSIONS: These findings support a protective effect of breastfeeding for at least seven months among women with a BRCA1 or BRCA2 mutation, that is independent of oral contraceptive use.

Urinary cadmium and timing of menarche and pubertal development in girls.

BACKGROUND: Cadmium (Cd) is a developmental toxicant that is released into the environment during industrial processes. Previous animal studies suggest that Cd may impact the onset of puberty. OBJECTIVES: To determine whether Cd exposure, measured as urinary Cd concentration, was associated with ages at menarche and pubertal development. METHODS: A cohort of 211 girls, ages 10-13 years at baseline, was followed for up to two years. Girls completed an interview and self-assessment of Tanner stages of breast development and pubic hair growth. They were followed monthly until menarche. Urinary Cd concentrations were measured in overnight urine specimens. Multivariable Cox regression was used to evaluate the association between urinary Cd and age at menarche and cumulative logit regression was used to evaluate the associations between urinary Cd and breast development and pubic hair growth. RESULTS: The baseline geometric mean creatinine-adjusted Cd concentration was 0.22 µg/g creatinine (geometric standard deviation = 1.6) and decreased with increasing age (p-trend = 0.04). Cd levels were higher among Asian than White girls or girls of other/mixed race/ethnicity (p = 0.04). In multivariable analyses, girls with urinary Cd ≥ 0.4 µg/L were less likely to have attained menarche than girls with urinary Cd < 0.2 µg/L (hazard ratio = 0.42; 95% confidence interval, 0.23-0.78). Urinary Cd was negatively associated with pubic hair growth (p-trend = 0.01) but not with breast development (p-trend = 0.72) at baseline. CONCLUSIONS: These findings suggest that a higher Cd body burden may delay some aspects of pubertal development among girls.

Long-term outcomes following a diagnosis of ovarian cancer at the time of preventive oophorectomy among BRCA1 and BRCA2 mutation carriers.

INTRODUCTION: Preventive bilateral salpingo-oophorectomy is the most effective means of reducing the risk of ovarian cancer among women with an inherited BRCA1 or BRCA2 mutation. Some women are diagnosed with an invasive cancer (ovarian or fallopian tube) at the time of preventive surgery, referred to as an 'occult' cancer. The survival experience of these women is not known. METHODS: We estimated the 10-year survival for 52 BRCA mutation carriers diagnosed with an occult ovarian or fallopian tube cancer at the time of preventive bilateral salpingo-oophorectomy. RESULTS: The mean age at diagnosis was 51.6 (range 33-69) years. All were serous cancers (although 14 were missing information on histologic subtype). Of the 20 cases with information available on stage at diagnosis, 10 were stage I, 1 was stage II, and 9 were stage III (n=32 missing). After a mean of 6.8 years, 12 women died (23%). The 10-year all-cause survival was 74%. CONCLUSION: Although based on only 52 cases, these findings suggest a more favorable prognosis for BRCA mutation carriers diagnosed with an occult rather than incident disease.

Assessing the performance of in silico methods for predicting the pathogenicity of variants in the gene CHEK2, among Hispanic females with breast cancer.

The availability of disease-specific genomic data is critical for developing new computational methods that predict the pathogenicity of human variants and advance the field of precision medicine. However, the lack of gold standards to properly train and benchmark such methods is one of the greatest challenges in the field. In response to this challenge, the scientific community is invited to participate in the Critical Assessment for Genome Interpretation (CAGI), where unpublished disease variants are available for classification by in silico methods. As part of the CAGI-5 challenge, we evaluated the performance of 18 submissions and three additional methods in predicting the pathogenicity of single nucleotide variants (SNVs) in checkpoint kinase 2 (CHEK2) for cases of breast cancer in Hispanic females. As part of the assessment, the efficacy of the analysis method and the setup of the challenge were also considered. The results indicated that though the challenge could benefit from additional participant data, the combined generalized linear model analysis and odds of pathogenicity analysis provided a framework to evaluate the methods submitted for SNV pathogenicity identification and for comparison to other available methods. The outcome of this challenge and the approaches used can help guide further advancements in identifying SNV-disease relationships.

BRCA1 and BRCA2 pathogenic sequence variants in women of African origin or ancestry.

BRCA1 and BRCA2 (BRCA1/2) pathogenic sequence variants (PSVs) confer elevated risks of multiple cancers. However, most BRCA1/2 PSVs reports focus on European ancestry individuals. Knowledge of the PSV distribution in African descent individuals is poorly understood. We undertook a systematic review of the published literature and publicly available databases reporting BRCA1/2 PSVs also accessed the Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA) database to identify African or African descent individuals. Using these data, we inferred which of the BRCA PSVs were likely to be of African continental origin. Of the 43,817 BRCA1/2 PSV carriers in the CIMBA database, 469 (1%) were of African descent. Additional African descent individuals were identified in public databases (n = 291) and the literature (n = 601). We identified 164 unique BRCA1 and 173 unique BRCA2 PSVs in individuals of African ancestry. Of these, 83 BRCA1 and 91 BRCA2 PSVs are of likely or possible African origin. We observed numerous differences in the distribution of PSV type and function in African origin versus non-African origin PSVs. Research in populations of African ancestry with BRCA1/2 PSVs is needed to provide the information needed for clinical management and decision-making in African descent individuals worldwide.

Environmental exposures during windows of susceptibility for breast cancer: a framework for prevention research.

BACKGROUND: The long time from exposure to potentially harmful chemicals until breast cancer occurrence poses challenges for designing etiologic studies and for implementing successful prevention programs. Growing evidence from animal and human studies indicates that distinct time periods of heightened susceptibility to endocrine disruptors exist throughout the life course. The influence of environmental chemicals on breast cancer risk may be greater during several windows of susceptibility (WOS) in a woman's life, including prenatal development, puberty, pregnancy, and the menopausal transition. These time windows are considered as specific periods of susceptibility for breast cancer because significant structural and functional changes occur in the mammary gland, as well as alterations in the mammary micro-environment and hormone signaling that may influence risk. Breast cancer research focused on these breast cancer WOS will accelerate understanding of disease etiology and prevention. MAIN TEXT: Despite the plausible heightened mechanistic influences of environmental chemicals on breast cancer risk during time periods of change in the mammary gland's structure and function, most human studies of environmental chemicals are not focused on specific WOS. This article reviews studies conducted over the past few decades that have specifically addressed the effect of environmental chemicals and metals on breast cancer risk during at least one of these WOS. In addition to summarizing the broader evidence-base specific to WOS, we include discussion of the NIH-funded Breast Cancer and the Environment Research Program (BCERP) which included population-based and basic science research focused on specific WOS to evaluate associations between breast cancer risk and particular classes of endocrine-disrupting chemicals-including polycyclic aromatic hydrocarbons, perfluorinated compounds, polybrominated diphenyl ethers, and phenols-and metals. We outline ways in which ongoing transdisciplinary BCERP projects incorporate animal research and human epidemiologic studies in close partnership with community organizations and communication scientists to identify research priorities and effectively translate evidence-based findings to the public and policy makers. CONCLUSIONS: An integrative model of breast cancer research is needed to determine the impact and mechanisms of action of endocrine disruptors at different WOS. By focusing on environmental chemical exposure during specific WOS, scientists and their community partners may identify when prevention efforts are likely to be most effective.

Identification of novel common breast cancer risk variants at the 6q25 locus among Latinas.

BACKGROUND: Breast cancer is a partially heritable trait and genome-wide association studies (GWAS) have identified over 180 common genetic variants associated with breast cancer. We have previously performed breast cancer GWAS in Latinas and identified a strongly protective single nucleotide polymorphism (SNP) at 6q25, with the protective minor allele originating from indigenous American ancestry. Here we report on fine mapping of the 6q25 locus in an expanded sample of Latinas. METHODS: We performed GWAS in 2385 cases and 6416 controls who were either US Latinas or Mexican women. We replicated the top SNPs in 2412 cases and 1620 controls of US Latina, Mexican, and Colombian women. In addition, we validated the top novel variants in studies of African, Asian and European ancestry. In each dataset we used logistic regression models to test the association between SNPs and breast cancer risk and corrected for genetic ancestry using either principal components or genetic ancestry inferred from ancestry informative markers using a model-based approach. RESULTS: We identified a novel set of SNPs at the 6q25 locus associated with genome-wide levels of significance (p = 3.3 × 10- 8 - 6.0 × 10- 9) not in linkage disequilibrium (LD) with variants previously reported at this locus. These SNPs were in high LD (r2 > 0.9) with each other, with the top SNP, rs3778609, associated with breast cancer with an odds ratio (OR) and 95% confidence interval (95% CI) of 0.76 (0.70-0.84). In a replication in women of Latin American origin, we also observed a consistent effect (OR 0.88; 95% CI 0.78-0.99; p = 0.037). We also performed a meta-analysis of these SNPs in East Asians, African ancestry and European ancestry populations and also observed a consistent effect (rs3778609, OR 0.95; 95% CI 0.91-0.97; p = 0.0017). CONCLUSION: Our study adds to evidence about the importance of the 6q25 locus for breast cancer susceptibility. Our finding also highlights the utility of performing additional searches for genetic variants for breast cancer in non-European populations.

Pathogenic and likely pathogenic variants in PALB2, CHEK2, and other known breast cancer susceptibility genes among 1054 BRCA-negative Hispanics with breast cancer.

BACKGROUND: Breast cancer (BC) is the most common cancer and related cause of mortality among Hispanics, yet susceptibility has been understudied. BRCA1 and BRCA2 (BRCA) mutations explain less than one-half of hereditary BC, and the proportion associated with other BC susceptibility genes is unknown. METHODS: Germline DNA from 1054 BRCA-mutation-negative Hispanic women with hereditary BC (BC diagnosed at age <51 years, bilateral BC, breast and ovarian cancer, or BC diagnosed at ages 51-70 years with ≥2 first-degree or second-degree relatives who had BC diagnosed at age <70 years), 312 local controls, and 887 multiethnic cohort controls was sequenced and analyzed for 12 known and suspected, high-penetrance and moderate-penetrance cancer susceptibility genes (ataxia telangiectasia mutated [ATM], breast cancer 1 interacting protein C-terminal helicase 1 [BRIP1], cadherin 1 [CDH1], checkpoint kinase 2 [CHEK2], nibrin [NBN], neurofibromatosis type 1 [NF1], partner and localizer of BRCA2 [PALB2], phosphatase and tensin homolog [PTEN], RAD51 paralog 3 [RAD51C], RAD51D, serine/threonine kinase 11 [STK11], and TP53). RESULTS: Forty-nine (4.6%) pathogenic or likely pathogenic variants (PVs) in 47 of 1054 participants (4.5%), including 21 truncating frameshift, 20 missense, 5 nonsense, and 4 splice variants, were identified in CHEK2 (n = 20), PALB2 (n = 18), ATM (n = 5), TP53 (n = 3), BRIP1 (n = 2), and CDH1 and NF1 (both n = 1) and none were identified in NBN, PTEN, STK11, RAD51C, or RAD51D. Nine participants carried the PALB2 c.2167_2168del PV (0.85%), and 14 carried the CHEK2 c.707T>C PV (1.32%). CONCLUSIONS: Of 1054 BRCA-negative, high-risk Hispanic women, 4.5% carried a PV in a cancer susceptibility gene, increasing understanding of hereditary BC in this population. Recurrent PVs in PALB2 and CHEK2 represented 47% (23 of 49) of the total, suggesting a founder effect. Accurate classification of variants was enabled by carefully controlling for ancestry and the increased identification of at-risk Hispanics for screening and prevention.