Citations

PURPOSE BRCA carriers face high risks of developing both breast and ovarian/fallopian tube cancers (hereafter referred to as ovarian ). Among BRCA carriers with ovarian cancer, it is not clear whether the risk of breast cancer is sufficiently high that risk-reducing mastectomy should be offered. This study aimed to assess the risk of breast cancer BRCA carriers after a diagnosis of ovarian cancer. METHODS We included women with a pathogenic/likely pathogenic variant in BRCA1 or BRCA2 , a diagnosis of ovarian cancer, and no other cancer history and no risk-reducing bilateral mastectomy. Women were followed for incident breast cancer from the date of ovarian cancer diagnosis or the date of baseline questionnaire, whichever came last. The 5-, 10-, and 15-year cumulative risks of breast cancer were compared for women with ovarian cancer and an age-matched set of control women without ovarian cancer. RESULTS A total of 960 participants with ovarian cancer were identified (814 BRCA1 and 146 BRCA2 carriers). After a mean follow-up of 4.9 years, 41 women (4.3%) developed breast cancer, at a mean age at diagnosis of 57.5 years (range, 39-74). Actuarial cumulative breast cancer risks after ovarian cancer were 4.4%, 8.9%, and 11.5% at 5, 10, and 15 years, respectively. Only three breast cancer–related deaths occurred. Among 741 age-matched BRCA carriers without ovarian cancer, actuarial cumulative risks of breast cancer were 20.9%, 38.6%, and 47.2% at 5, 10, and 15 years, respectively. The hazard ratio for breast cancer, after an ovarian cancer diagnosis, compared with no ovarian cancer, was 0.18 ([95% CI, 0.12 to 0.27]; P < .0001). CONCLUSION After ovarian cancer, BRCA carriers have a relatively low risk of breast cancer. Risk-reducing mastectomy should not be recommended routinely, but might be considered for long-term survivors. Magnetic resonance imaging surveillance and/or mammography is a realistic alternative.

Abstract Background: Women with a pathogenic variant in the BRCA1 or BRCA2 gene (carriers) are at a high risk of developing ovarian cancer and recommended to undergo bilateral salpingo-oophorectomy at an early age resulting in surgical menopause. Menopausal hormone therapy (MHT) is the most effective way to mitigate the adverse outcomes of early menopause; however, the safety of MHT on breast cancer risk in this population has not been established. Methods: We conducted a prospective matched analysis of MHT use following menopause (predominantly surgical) and breast cancer risk in BRCA carriers using a matched prospective analysis to emulate a randomized clinical trial. Women without a history of any cancer or bilateral mastectomy and who were enrolled in a longitudinal study with detailed data collection were eligible for inclusion. Women who initiated MHT (exposed) after menopause were matched one-to-one to women who had not initiated MHT (unexposed) by gene, year of birth, and age at menopause, resulting in 676 matched pairs. Cox proportional hazards regression to estimate the hazard ratios (HR) and 95%CIs (CI) of incident breast cancer associated with MHT use. Results: After a mean follow-up of 5.6 years from the date of first MHT use in the exposed woman, there were 87 incident breast cancer cases in the exposed group (12·9%) and 128 cases in the unexposed group (18·9%) (P = 0·002). Compared to their unexposed match, women who used estrogen (E) experienced a significant decrease in the risk of breast cancer (HR = 0·37; 95%: CI 0·24-0·57). There was no protective (or adverse) effect associated with the use of E plus progestogen (E+P) (HR = 0·94; 95%CI 0·54-1·63), with progestogen alone (P) (HR = 1·14; 95%CI: 0·21-6·22) or with tibolone (HR = 0·57; 95%CI: 0·19-1·69). There were no diagnoses of breast cancer in the 43 women who used a CEE + bazedoxifene. Findings were similar for carriers of either gene mutation. Conclusion: To our knowledge, this represents the largest prospective report of MHT use and breast cancer risk in BRCA1 and BRCA2 carriers. Our findings showed no increase in the risk of breast cancer with the use of MHT, irrespective of gene mutation or formulation. These findings provide an evidence-based approach for the management of women at high-risk of breast cancer who are facing the acute and chronic effects of early surgical menopause. The safe use of MHT by BRCA carriers will continue to be an important research topic as formulations continue to evolve. Citation Format: J. Kotsopoulos, M. Seca, G. Jacek, T. Huzarski, P. Møller, R. H. Kim, C. Singer, B. Karlan, A. Aeilts, T. Ramon y Cajal, T. Pal, A. Eisen, L. Bordeleau, W. Foulkes, N. Tung, F. Couch, S. Neuhausen, D. Zakalik, C. Cybulski, O. Olopade, K. Metcalfe, R. Fruscio, P. Sun, J. Lubinski, S. Narod, Hereditary Breast Cancer Clinical Study Group. Menopausal Hormone Therapy and the Risk of Breast Cancer in Women with a Pathogenic Variant in BRCA1 or BRCA2 [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr GS3-01.

Background: Carriers of a pathogenic variant (PV) in BRCA1 face a high risk of breast cancer. This study estimated the risk of developing breast cancer according to mutation type and location. Methods: BRCA1 carriers with no personal history of breast cancer or bilateral mastectomy were included. Detailed information on clinical and family history was collected by questionnaire. Survival analysis was used to estimate 15-year cumulative risk according to PV type and location. Results: A total of 3677 BRCA1 carriers were followed for a mean of 7.2 years (range 0.1–15.0 years); 481 incident breast cancers were documented. Overall, the 15-year cumulative incidence was 25%. Risk estimates varied by exon, ranging from 9% (exon 21) to 19% (exon 12) to 36% (exon 15); however, strata were small. Carriers of four founder mutations common in Eastern Europe (c.5263_5264insC, c.181T > G, c.66_67delAG and c.4034delA) experienced a lower-than-expected cancer risk (15.9–24.4%) compared to other PVs (28.8%) (p = 0.02). Conclusions: Although our data suggests some variability in penetrance based on specific BRCA1 PV, this was based on a large number of founder mutations. Breast cancer management strategies should continue to be based on comprehensive risk assessment.

Abstract Background Women with a pathogenic variant in BRCA1 or BRCA2 are at high risk of developing ovarian cancer, and it is often recommended that they undergo bilateral salpingo-oophorectomy at an early age, resulting in surgical menopause. Menopausal hormone replacement therapy (HRT) is an effective way to mitigate the adverse outcomes of early menopause; however, the safety of menopausal HRT on breast cancer risk in this population has not been established. Methods We conducted a prospective matched analysis of HRT use following menopause and breast cancer risk in BRCA carriers. Women who initiated HRT were matched one-to-one with women who had not initiated menopausal HRT by gene, year of birth, and age at menopause, resulting in 676 matched pairs. Menopausal HRT use collected by questionnaire included formulation and mode of administration. Results After a mean of 5.6 years, there were 87 (12.9%) incident breast cancer cases in the 676 exposed women and 128 (18.9%) cases in the 676 unexposed women (P = .002). Compared with unexposed matched control individuals, women who used estrogen alone experienced a statistically significantly decreased risk of breast cancer (hazard ratio = 0.37, 95% CI = 0.24 to 0.57). No protective or adverse effect was associated with the use of estrogen plus progestogen (hazard ratio = 0.94, 95% CI = 0.54 to 1.63). Conclusions Our findings suggest no substantial increase in the risk of breast cancer in BRCA carriers with the use of HRT and that estrogen alone might be protective.

Background: Endometriosis affects an estimated 10% of reproductive-aged women and is associated with increased ovarian cancer risk. While BRCA1/2 mutations are established risk factors for ovarian cancer, their association with endometriosis remains unclear. This study aimed to characterize the prevalence and clinical features of endometriosis within a large cohort of BRCA mutation carriers. Methods: A descriptive analysis was conducted using data from a multi-center longitudinal cohort of women with pathogenic BRCA variants. Reproductive history and related factors were collected through self-reported questionnaires and compared. Results: Among 16,950 BRCA carriers, the prevalence of endometriosis was 2.4%. Compared to BRCA carriers without endometriosis, those with endometriosis were more likely to carry a BRCA2 mutation, have post-secondary education, and experience earlier menarche. BRCA carriers with endometriosis had a lower ovarian cancer prevalence than those without (10% vs. 15%, p < 0.001). Conclusions: This is the first study of this scale to report the prevalence of endometriosis among BRCA mutation carriers, which was lower than previously reported in the general population. The association between endometriosis and ovarian cancer does not appear to be generalizable to this population. Further prospective studies are warranted to clarify this association among BRCA mutation carriers.

Abstract BRCA-associated homologous recombination deficiency (HRD) is present in ~ 50% of high-grade serous carcinomas (HGSC) and predicts sensitivity to platinum-based therapy. However, there is little understanding of why some patients with BRCA-deficient tumors experience unexpectedly poor outcomes. We profiled 154 tumors, enriched for patients with BRCA-deficient tumors that experienced short overall survival (≤ 3 years, n = 42), using whole-genome, transcriptome, and methylation analyses. All but one BRCA-deficient tumor exceeded an accepted HRD genomic scarring threshold. However, patients with BRCA1-deficient HGSC with a more elevated HRD score survived significantly longer. Patients with BRCA2-deficient HGSC and loss of NF1 survived twice as long as those without NF1 loss, whereas PIK3CA or RAD21 amplification defined BRCA2-deficient HGSC with exceptionally short survival. BRCA1-deficient tumors in short survivors had evidence of immunosuppressive c-kit signaling and EMT. In a large HGSC cohort (n = 1,389) including 282 individuals with pathogenic germline BRCA variants (gBRCApv), the location of the mutation within functional domains stratified clinical outcomes. Notably, residual disease after primary surgery had limited prognostic effect in gBRCApv-carriers compared to non-carriers. Our findings indicate that tumor HR proficiency in the context of therapy response and survival is not a binary property, and highlight genomic and immune modifiers of outcomes in BRCA-deficient HGSC.

Abstract Hereditary tumor predisposition syndromes pose a challenge for early detection and timely treatment of tumors. In von Hippel–Lindau disease, desirable personalized surveillance programs are lacking due to insufficient data on genotype-specific risk profiles of individual mutations. To describe neoplastic risk profiles for carriers of pathogenic and likely pathogenic VHL germline mutations, our observational study recruited 1,350 participants from 40 centers worldwide. 432 different VHL germline mutations were observed, with p.Asn78Ser, p.Arg161Ter, p.Arg161Gln, p.Arg167Gln, p.Arg167Trp and p.Tyr98His being the six most frequent, occurring in a total of 493 carriers (36.5%) and in ≥30 patients each. Age-related penetrance risks for retinal hemangioblastoma, central nervous system hemangioblastoma, renal cell carcinoma, pancreatic neuroendocrine tumors and pheochromocytoma/paraganglioma in carriers of the most frequent VHL mutations were assessed. In addition, the number of organs affected, the frequency of surgery and the outcome are reported. Pairwise comparisons of the age-dependent tumor penetrance of these six mutations showed that 47 out of 90 pairs were significantly different. The most significant associations were found in p.Tyr98His (n = 19), followed by p.Arg161Ter (n = 10). All pairwise comparisons of mutations affecting different codons showed at least one significant (P &lt; 0.05) difference, except for p.Asn78Ser vs p.Arg161Ter. Thus, tumor risk varied by VHL mutation type and location, but did not differ between the truncating mutation p.Arg161Ter and the missense mutation p.Asn78Ser. Our study demonstrates the importance of mutation-specific phenotype prediction. With appropriate validation, the data have important implications for risk assessment and decision making in tumor prevention for carriers of the respective VHL mutations.

Abstract Purpose: The purpose of this study was to evaluate RB1 expression and survival across ovarian carcinoma histotypes and how co-occurrence of BRCA1 or BRCA2 (BRCA) alterations and RB1 loss influences survival in tubo-ovarian high-grade serous carcinoma (HGSC). Experimental Design: RB1 protein expression was classified by immunohistochemistry in ovarian carcinomas of 7,436 patients from the Ovarian Tumor Tissue Analysis consortium. We examined RB1 expression and germline BRCA status in a subset of 1,134 HGSC, and related genotype to overall survival (OS), tumor-infiltrating CD8+ lymphocytes, and transcriptomic subtypes. Using CRISPR-Cas9, we deleted RB1 in HGSC cells with and without BRCA1 alterations to model co-loss with treatment response. We performed whole-genome and transcriptome data analyses on 126 patients with primary HGSC to characterize tumors with concurrent BRCA deficiency and RB1 loss. Results: RB1 loss was associated with longer OS in HGSC but with poorer prognosis in endometrioid ovarian carcinoma. Patients with HGSC harboring both RB1 loss and pathogenic germline BRCA variants had superior OS compared with patients with either alteration alone, and their median OS was three times longer than those without pathogenic BRCA variants and retained RB1 expression (9.3 vs. 3.1 years). Enhanced sensitivity to cisplatin and paclitaxel was seen in BRCA1-altered cells with RB1 knockout. Combined RB1 loss and BRCA deficiency correlated with transcriptional markers of enhanced IFN response, cell-cycle deregulation, and reduced epithelial–mesenchymal transition. CD8+ lymphocytes were most prevalent in BRCA-deficient HGSC with co-loss of RB1. Conclusions: Co-occurrence of RB1 loss and BRCA deficiency was associated with exceptionally long survival in patients with HGSC, potentially due to better treatment response and immune stimulation.

ImportancePreventive bilateral salpingo-oophorectomy is offered to women at high risk of ovarian cancer who carry a pathogenic variant in BRCA1 or BRCA2; however, the association of oophorectomy with all-cause mortality has not been clearly defined.ObjectiveTo evaluate the association between bilateral oophorectomy and all-cause mortality among women with a BRCA1 or BRCA2 sequence variation.Design, Setting, and ParticipantsIn this international, longitudinal cohort study of women with BRCA sequence variations, information on bilateral oophorectomy was obtained via biennial questionnaire. Participants were women with a BRCA1 or BRCA2 sequence variation, no prior history of cancer, and at least 1 follow-up questionnaire completed. Women were followed up from age 35 to 75 years for incident cancers and deaths. Cox proportional hazards regression was used to estimate the hazard ratios (HRs) and 95% CIs for all-cause mortality associated with a bilateral oophorectomy (time dependent). Data analysis was performed from January 1 to June 1, 2023.ExposuresSelf-reported bilateral oophorectomy (with or without salpingectomy).Main Outcomes and MeasuresAll-cause mortality, breast cancer–specific mortality, and ovarian cancer–specific mortality.ResultsThere were 4332 women (mean age, 42.6 years) enrolled in the cohort, of whom 2932 (67.8%) chose to undergo a preventive oophorectomy at a mean (range) age of 45.4 (23.0-77.0) years. After a mean follow-up of 9.0 years, 851 women had developed cancer and 228 had died; 57 died of ovarian or fallopian tube cancer, 58 died of breast cancer, 16 died of peritoneal cancer, and 97 died of other causes. The age-adjusted HR for all-cause mortality associated with oophorectomy was 0.32 (95% CI, 0.24-0.42; P &amp;lt; .001). The age-adjusted HR was 0.28 (95% CI, 0.20-0.38; P &amp;lt; .001) and 0.43 (95% CI, 0.22-0.90; P = .03) for women with BRCA1 and BRCA2 sequence variations, respectively. For women with BRCA1 sequence variations, the estimated cumulative all-cause mortality to age 75 years for women who had an oophorectomy at age 35 years was 25%, compared to 62% for women who did not have an oophorectomy. For women with BRCA2 sequence variations, the estimated cumulative all-cause mortality to age 75 years was 14% for women who had an oophorectomy at age 35 years compared to 28% for women who did not have an oophorectomy.Conclusions and RelevanceIn this cohort study among women with a BRCA1 or BRCA2 sequence variation, oophorectomy was associated with a significant reduction in all-cause mortality.

Importance Magnetic resonance imaging (MRI) surveillance is offered to women with a pathogenic variant in the BRCA1 or BRCA2 gene who face a high lifetime risk of breast cancer. Surveillance with MRI is effective in downstaging breast cancers, but the association of MRI surveillance with mortality risk has not been well defined. Objective To compare breast cancer mortality rates in women with a BRCA1 or BRCA2 sequence variation who entered an MRI surveillance program with those who did not. Design, Setting, and Participants Women with a BRCA1 or BRCA2 sequence variation were identified from 59 participating centers in 11 countries. Participants completed a baseline questionnaire between 1995 and 2015 and a follow-up questionnaire every 2 years to document screening histories, incident cancers, and vital status. Women who had breast cancer, a screening MRI examination, or bilateral mastectomy prior to enrollment were excluded. Participants were followed up from age 30 years (or the date of the baseline questionnaire, whichever was later) until age 75 years, the last follow-up, or death from breast cancer. Data were analyzed from January 1 to July 31, 2023. Exposures Entrance into an MRI surveillance program. Main Outcomes and Measures Cox proportional hazards modeling was used to estimate the hazard ratios (HRs) and 95% CIs for breast cancer mortality associated with MRI surveillance compared with no MRI surveillance using a time-dependent analysis. Results A total of 2488 women (mean [range] age at study entry 41.2 [30-69] years), with a sequence variation in the BRCA1 (n = 2004) or BRCA2 (n = 484) genes were included in the analysis. Of these participants, 1756 (70.6%) had at least 1 screening MRI examination and 732 women (29.4%) did not. After a mean follow-up of 9.2 years, 344 women (13.8%) developed breast cancer and 35 women (1.4%) died of breast cancer. The age-adjusted HRs for breast cancer mortality associated with entering an MRI surveillance program were 0.20 (95% CI, 0.10-0.43; P &amp;lt; .001) for women with BRCA1 sequence variations and 0.87 (95% CI, 0.10-17.25; P = .93) for women with BRCA2 sequence variations. Conclusion and Relevance Results of this cohort study suggest that among women with a BRCA1 sequence variation, MRI surveillance was associated with a significant reduction in breast cancer mortality compared with no MRI surveillance. Further studies of women with BRCA2 sequence variations are needed to ascertain these women obtain the same benefits associated with MRI surveillance.