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Objective: Whether or not women who harbor a germline pathogenic variant (‘mutation’) in the BRCA1 or BRCA2 genes are at elevated risk of developing endometrial cancer is yet to be determined. Methods: We conducted a prospective analysis of 4959 BRCA mutation carriers with no prior history of cancer (except for breast or melanoma) and an intact uterus. Results: After a mean of 6.7 years of follow-up there were 38 incident cases of endometrial cancer diagnosed; 30 among BRCA1 carriers and eight among BRCA2 carriers. The mean age at diagnosis was 58.4 years (range 46.8–76.1). The majority were of the endometrioid subtype (n = 16), followed by mixed endometroid and serous (n = 4), serous (n = 3) or clear cell (n = 1) (missing = 13). The cumulative incidence from age 40 to age 70 was 3.4% for BRCA1 carriers and was 1.6% for BRCA2 mutation carriers. Prior tamoxifen use was associated with a significant two–fold increased risk (HR = 2.24; 95% CI 1.10–4.55). There was no significant association between exogenous hormone use, oophorectomy, smoking or BMI at age 40 and risk (P ≥ 0.32). Conclusions: Compared to the general population, we observed higher rates of endometrial cancer among young BRCA1 mutation carriers; however, lifetime risks were similar. Women with prior tamoxifen exposure were at a significantly increased risk. These findings were based. on a small number of incident cases and require confirmation with additional follow-up of our aging cohort.

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.

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.

IMPORTANCE Preventive 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. OBJECTIVE To evaluate the association between bilateral oophorectomy and all-cause mortality among women with a BRCA1 or BRCA2 sequence variation. DESIGN, SETTING, AND PARTICIPANTS In this international, longitudinal cohort study ofwomen 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. EXPOSURES Self-reported bilateral oophorectomy (with or without salpingectomy). MAIN OUTCOMES AND MEASURES All-cause mortality, breast cancer-specific mortality, and ovarian cancer-specific mortality. RESULTS There 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 < .001). The age-adjusted HR was 0.28 (95% CI, 0.20-0.38; P < .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 estima

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 modelingwas 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

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.

Background: BRCA1 and BRCA2 gene mutations are responsible for 5% of breast cancer (BC) and 10–15% of ovarian cancer (EOC). The presence of a germline mutation and therefore the identification of subjects at high risk of developing cancer should ideally precede the onset of the disease, so that appropriate surveillance and risk-reducing treatments can be proposed. In this study, we revisited the family history (FH) of women who tested positive for BRCA mutations after being diagnosed with BC or EOC. Methods: The National Comprehensive Cancer Network (NCCN) Clinical Practice Guidelines in Oncology (NCCN Guidelines®), and the Italian Association of Medical Oncology (AIOM) guidelines were applied to the FH of 157 women who were referred to San Gerardo Hospital for genetic counseling. Results: Almost 85% of women had an FH of BRCA-related cancer. 63.7% and 52.2% of women could have undergone genetic testing according to NCCN and AIOM testing criteria (p <.05) before tumor diagnosis. An FH of EOC was the most frequent NCCN criterion, followed by BC diagnosed <45 years old. Sixty-five percent of deceased women could have undergone genetic testing before developing cancer. Conclusions: FH is a powerful tool to identify high-risk individuals eligible for genetic counseling and testing. Testing of healthy individuals should be considered when an appropriately affected family member is unavailable for testing.

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.

Item does not contain fulltext, BACKGROUND: The role of ovulation in epithelial ovarian cancer (EOC) is supported by the consistent protective effects of parity and oral contraceptive use. Whether these factors protect through anovulation alone remains unclear. We explored the association between lifetime ovulatory years (LOY) and EOC. METHODS: LOY was calculated using 12 algorithms. Odds ratios (ORs) and 95% confidence intervals (CIs) estimated the association between LOY or LOY components and EOC among 26 204 control participants and 21 267 case patients from 25 studies. To assess whether LOY components act through ovulation suppression alone, we compared beta coefficients obtained from regression models with expected estimates assuming 1 year of ovulation suppression has the same effect regardless of source. RESULTS: LOY was associated with increased EOC risk (OR per year increase = 1.014, 95% CI = 1.009 to 1.020 to OR per year increase = 1.044, 95% CI = 1.041 to 1.048). Individual LOY components, except age at menarche, also associated with EOC. The estimated model coefficient for oral contraceptive use and pregnancies were 4.45 times and 12- to 15-fold greater than expected, respectively. LOY was associated with high-grade serous, low-grade serous, endometrioid, and clear cell histotypes (ORs per year increase = 1.054, 1.040, 1.065, and 1.098, respectively) but not mucinous tumors. Estimated coefficients of LOY components were close to expected estimates for high-grade serous but larger than expected for low-grade serous, endometrioid, and clear cell histotypes. CONCLUSIONS: LOY is positively associated with nonmucinous EOC. Differences between estimated and expected model coefficients for LOY components suggest factors beyond ovulation underlie the associations between LOY components and EOC in general and for non-HGSOC.

BACKGROUND: The role of ovulation in epithelial ovarian cancer (EOC) is supported by the consistent protective effects of parity and oral contraceptive use. Whether these factors protect through anovulation alone remains unclear. We explored the association between lifetime ovulatory years (LOY) and EOC. METHODS: LOY was calculated using 12 algorithms. Odds ratios (ORs) and 95% confidence intervals (CIs) estimated the association between LOY or LOY components and EOC among 26 204 control participants and 21 267 case patients from 25 studies. To assess whether LOY components act through ovulation suppression alone, we compared beta coefficients obtained from regression models with expected estimates assuming 1 year of ovulation suppression has the same effect regardless of source. RESULTS: LOY was associated with increased EOC risk (OR per year increase = 1.014, 95% CI = 1.009 to 1.020 to OR per year increase = 1.044, 95% CI = 1.041 to 1.048). Individual LOY components, except age at menarche, also associated with EOC. The estimated model coefficient for oral contraceptive use and pregnancies were 4.45 times and 12- to 15-fold greater than expected, respectively. LOY was associated with high-grade serous, low-grade serous, endometrioid, and clear cell histotypes (ORs per year increase = 1.054, 1.040, 1.065, and 1.098, respectively) but not mucinous tumors. Estimated coefficients of LOY components were close to expected estimates for high-grade serous but larger than expected for low-grade serous, endometrioid, and clear cell histotypes. CONCLUSIONS: LOY is positively associated with nonmucinous EOC. Differences between estimated and expected model coefficients for LOY components suggest factors beyond ovulation underlie the associations between LOY components and EOC in general and for non-HGSOC.

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.

Contains fulltext : 299856.pdf (Publisher’s version ) (Open Access), Women at high inherited risk of ovarian cancer are offered risk-reducing salpingo-oophorectomy (RRSO) from age 35 to 45 years. Although potentially life-saving, RRSO may induce symptoms that negatively affect quality of life and impair long-term health. Clinical care following RRSO is often suboptimal. This scoping review describes how RRSO affects short- and long-term health and provides evidence-based international consensus recommendations for care from preoperative counselling to long-term disease prevention. This includes the efficacy and safety of hormonal and non-hormonal treatments for vasomotor symptoms, sleep disturbance and sexual dysfunction and effective approaches to prevent bone and cardiovascular disease., 01 november 2023

Women at high inherited risk of ovarian cancer are offered risk-reducing salpingo-oophorectomy (RRSO) from age 35 to 45 years. Although potentially life-saving, RRSO may induce symptoms that negatively affect quality of life and impair long-term health. Clinical care following RRSO is often suboptimal. This scoping review describes how RRSO affects short- and long-term health and provides evidence-based international consensus recommendations for care from preoperative counselling to long-term disease prevention. This includes the efficacy and safety of hormonal and non-hormonal treatments for vasomotor symptoms, sleep disturbance and sexual dysfunction and effective approaches to prevent bone and cardiovascular disease.

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.

OBJECTIVE: To describe tubal histopathological abnormalities in women with germline BRCA1/2 mutations and in controls. METHODS: Consecutive women with BRCA1/2 mutations undergoing bilateral salpingo-oophorectomy between 2010 and 2020 in two centers (San Gerardo Hospital, Monza and San Matteo Hospital, Pavia) were considered in this analysis and compared with controls who had the same surgical procedure for benign conditions. Frequency of p53 signature, serous tubal intraepithelial carcinoma, and high-grade serous ovarian cancer were compared between the two groups. RESULTS: A total of 194 women with pathogenic BRCA1/2 mutations underwent prophylactic salpingo-oophorectomy. Of these, 138 women (71%) had a completely negative histological examination, while in 56 (29%) patients an ovarian or tubal alteration was reported. Among controls, 84% of patients had a p53wt signature, while 16% had a p53 signature. There was no difference in the frequency of a p53 signature between cases and controls; however, women with BRCA1/2 mutations were more likely to have pre-malignant or invasive alterations of tubal or ovarian epithelium (p=0.015). Among mutation carriers, older age both at genetic testing and at surgery was associated with an increased risk of having malignancies (OR=1.07, p=0.006 and OR=1.08, p=0.004, respectively). The risk of malignancy seems to be increased in patients with a familial history of high-grade serous ovarian cancer. Previous therapy with tamoxifen was significantly more frequent in patients with malignant lesions (40.0% vs 21.3%, p=0.006). CONCLUSION: We found that a p53 signature is a frequent finding both in BRCA1/2 mutation carriers and in controls, while pre-invasive and invasive lesions are more frequent in BRCA1/2 mutation carriers. Genetic and clinical characteristics are likely to affect the progression to malignancy.

Background: The lack of consensus on whether bilateral oophorectomy impacts risk of developing breast cancer among BRCA1 mutation carriers might be attributed to various biases, specifically, cancer-induced testing bias due to inclusion of prevalent cases. We conducted two complementary matched case-control analyses to evaluate the association of oophorectomy and BRCA1 breast cancer. Methods: A research questionnaire was administered every two years to collect information on exposures and disease. In the first analysis, we limited the study to prevalent breast cancer cases (diagnosed prior to study entry; n = 2,962) who were matched to controls on year of birth and country of residence (n=4,358). In the second approach, we limited to 330 incident cases (diagnosed in the follow-up period) and 1,548 matched controls. Conditional logistic regression was used to estimate the adjusted odds ratios (OR) and 95% confidence intervals (CI) of invasive breast cancer. Results: In the first approach, there was a significant inverse association between oophorectomy and the risk of developing breast cancer [OR = 0.43; 95% confidence interval (CI), 0.34- 0.55; P < 00001]. In the second approach, there was no association between oophorectomy and risk (OR = 1.21; 95% CI, 0.87-1.70; P = 0.26). Conclusions: The inclusion of women with a personal history of breast cancer prior to ascertainment likely impacts upon the association of oophorectomy and BRCA1 breast cancer risk. Impact: Oophorectomy is unlikely a determinant of breast cancer risk in BRCA1 mutation carriers but should be offered at age 35 to reduce the risk of ovarian and fallopian tube cancer.

Background: Weight gain and other anthropometric measures on the risk of ovarian cancer for women with BRCA mutations are not known. We conducted a prospective analysis of weight change since age 18, height, body mass index (BMI) at age 18, and current BMI and the risk of developing ovarian cancer among BRCA1 and BRCA2 mutation carriers. Methods: In this prospective cohort study, height, weight, and weight at age 18 were collected at study enrollment. Weight was updated biennially. Cox proportional hazards models were used to estimate the hazard ratio (HR) and 95% confidence intervals (CI) for ovarian cancer. Results: This study followed 4,340 women prospectively. There were 121 incident cases of ovarian cancer. Weight gain of more than 20 kg since age 18 was associated with a 2-fold increased risk of ovarian cancer, compared with women who maintained a stable weight (HR, 2.00; 95% CI, 1.13-3.54; P 1⁄4 0.02). Current BMI of 26.5 kg/m2 or greater was associated with an increased risk of ovarian cancer in BRCA1 mutation carriers, compared with those with a BMI less than 20.8 kg/m2 (Q4 vs. Q1 HR, 2.13; 95% CI, 1.04-4.36; P 1⁄4 0.04). There were no significant associations between height or BMI at age 18 and risk of ovarian cancer. Conclusions: Adult weight gain is a risk factor for ovarian cancer in women with a BRCA1 or BRCA2 mutation. Impact: These findings emphasize the importance of maintaining a healthy body weight throughout adulthood in women at high risk for ovarian cancer.

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.

Purpose: Following a diagnosis of breast cancer, BRCA mutation carriers face an increased risk of developing a second (contralateral) cancer in the unaffected breast. It is important to identify predictors of contralateral cancer in order to make informed decisions about bilateral mastectomy. The impact of bilateral salpingo-oophorectomy (i.e., oophorectomy) on the risk of developing contralateral breast cancer is unclear. Thus, we conducted a prospective study of the relationship between oophorectomy and the risk of contralateral breast cancer in 1781 BRCA1 and 503 BRCA2 mutation carriers with breast cancer. Methods: Women were followed from the date of diagnosis of their first breast cancer until the date of diagnosis of a contralateral breast cancer, bilateral mastectomy, date of death, or date of last follow-up. Cox proportional hazards regression was used to estimate the hazard ratio (HR) and 95% confidence interval (CI) of contralateral breast cancer associated with oophorectomy. Oophorectomy was included as a time-dependent covariate. We performed a left-censored analysis for those women who reported a primary breast cancer prior to study entry (i.e., from completion of baseline questionnaire). Results: After an average of 9.8 years of follow-up, there were 179 (7.8%) contralateral breast cancers diagnosed. Oophorectomy was not associated with the risk of developing a second breast cancer (HR 0.92; 95% CI 0.68–1.25). The relationship did not vary by BRCA mutation type or by age at diagnosis of the first breast cancer. There was some evidence for a decreased risk of contralateral breast cancer among women with an ER-positive primary breast cancer, but this was based on a small number of events (n = 240). Conclusion: Overall, our findings suggest that oophorectomy has little impact on the risk of contralateral breast cancer