Evidence-based management options for women at increased breast/ovarian cancer risk.

Recent developments in our ability to predict breast cancer risk necessitates primary care physicians learn to evaluate breast cancer risk and its importance in shaping decisions concerning surveillance and risk reduction measures. This article reviews the current opinion on risk assessment and management of women with an increased risk of breast/ovarian cancer. Management options are given for women at slightly, moderately and highly elevated breast cancer risk, as well as for BRCA1/2 carriers, based on currently available evidence.     

The role of poly adenosine diphosphate ribose polymerase inhibitors in breast and ovarian cancer: current status and future directions

Poly adenosine diphosphate ribose polymerase (PARP) inhibitors have demonstrated single agent activity in the treatment of patients with recurrent BRCA1-mutated and BRCA2-mutated breast and ovarian cancers. They also appear to have a potential role as maintenance therapy following chemotherapy in patients with platinum sensitive recurrent sporadic and BRCA1/2 related high-grade serous ovarian cancers. The concept of BRCAness raises the possibility that PARP inhibitors may be active in selected patients with homologous recombination (HR) DNA repair-deficient tumors, even if they do not harbor a BRCA1/2 germline mutation. Further research will be required to identify the subset of patients with sporadic cancers who may benefit from PARP inhibitor therapy. Precise details on the mechanisms of action, relative potency and anti-cancer effects of different PARP inhibitors remain to be clarified and are being investigated. PARP inhibitors are known to inhibit the base excision repair (BER) pathway but in addition, recent reports indicate that aberrant activation of the error-prone non-homologous end-joining (NHEJ) pathway occurs in HR-deficient cells and that cell death provoked by PARP inhibition is dependent on NHEJ-induced genomic instability. Characterization of the precise molecular mechanisms responsible for PARP inhibitor activity should lead to the identification of predictive biomarkers of response and help identify which patients should be treated with PARP inhibitors. This is a very active field of research and the current status and future directions are reviewed.     

Risk of metachronous breast cancer after BRCA mutation–associated ovarian cancer

BACKGROUND:

This study sought to estimate the risk of breast cancer (BC) after a diagnosis of ovarian cancer (OC) associated with mutation of the BRCA1/2 (breast cancer, early onset) genes (BRCA‐OC).

METHODS:

The Memorial Sloan‐Kettering Cancer Center and the University of Pennsylvania, clinical genetics databases were searched to identify women with BRCA‐OC who participated in genetic testing and follow‐up studies from 1995 to 2009. The primary objective was to determine the risk of developing BC after BRCA‐OC. Overall survival (OS) and BC‐free survival (BCFS) were determined by the Kaplan‐Meier method; patients were censored at the time of last follow‐up.

RESULTS:

A total of 164 patients had BRCA‐OC (115 with BRCA1; 49 with BRCA2). Of these 164 patients, 152 developed OC prior to BRCA testing (median time to testing, 2.4 years [0.01‐55 years]). Median follow‐up from OC for those not developing BC was 5.8 years (0.25‐55.6 years). There were 46 deaths, but none were due to BC. The 5‐ and 10‐year OS were 85% (95% confidence interval [CI] = 0.78, 0.90) and 68% (95% CI = 0.59, 0.76), respectively. There were 18 metachronous BC diagnoses. The 5‐ and 10‐year BCFS were 97% (95% CI = 0.92, 0.99) and 91% (95% CI = 0.82, 0.95), respectively. A subset of 64 women were tested either before or within 12 months of BRCA‐OC. In this pseudo‐incident subset, 5‐ and 10‐ year OS was 71% (95% CI = 0.53, 0.83) and 62% (95% CI = 0.44, 0.75), respectively, and 5‐ and 10‐year BCFS were 100% and 87% (95% CI = 0.56, 0.96), respectively.

CONCLUSIONS:

OS was dominated by OC deaths. Metachronous BC risk was lower than reported for unaffected BRCA mutation carriers. These results support nonsurgical management of BC risk in women with BRCA‐OC. Cancer 2013. © 2012 American Cancer Society.     

Cancer risks in women with 2 breast or ovarian cancers: clues to genetic cancer susceptibility.

Women diagnosed with 2 cancers of the breast and/or ovary are at higher risk of developing subsequent cancers. Using registrations from the Thames Cancer Registry, we quantified the risks at different cancer sites. Increased risks were found for cancers that are part of the BRCA1 and BRCA2 tumour spectrum: oropharyngeal cancer, malignant melanoma of the skin (BRCA2) and colon cancer (BRCA1). We also found significantly increased risks of myeloid leukaemia (probably due to radiotherapy) and of cancer of the corpus uteri (which may be due to hormonal factors).     

Reproductive factors in hereditary breast cancer

Background: An early age at menarche, a short menstrual cycle length, and a high age at first full term pregnancy or nulliparity are known risk factors for breast cancer. These risk factors have previously been reported to differ between breast cancer patients with and without a family history of breast cancer and also between breast cancer patients and controls. Methods: Self-administered questionnaires were filled out by 95 women belonging to 24 families with known BRCA1 mutations, 16 women belonging to nine families with known BRCA2 mutations, and 95 women belonging to 65 families with hereditary breast cancer where no BRCA1 or BRCA2 mutations could be detected. Thirty-nine women were BRCA1 mutation carriers and 56 women were BRCA1 negative, 11 women were BRCA2 carriers and five BRCA2 negative. All women were born between 1905 and 1979. Results: Age at menarche, physiological menstrual cycle length at age 30 or at current age in younger women (when not using oral contraceptives), age at first full term pregnancy, and nulliparity did not significantly differ between BRCA1 mutation carriers and BRCA1 negative women. Too few women were BRCA2 negative to serve as a control group. BRCA2 mutation carriers were therefore compared with BRCA1 negative and BRCA2 negative women. None of the above reproductive factors did significantly differ between BRCA2 mutation carriers and from BRCA1 and BRCA2 families. Women from non-BRCA1/BRCA2 hereditary breast cancer families had a higher age at menarche, but this was no longer significant after adjustment for other factors in a multivariate model. Conclusion: Our results suggest that reproductive risk factors of breast cancer are not related to BRCA1 or BRCA2 carrier status. There was also no indication that these factors differ in carriers of unknown susceptibility genes compared with non-carriers from BRCA1 and BRCA2 families.     

Molecular analysis of the BRCA1 and BRCA2 genes in 32 breast and/or ovarian cancer Spanish families

It is estimated that about 5-10% of breast cancer cases may be due to inherited predisposition. Until now, two main susceptibility genes have been identified: BRCA1 and BRCA2. The first linkage and mutational studies suggested that mutations in these two genes would account for the majority of high-risk breast cancer families, but recent studies show how the proportion of families due to BRCA1 or BRCA2 mutations strongly depends on the population and the types of family analyzed. It is now clear that, in the context of families with a modest cancer profile, which are the most commonly found in the clinical practice, the percentage of mutations found is much lower than that suggested by the first studies. In the present study, we analyze a group of 32 Spanish families, which contained at least three cases of female breast cancer (at least one of them diagnosed before the age of 50 years), for the presence of mutations in the BRCA genes. The total proportion of mutations was low (25%), although the percentage of mutations in the BRCA1 and BRCA2 genes was higher, considering the breast and ovarian cancer families and the male breast cancer families respectively. Our results are in agreement with the idea that a great proportion of moderate-risk cancer families could be due to low penetrance susceptibility genes distinct from BRCA1 or BRCA2.     

The influence of familial and hereditary factors on the prognosis of breast cancer

Background: Family history is a well recognized risk factor for breast cancer, but its impact in terms of breast cancer survival is uncertain. The recent identification of breast cancer predisposing genes has provided new clinical insights in this field.Design: English literature identified through Medline between 1976 and February 1999 was reviewed including search terms: breast cancer, survival, prognosis, family history, genetics, BRCA1, BRCA2, and related articles.Results: Publications were divided into three categories.Family history-based studies: eighteen articles were reviewed. Four studies showed a statistically significant better survival in patients with a family history of breast cancer, and two studies demonstrated a significantly worse prognosis in this context. The remaining articles showed no significant difference. Linkage studies: Two studies based on linkage to BRCA1 found that overall survival was better in linked families. A third one concluded to a worse outcome in BRCA2-linked tumors. Mutation-based studies: 10 studies looking at the association between germ-line mutations in BRCA1/BRCA2 and clinical outcomes were reviewed. Eight articles reported no significant difference in outcome, whereas two studies showed a worse outcome in patients with mutations.Conclusions: Conflicting data exist as to whether the prognosis of familial or hereditary breast cancer differs from that of sporadic cases. Some of the discrepancies may be explained by methodological differences or biases. However, no studies showed a survival advantage for BRCA1mutation carriers. This seems to indicate that BRCA1-related breast cancer is not associated with a survival advantage, and that in fact, certain BRCA1 germline mutations confer a worse prognosis. However, to adequately answer this question, more efficient molecular tools to identify all the genetic changes responsible for breast cancer predisposition, and large cohort studies to evaluate their clinical consequences, are needed.     

BRCA1 and BRCA2 mutations in Turkish breast/ovarian families and young breast cancer patients

To date, BRCA1 and BRCA2 mutations in breast and/or ovarian patients have not been characterized in the Turkish population. We investigated the presence of BRCA mutations in 53 individuals with a personal and family history of breast and/or ovarian cancer, and 52 individuals with a personal history of breast cancer diagnosed below age 50 without additional family history. We have identified 11 mutations (nine BRCA1 and two BRCA2) using combined techniques involving protein truncation test, direct sequencing and heteroduplex analysis. We found eight out of 53 patients (15.1%) with a family history to carry BRCA gene mutations (seven BRCA1 and one BRCA2). Of these, four were found in 43 families presenting only breast cancer histories, and four were found in families presenting ovarian cancer with or without breast cancer. We also demonstrated two BRCA1 and one BRCA2 mutations in three out of 52 (5.8%) early-onset breast cancer cases without additional family history. Three of nine BRCA1 and both BRCA2 mutations detected in this study were not reported previously. These mutations may be specific to the Turkish population. The BRCA1 5382insC mutation, specific to Ashkenazi and Russian populations, was found twice in our study group, representing a possible founder mutation in the Turkish population.     

Limited relevance of the CHEK2 gene in hereditary breast cancer

To establish the importance of CHEK2 mutations for familial breast cancer incidence in the German population, we have screened all 14 of the coding exons in 516 families negative for mutations in both the BRCA1 and BRCA2 genes. We found 12 distinct variants in 30 unrelated patients (5.81%), including 5 that are novel and an additional 4 found for the first time in breast cancer. These aberrations were evaluated in 500 healthy women aged over 50 years and in the case of the 2 exon 10 mutations, 1100delC and 1214del4bp, in 1315 randomized healthy controls. According to our results, a statistically significant association for the exon 10 mutations was observed (p = 0.006). The prevalence of the 1100delC mutation in the German population, however, is significantly lower than those reported for other Caucasian populations both in familial breast cancer patients (1.6%) and controls (0.5%), and shows independent segregation with breast cancer in 2 of 4 families analyzed. The remaining 10 variants were more abundant in patients (21) compared to the controls (12) although the difference was not statistically significant. Interestingly, we found no increased breast cancer risk associated with the splice site mutation IVS2+1G-->A or the most common missense mutation I157T, which account for more than half (12/21) of the variants observed in patients. The low prevalence and penetrance of the exon 10 deletion mutations together with no, or an uncertain elevation in risk for other CHEK2 mutations suggests a limited relevance for CHEK2 mutations in familial breast cancer. Further evaluation of the unique variants observed in breast cancer is required to determine if they may play a role in a polygenic model of familial breast cancer. Nevertheless, it seems premature to include CHEK2 screening in genetic testing.     

The impact of having relatives affected with breast cancer on psychological distress in women at increased risk for hereditary breast cancer

Purpose.Being at hereditary risk of breast cancer (BC) may lead to elevated levels of distress because of the impact of the BC-process in relatives.Objective.Determine the association between psychological distress and BC in relatives. We studied: kind of kinship with the affected relative(s), degree of involvement with the relatives BC, time elapsed since the BC diagnosis of the relative, and loss of a relative as a consequence of BC.Methods.The study cohort consisted of women at increased risk of developing BC, adhering to regular surveillance and participating in the Dutch MRISC-study. Two months prior to the surveillance appointment, demographics, general and BC specific distress and experience with BC in the family were assessed.Results.347 out of 351 participants (mean age 40 1/2) had at least one relative affected with BC. The following variables were significantly, positively related to BC specific distress: having at least one affected sister (n=105; p < 0.04); close involvement in a sisters BC process (n=94; p < 0.03); and a recent (less than three years ago) BC diagnosis in a sister (n=30; p < 0.03). General distress did not show any significant associations with the experience of BC in the family.Conclusion. These findings show the impact of a BC diagnosis in a sister, particularly a recent diagnosis, on psychological distress. Women who have experienced BC in their sister may be in need of additional counselling or of more attention during the surveillance process.     

BRCA1 andBRCA2 germline mutations in Japanese with hereditary breast cancer families

We examined germline mutations inBRCA1 andBRCA2 in 23 Japanese breast cancer families, using PCR-SSCP analysis. The same nonsense mutation (exon 5, Leu63ter) ofBRCA1 was detected in two different families. Three different mutations resulting in a truncatedBRCA2 protein (exon 9, 20, 24) were detected in three different families, including one male case of breast cancer. One base substitution mutation inBRCA2, A10462G, was detected in the other two families. Although the mean age of onset for breast cancer in families with theBRCA1- mutation was 50 years, the age of onset in families with theBRCA2-mutation was from 28 to 43 years. Among the 23 families examined, two families had members with ovarian cancers, three had members with prostate cancers, and one had a pancreatic cancer. However, none of these families was positive for theBRCA1 orBRCA2 mutation. Histopathologically, we observed a prevalence of histological grade 3 inBRCA2-associated familial breast cancers, because of nuclear atypia, structural atypia and mitotic activity. It is suggested thatBRCA2 may play a more important role thanBRCA1 in Japanese familial breast cancers, and these mutations are related to the aggressive nature and highly proliferative activity of the tumors.     

A high proportion of founder BRCA1 mutations in Polish breast cancer families

Three mutations in BRCA1 (5382insC, C61G and 4153delA) are common in Poland and account for the majority of mutations identified to date in Polish breast and breast-ovarian cancer families. It is not known, however, to what extent these 3 founder mutations account for all of the BRCA mutations distributed throughout the country. This question has important implications for health policy and the design of epidemiologic studies. To establish the relative contributions of founder and nonfounder BRCA mutations, we established the entire spectrum of BRCA1 and BRCA2 mutations in a large set of breast-ovarian cancer families with origins in all regions of Poland. We sequenced the entire coding regions of the BRCA1 and BRCA2 genes in 100 Polish families with 3 or more cases of breast cancer and in 100 families with cases of both breast and ovarian cancer. A mutation in BRCA1 or BRCA2 was detected in 66% of breast cancer families and in 63% of breast-ovarian cancer families. Of 129 mutations, 122 (94.6%) were in BRCA1 and 7 (5.4%) were in BRCA2. Of the 122 families with BRCA1 mutations, 119 (97.5%) had a recurrent mutation (i.e., one that was seen in at least 2 families). In particular, 111 families (91.0%) carried one of the 3 common founder mutations. The mutation spectrum was not different between families with and without ovarian cancer. These findings suggest that a rapid and inexpensive assay directed at identifying the 3 common founder mutations will have a sensitivity of 86% compared to a much more costly and labor-intensive full-sequence analysis of both genes. This rapid test will facilitate large-scale national epidemiologic and clinical studies of hereditary breast cancer, potentially including studies of chemoprevention.     

Screening for common mutations in BRCA1 and BRCA2 genes: interest in genetic testing of Tunisian families with breast and/or ovarian cancer

BackgroundIn the Tunisian population, as yet a limited number of BRCA1/2 germline mutations have been reported in hereditary breast and/or ovarian cancer. These mutations are located in a few exons of BRCA1/2. The aim of the present study was to search for these mutations in 66 unrelated patients with hereditary breast and/or ovarian cancer in order to assess the interest in such a targeted approach for genetic testing in Tunisia.Materials and MethodsBlood specimens from the 66 Tunisian patients, with family history of breast and/or ovarian cancer, were collected at the Salah Azaiz Cancer Institute of Tunis. The exons 5, 20 and part of exon 11 of BRCA1 as well as part of exons 10 and 11 of BRCA2 were analyzed by Sanger sequencing.Results12 patients had deleterious mutations in the BRCA1 or BRCA2 genes (18%), including a novel frame-shift mutation of BRCA1 (c.3751dup; 3780insT). Four distinct BRCA1 mutations were detected eight patients: c.5266dup (5382insC) and c.211dup (330insA) each in three patients, c.3751dup (3870insT) and c.4041_4042del (4160delAG) each in one patient. The four remaining cases all carried the same BRCA2 mutation, c.1310_1313del (1538delAAGA). Besides these deleterious mutations, eight polymorphisms and unclassified variants were detected, one of them being never reported (BRCA1c.3030T>G, p.Pro1010Pro).ConclusionIn this study, we show that targeting relevant exons in BRCA1 and BRCA2 genes allows detection of a substantial percentage of mutations in the Tunisian population. Therefore such an approach may be of interest in genetic testing of high-risk breast and ovarian cancer families in Tunisia.     

Prevalence of the BRCA1 founder mutation c.5266dupin Brazilian individuals at-risk for the hereditary breast and ovarian cancer syndrome

About 5-10% of breast and ovarian carcinomas are hereditary and most of these result from germline mutations in the BRCA1 and BRCA2 genes. In women of Ashkenazi Jewish ascendance, up to 30% of breast and ovarian carcinomas may be attributable to mutations in these genes, where 3 founder mutations, c.68_69del (185delAG) and c.5266dup (5382insC) in BRCA1 and c.5946del (6174delT) in BRCA2, are commonly encountered. It has been suggested by some authors that screening for founder mutations should be undertaken in all Brazilian women with breast cancer. Thus, the goal of this study was to determine the prevalence of three founder mutations, commonly identified in Ashkenazi individuals in a sample of non-Ashkenazi cancer-affected Brazilian women with clearly defined risk factors for hereditary breast and ovarian cancer (HBOC) syndrome. Among 137 unrelated Brazilian women from HBOC families, the BRCA1c.5266dup mutation was identified in seven individuals (5%). This prevalence is similar to that encountered in non-Ashkenazi HBOC families in other populations. However, among patients with bilateral breast cancer, the frequency of c.5266dup was significantly higher when compared to patients with unilateral breast tumors (12.1% vs 1.2%, p = 0.023). The BRCA1 c.68_69del and BRCA2 c.5946del mutations did not occur in this sample. We conclude that screening non-Ashkenazi breast cancer-affected women from the ethnically heterogeneous Brazilian populations for the BRCA1 c.68_69del and BRCA2 c.5946del is not justified, and that screening for BRCA1c.5266dup should be considered in high risk patients, given its prevalence as a single mutation. In high-risk patients, a negative screening result should always be followed by comprehensive BRCA gene testing. The finding of a significantly higher frequency of BRCA1 c.5266dup in women with bilateral breast cancer, as well as existence of other as yet unidentified founder mutations in this population, should be further assessed in a larger well characterized high-risk cohort.     

The risk of primary and contralateral breast cancer after ovarian cancer in BRCA1/BRCA2 mutation carriers

BACKGROUND:

The objective of this study was to assess the incidence of primary breast cancer (PBC) and contralateral breast cancer (CBC) in patients who had BRCA1/BRCA2‐associated epithelial ovarian cancer (OC).

METHODS:

From the database of the Rotterdam Family Cancer Clinic, patients who had BRCA‐associated OC without a history of unilateral breast cancer (BC) (at risk of PBC; n = 79) or with a history of unilateral BC (at risk of CBC; n = 37) were selected. The control groups consisted of unaffected BRCA mutation carriers (n = 351) or mutation carriers who had a previous unilateral BC (n = 294), respectively. The risks of PBC and CBC were calculated using the Kaplan‐Meier survival method with death considered as a competing risk event.

RESULTS:

Women with BRCA‐associated OC had lower 2‐year, 5‐year, and 10‐year risks of PBC (3%, 6%, and 11%, respectively) compared with unaffected mutation carriers (6%, 16%, and 28%, respectively; P = .03), although they had a considerably higher mortality rate at similar time points (13%, 33%, and 61%, respectively, vs 1%, 2%, and 2%, respectively; P < .001). In BRCA mutation carriers with a previous unilateral BC, the 2‐year, 5‐year, and 10‐year risks of CBC were nonsignificantly lower in patients with OC than in those without OC (0%, 7%, and 7%, respectively, vs 6%, 16%, and 34%, respectively; P = .06), whereas the mortality rate was higher in patients with OC (19%, 34%, and 55%, respectively, vs 4%, 11%, and 21%, respectively; P < .001).

CONCLUSIONS:

Patients with BRCA‐associated OC had a lower risk of developing a subsequent PBC or CBC than mutation carriers without OC, whereas the risk of dying from OC was greater than the risk of developing BC. These data may facilitate more tailored counseling for this patient subgroup, although confirmative studies are warranted. Cancer 2013. © 2012 American Cancer Society.     

Predictors of contralateral breast cancer in BRCA1 and BRCA2 mutation carriers

Purpose:

The objective of this study was to estimate the risk of contralateral breast cancer in BRCA1 and BRCA2 carriers; and measure the extent to which host, family history, and cancer treatment-related factors modify the risk.

Patients and methods:

Patients were 810 women, with stage I or II breast cancer, for whom a BRCA1 or BRCA2 mutation had been identified in the family. Patients were followed from the initial diagnosis of cancer until contralateral mastectomy, contralateral breast cancer, death, or last follow-up.

Results:

Overall, 149 subjects (18.4%) developed a contralateral breast cancer. The 15-year actuarial risk of contralateral breast cancer was 36.1% for women with a BRCA1 mutation and was 28.5% for women with a BRCA2 mutation. Women younger than 50 years of age at the time of breast cancer diagnosis were significantly more likely to develop a contralateral breast cancer at 15 years, compared with those older than 50 years (37.6 vs 16.8% P=0.003). Women aged <50 years with two or more first-degree relatives with early-onset breast cancer were at high risk of contralateral breast cancer, compared with women with fewer, or no first-degree relatives with breast cancer (50 vs 36% P=0.005). The risk of contralateral breast cancer was reduced with oophorectomy (RR 0.47; 95% CI 0.30–0.76; P=0.002).

Conclusion:

The risk of contralateral breast cancer risk in BRCA mutation carriers declines with the age of diagnosis and increases with the number of first-degree relatives affected with breast cancer. Oophorectomy reduces the risk of contralateral breast cancer in young women with a BRCA mutation.     

Male breast cancer: Progress, prognosis and future pathways

Breast cancer is one of the most commonly treated malignancies worldwide, but is rare in males. Less than one percent of all breast cancers occur in men, and breast cancer comprises less than one percent of all male malignancies. Thus, clinical experience in managing this condition is limited. In contrast to female breast cancer, much remains unknown about breast cancer in males. While there are similarities between the two, emerging data suggest that there are perhaps more differences than previously thought. Nevertheless, much of how males with breast cancer are managed continues to be extrapolated from randomised trials performed in females, due to lack of data in the male population alone. Another poorly understood aspect is the psychological impact experienced by male patients when diagnosed with what is generally thought of as a female malignancy. This review will discuss the known epidemiology, demographics, risk factors and genetic predispositions surrounding the development of breast cancer in males; as well as current surgical and radiotherapeutic interventional techniques. Histological profiles and subtypes as well as hormone receptor and HER‐2 receptor status are also discussed, with an overview of chemotherapy and hormonal strategies in both the adjuvant and metastatic settings.     

Influence of selected lifestyle factors on breast and ovarian cancer risk in BRCA1 mutation carriers from Poland

Summary It has been estimated that the lifetime risk of breast cancer among women who inherit a BRCA1 or BRCA2 mutation is as high as 80%, and the risk estimates for ovarian cancer range from 15 to 40%. Several environmental and lifestyle factors are believed to contribute to the development of breast cancer in the general population and it is of interest to establish if these factors operate among mutation carriers as well. To evaluate the effects of age of menarche, parity, breast-feeding, oophorectomy and oral contraceptive use, as well as smoking and coffee consumption, on the risks of breast and ovarian cancer, we conducted a matched case–control study of Polish women with BRCA1 mutations. There were 348 breast cancer patients, 150 ovarian cancer patients and similar numbers of age-matched controls. BRCA1 carriers with late age of menarche, lower parity and long-term breast-feeding were less likely to develop breast cancer. Oral contraceptives protected against ovarian cancer.     

Factors influencing ovulation and the risk of ovarian cancer in BRCA1 and BRCA2 mutation carriers

The role of the lifetime number of ovulatory cycles has not been evaluated in the context of BRCA‐associated ovarian cancer. Thus, we conducted a matched case–control study to evaluate the relationship between the cumulative number of ovulatory cycles (and contributing components) and risk of developing ovarian cancer in BRCA mutation carriers (1,329 cases and 5,267 controls). Information regarding reproductive and hormonal factors was collected from a routinely administered questionnaire. Conditional logistic regression was used to evaluate all associations. We observed a 45% reduction in the risk of developing ovarian cancer among women in the lowest vs. highest quartile of ovulatory cycles (OR = 0.55; 95% CI 0.41–0.75, p = 0.0001). Breastfeeding for more than 12 months was associated with a 38% (95% CI 0.48–0.79) and 50% (95% CI 0.29–0.84) reduction in risk among BRCA1 and BRCA2 mutation carriers, respectively. For oral contraceptive use, maximum benefit was seen with five or more years of use among BRCA1 mutation carriers (OR = 0.50; 95% CI 0.40–0.63) and three or more years for BRCA2 mutation carriers (OR = 0.42; 95% CI 0.22–0.83). Increasing parity was associated with a significant inverse trend among BRCA1 (OR = 0.87; 95% CI 0.79–0.96; p‐trend = 0.005) but not BRCA2 mutation carriers (OR 0.98; 95% CI 0.81–1.19; p‐trend = 0.85). A later age at menopause was associated with an increased risk in women with a BRCA1 mutation (OR trend = 1.18; 95% CI 1.03–1.35; p = 0.02). These findings support an important role of breastfeeding and oral contraceptive use for the primary prevention of ovarian cancer among women carrying BRCA mutations.