Does oral contraceptive use increase the risk of breast cancer in women with BRCA1/BRCA2 mutations more than in other women?

We conducted a study to determine whether the risk of breast cancer associated with oral contraceptive (OC) use is higher in women with BRCA1/BRCA2 mutations than in other women by examining whether breast cancer patients with these mutations were more likely than breast cancer patients without mutations in BRCA1/BRCA2 to have used OCs. We tested for BRCA1 185delAG and 5382insC and BRCA2 6174delT mutations in a population-based sample of 50 young Ashkenazi Jewish breast cancer patients. Nine patients (18%) had a BRCA1 mutation, and five patients (10%) had a BRCA2 mutation. Long-term OC use (>48 months) before a first full-term pregnancy was associated with an elevated risk of being classified as a mutBRCA carrier (odds ratio, 7.8; trend, P = 0.004). The results suggest that OC use may increase the risk of breast cancer more in mutBRCA carriers than in noncarriers; however, they must be interpreted with caution given the small sample size.