OCP use was not associated with increased contralateral breast cancer risk in BRCA2-mutation carriers (RR = 0.82; 95% CI = 0.21–3.13), and BRCA1-mutaion carriers who used the OCP trended towards a greater risk of contralateral breast cancer compared to nonusers, but this risk was not significant (RR = 2.38; 95% CI = 0.72–7.83). This evidence concerns the gene BRCA1 and breast carcinoma.