One of the largest case control studies to assess this effect of oral contraceptives found a reduced risk of ovarian cancer in carriers of BRCA1 mutations (odds ratio 0.56 (95% CI 0.45–0.71); p < 0.0001) and carriers of BRCA2 mutations (0.39 (95% CI 0.23–0.66); p = 0.0004) [35]. This evidence concerns the gene BRCA1 and ovarian cancer.