Use of OC was associated with breast cancer only for non-carriers (HR = 3.99, 95% CI 1.65–9.67), but no association was found for BRCA1 (HR = 1.24; 95% CI 0.45–3.40) and BRCA2 mutation carriers (HR = 0.71; 95% CI 0.21–2.37). The gene discussed is BRCA1; the disease is breast cancer.