A small number of studies have indicated that breast cancer risk is lower in BRCA1/BRCA2 mutation carriers after an ovarian cancer diagnosis, compared to unaffected mutation carriers (Domchek et al. 2013; Gangi et al. 2014; McGee et al. 2017; Vencken et al. 2013). This evidence concerns the gene BRCA2 and ovarian carcinoma.