Oktay, K. discovered that, of 126 breast cancer women, the BRCA mutation carriers had fewer ovarian oocytes than the non-carriers after stimulating their ovaries with Letrozole and gonadotropinss, an women with a positive BRCA1 mutation produced fewer ovarian oocytes and were 38.3 times more likely to have a low response than women with a positive BRCA2 mutation [45]. This evidence concerns the gene BRCA2 and breast cancer.