In women, who are BRCA1/2 gene mutation carriers, the risk of breast cancer development is about 50-80%, of ovarian cancer – about 40%, and about 10% of the uterine tube and peritoneal cancer. One of the options, except chemoprevention, in women who are BRCA1 gene mutation carriers, is prophylactic adnexectomy, which significantly reduces the risk of the above cancers development. Prophylactic adnexectomy reduces the risk of ovarian cancer development to 5% and the risk of breast cancer development to 30-40%. In the group of women, who are BRCA1 gene mutation carriers, the changes in expression of the other genes, that can modify occurrence of the breast or ovarian cancer, is being searched. Also, the preneoplastic changes in their ovaries are still being searched. Our studies, concerning the TP53, BRCA1, NM23 and KAI1 proteins expression in that group of women, did not demonstrate important changes because of too low quantity, but they seem to be promising, particularly in the range of BRCA1 and KAI1 mutations.