Breast cancer is one of the most often female cancers. From the last few years in Poland morbidity increased about 4 5%. This cancer is also cause of the major part of deaths caused by malignant tumors. Etiology of most cases of breast cancer is not possible to determine. The most important risk factors are age and breast cancer occurrence in first and/or second step relatives. Germinal mutations in two major high penetrance genes, BRCA1 and BRCA2 are responsible for high risk of cancer development but they constitute less than 5% of all cases of this cancer.