Breast cancer is the most common malignancy in women. Its estimated annual incidence is about one million cases worldwide. A number of risk factor have been identified, among them early menarche, late menopause, nulliparity and positive family history Moreover a number of highly penetrant breast and ovarian cancer susceptibility genes, such as BRCA 1 and BRCA2, have been identified. Recent findings suggest TopBP1 to be a breast and ovarian cancer susceptibility gene. Moreover; TopBPI protein may be an important prognostic marker of breast cancer TopBP1 protein is involved in DNA replication, mitosis and meiosis, as well as DNA repair Deregulation of these processes may have pathological implications in cancer