CYTOGENETIC ABNORMALITIES IN AN IN-SITU DUCTAL CARCINOMA AND 5 PROPHYLACTICALLY REMOVED BREASTS FROM MEMBERS OF A FAMILY WITH HEREDITARY BREAST-CANCER

Short-term cultures of tissue samples from three bilateral prophylacti c mastectomies and one in situ ductal carcinoma from four women belong ing to a family with hereditary breast cancer were cytogenetically ana lyzed. Clonal chromosome abnormalities were detected in five of the si x prophylactically removed breasts, all of which had the histologic di agnosis epithelial hyperplasia without atypia, and in the in situ carc inoma. The same karyotypic imbalance, a loss of 3p12-14, was detected in the in situ carcinoma as well as in one of the hyperplasias, indica ting that these bands may harbor a pathogenetically relevant gene in t his breast cancer family. The finding of chromosome aberrations in clo nal proportions in the prophylactically removed breasts indicates that a neoplastic process was already present, lending support to the view that prophylactic bilateral mastectomy in these high-risk individuals prevented the development of breast carcinoma.