P53 IN BREAST-CANCER - ITS RELATION TO HISTOLOGICAL GRADE, LYMPH-NODE STATUS, HORMONE RECEPTORS, CELL-PROLIFERATION FRACTION (KI-67) AND C-ERBB-2 - IMMUNOHISTOCHEMICAL STUDY OF 153 CASES

The mutation of the p53 gene is a common phenomenon in numerous human tumors, leading to the accumulation of nonfunctioning p53 protein in the cell nucleus, which can be detected by immunohistochemistry. In breast cancer, it has been suggested that the overexpression of p53 protein in the nucleus is an indicator of poor prognosis, which must be borne in mind in selecting coadjuvant treatment for each patient. This study is an immunohistochemical analysis of p53 expression in 153 cases of mammary carcinoma, correlating it with histological grade, axillary node status, hormone receptors, cell-proliferation fraction and expression of the c-erbB-2 oncoprotein. Of all the breast-cancer tissue analyzed, 43.79% was positive for p53. The overexpression of this protein bears a direct statistically significant relationship to histological grade, cell-proliferation fraction and c-erbB-2, and an inverse relationship to estrogen and progesterone receptors. No statistically significant relationship was found with axillary node status. The expression of p53 in poorly differentiated tumors-commonly receptor negative and with a high proliferation fraction-may indicate greater tumor agressiveness and a high risk of relapse.