Overexpression of p53 and prognosis in breast cancer.

Assessment of prognostic markers in breast cancer independent of the axillary lymph node status is of major concern for the application of adjuvant treatment regimens. The current treatment decision is based mainly on the axillary lymph node status. Because of improved screening methods, the number and proportion of patients with node-negative disease are increasing, which warrants a search for reliable prognostic parameters. The application of tumor suppressor gene expression appears to be especially suited as a marker of the progress in malignant cellular dedifferentiation. Tumor tissues of 156 patients with primary invasive breast cancer were analyzed immunohistochemically for the presence of p53 protein in paraffin-embedded material. The reaction to monoclonal antibody PAb1801 yielded better results than did reactions to monoclonal antibody DO1 and polyclonal antibody CM-1. The significance of the immunohistochemical data was compared with a panel of established risk factors. Nuclear accumulation of p53 protein proved to be an independent marker of dedifferentiation, regardless of the lymph node status. Tumors showing p53 immunoreactivity were significantly more often related with histological Grade 3 and the absence of steroid hormone receptors. Kaplan-Meier estimation and multivariate analysis of disease-free and overall survival rate corroborated the importance of p53 as a prognostic parameter. Overexpression of p53 protein emerged as a reliable and independent predictor for disease recurrence and reduced survival rates in patients with breast cancer.