Validation of p53 immunohistochemistry as a prognostic factor in breast cancer in clinical practice

Context.-Abnormal p53 tumor suppressor gene expression as detected by immunohistochemistry is a possible prognostic factor in breast cancer. The difference in techniques used to evaluate the expression of mutated p53 protein is under intense scrutiny, as well as its uses either independently or in conjunction with other prognostic factors in breast cancer. Objective.-To determine whether p53 immunohistochemistry can be used as a reliable indicator of the presence of mutated nuclear p53 protein, and whether this method can be performed reliably in a community hospital's clinical practice. Design.-One hundred twenty-two cases of breast carcinoma were stained and analyzed for the presence of p53 protein using DO-7 (Dako Corporation, Carpinteria, Calif) p53 antibody. Results.-Of the 122 cases of invasive carcinoma studied, 23 (18.7%) were positive for p53, and 16 (16.3%) of 98 cases with coexisting ductal carcinoma in situ were positive for p53. This finding is in agreement with comparable published studies. Conclusions.-Based on the results of this study, we conclude that p53 immunohistochemistry qualifies as a diagnostic technique suitable for clinical practice in a community hospital. Its detection may be particularly promising in clinical trials of new molecular therapies directed at the p53 tumor suppressor gene.