p53 expression in human breast cancer related to survival and prognostic factors: an immunohistochemical study.

In a study of 90 breast cancer patients, tumour p53 protein expression was determined by immunohistochemistry using the monoclonal antibody PAb1801. Patient lymph node status and Bloom's grade were determined, and both oestrogen and progesterone status assessed, also by immunohistochemistry. Lymph node status, tumour grade, and progesterone receptor status all had a significant influence on survival. Patients with p53-positive tumours showed poorer survival but this did not achieve significance. p53 protein expression showed a significant relationship to high tumour grade and a weak correlation with negative oestrogen receptor status. The data suggest that p53 protein expression may be a marker of more aggressive carcinomas but that the prognostic power of expression is likely to be weak and unlikely, therefore, to be of clinical value. The results do not resolve whether detectable p53 protein expression represents a random product of dedifferentiation, or an important feature of the malignant phenotype, playing a key role in tumour behaviour. The number of patients in our study is small, however, and investigation of a larger series is clearly indicated.