Invariant p53 immunostaining in primary and recurrent breast cancer.

In animal models, acquired mutations of the p53 gene that result in increased p53 protein expression are associated with tumour recurrence following chemotherapy. The aim of this study was to test the hypothesis that breast cancer recurrences following adjuvant therapy exhibit aberrant p53 expression. We therefore evaluated p53 expression in paired primary and recurrent breast tumours: 48% of primary and 32% of recurrent tumours had abnormally increased p53 expression. Of the paired samples, 84% showed no change in p53 expression between the primary tumour and the metastasis. In fact, in no case was low (normal) p53 expression in the primary tumour followed by the development of high (aberrant) p53 expression in the recurrence. These results show that increased p53 expression is not selected for in the malignant cells emerging following adjuvant therapy, suggesting that p53 expression is unlikely to play a central role in breast cancer recurrences.