Expression of p53 and bcl-2 and response to preoperative chemotherapy and radiotherapy for locally advanced squamous cell carcinoma of the oesophagus.

AIMS To investigate the immunohistochemical expression of p53 and bcl-2 proteins in squamous cell carcinoma (SCC) of the oesophagus and to assess whether expression of these oncoproteins can be used to stratify patients into groups with a favourable or unfavourable response to preoperative chemo/radiotherapy. METHODS The initial diagnostic biopsy and the corresponding resected samples were obtained from 22 consecutive patients with SCC. All patients underwent preoperative chemo/radiotherapy. Tumour sections were incubated with a monoclonal antibody directed against p53 (DO-7). Twenty four non-neoplastic oesophageal biopsy specimens immunostained for p53 served as controls. Twelve randomly chosen sections from the 22 SCC samples were immunostained to test for bcl-2 protein expression. RESULTS After chemo/radiotherapy, 12 (55%) of the 22 patients had no evidence of tumour in the resected oesophagus. Before chemoradiotherapy, however, 17 (77%) patients were p53 positive. After treatment, residual carcinoma was detected in seven (41%) of the 17 p53 positive patients. All non-responsive cases had the same p53 immunopattern as before treatment. Bcl-2 immunoexpression was detected in six (50%) of 12 patients. Residual tumour was detected in the residual oesophagus in two (33%) of the six bcl-2 positive patients. After treatment, bcl-2 expression was no longer detected in the residual neoplastic cells of a previously bcl-2 positive tumour. Using Fisher's exact test no significant association was found between oncoprotein expression and response to preoperative treatment. CONCLUSION This study confirms the observation that p53 protein is frequently expressed in SCCs of the oesophagus, probably as a result of a mutation of the TP53 gene. However, no significant association was found between oncoprotein expression and response to chemo/radiotherapy. Anticancer agents do not seem to modify the expression of p53 and bcl-2 proteins.