Clinico-pathological correlation and prognostic significance of nuclear p53 protein in colorectal cancer. Colorectal Cancer Study Group of the University and Health Care District of Modena.

Overexpression of p53 protein was studied in neoplastic specimens of 150 patients registered for colorectal adenocarcinoma in the Health Care District 16 of Modena, Italy, from 1984 to 1986. We selected Dukes' stage B (92) and C (58) patients whose survival and recurrence rates are not easily predictable, with the purpose of defining subgroups of patients at high risk of recurrence. Monoclonal antibody PAb 1801 was used on formalin-fixed, paraffin embedded specimens. Nuclear staining was assessed to divide tumours into three groups: a) negative, b) low expressors, c) high expressors. Histomorphological variables of tumours, major clinical features of the patients and 5-year specific survival, were evaluated and related to p53 status. p53 was found in 71 out of 150 cases (47.3%); 50 tumours were high and 21 low expressors. No correlation was found between p53 overexpression and clinico-pathological variables. No difference in survival was found between patients with p53 positive and negative tumours in the entire series or within Dukes' stage B and C patients. However, the subgroup of patients with stage C rectal cancer seemed to have a better prognosis if the tumour was p53 negative (of borderline significance, p = 0.15). The same results were obtained by grouping low expressor tumours alternatively with negative or high expressors. We conclude that p53 nuclear overexpression does not seem to influence the prognosis of Dukes' stage B or C colorectal cancer patients.