EVALUATION OF P53 PROTEIN EXPRESSION AS A MARKER FOR LONG-TERM PROGNOSIS IN COLORECTAL-CARCINOMA

Mutation of the p53 gene is reported to be of prognostic importance in colorectal carcinomas. Immunohistochemical staining of the accumulate d p53 gene product may be a simple alternative for p53 mutation analys is. Previous studies addressing the prognostic importance of p53 expre ssion, however, yielded contradictory results. Therefore, we evaluated the importance of p53 expression as a marker for long-term prognosis in a well-characterised study population of 109 colorectal carcinomas. After antigen retrieval with target unmasking fluid (TUF), immunostai ning of p53 was performed with both monoclonal antibody DO7 and polycl onal antibody CM1. Objective quantification of the p53 signal was asse ssed by a computerised image analyser. p53 expression was higher in no n-mucinous tumours than in mucinous rumours (p53 labelling index = 30% and 17% respectively, P = 0.05), and in metastatic tumours compared w ith non-metastatic tumours (p53 labelling index = 37% and 22% respecti vely, P = 0.05). Other histopathological features were not related to p53 expression. In multivariate analysis, Dukes' stage (P = 0.02) and histological grade (P = 0.05) stood out as independent markers for pro gnosis. p53 expression was not an independent marker for prognosis. At present, p53 expression is not a useful marker for long-term prognosi s. Further insight into the relationship between p53 mutations and p53 expression is needed to elucidate more precisely the clinical relevan ce of p53 alterations.