IMMUNOHISTOCHEMICAL DETECTION OF P53 PROTEIN AS A PROGNOSTIC INDICATOR IN PROSTATE-CANCER

Mutation of the p53 gene is the most common genetic alteration in huma n cancers. The mutant p53 protein is more stable than the wild type an d on be detected by immunohistology. The objective of the current stud y H-as to evaluate the immunohistological detection of p53 protein in prostate cancer and its utility as a prognostic indicator. We used a m onoclonal anti-p53 antibody and immunostained primary prostate adenoca rcinomas (stages Al to D1) from 109 patients with a mean follow-up of 3.8 years (range, 1.3 to 9.3 years). Immunoreactivity for p53 was seen in 23 cancers (21%). There were 12 instances of progression (14%) amo ng the p53-negative cancers versus seven (30%) among the p53-positive group. Survival analysis using three univariate statistical tests show ed that p53 reactivity (P<.03), Gleason score (P<.01), and stage (P<.0 5) had significant effects on time to progression of prostate cancer. Multivariate anal)ses showed that Gleason score was significant with a ll three tests; p53 reactivity was significant with the Wilcoxon test but only approached significance by the log rank and Cox tests. When t he analyses included only patients with Gleason scores 2 to 7 (N = 94) , univariate analyses showed that p53 reactivity was strongly related to progression of prostate cancer (P<.007). Stage also was significant (P<0.04), but Gleason score was not. Multivariate analyses showed onl y p53 reactivity to be significant (P<.007). In conclusion, mutation o f the p53 gene may be involved in prostate cancer carcinogenesis. p53 reactivity marks an aggressive subset of prostate cancer and appears t o be an independent prognostic indicator that is particularly valuable among the low to intermediate grade cancers. HUM PATHOL 26:106-109. C opyright (C) 1995 by W.B. Saunders Company