P53 EXPRESSION IN INCIDENTAL PROSTATIC-CANCER

Incidental prostate cancer is an indolent disease typically characteri zed by a benign clinical course. This is not clearly established, howe ver, as recent reports suggest that up to 27% of cases progress with l ong-term follow-up. The indolent history of this disease led initially to the hypothesis that mutations of the p53 gene would be an infreque nt event in this patient population. Archival specimens from 24 patien ts with Stage Al carcinomas were evaluated for abnormal p53 expression . In 23 patients the disease was diagnosed after transurethral resecti on for bladder outlet obstructive symptoms, and in one patient after a radical prostatectomy. Using a monoclonal antibody (PAb 240) and an i mmunohistochemical technique, a total of 36 microfoci of tumor were ev aluated. Thirteen (36%) microfoci were positive with an intense nuclea r staining pattern (2+), and eight (22%) microfoci had an intermediate staining pattern. Four areas of prostatic intraepithelial neoplasia a lso stained positively with a 2+ staining pattern. These results sugge st that abnormal p53 expression is a feature of a significant number o f incidental prostatic carcinomas and that this occurrence is an early event in the development of the malignant phenotype.