Immunohistochemical detection of carcinoma in radical prostatectomy specimens following hormone therapy

Following hormone therapy, residual carcinoma is frequently difficult to identify on HE‐stained prostatectomy specimens. The aim of the present study was therefore to investigate whole‐mounted specimens obtained by radical prostatectomy from patients who had undergone hormone therapy. Formalin‐fixed and paraffin‐embedded specimens were immunostained with prostate secretory cell markers including prostate‐specific antigen (PSA), P504S (α‐methylacyl‐coenzyme A racemase, AMACR), P501S (prostein), and prostate‐specific membrane antigen (PSMA). Residual carcinoma was detected in 250 histological slides of 42 patients in a total of 497 slides from 45 patients. In five of 250 slides (2%), carcinoma was not able to be recognized on HE‐stained slides, but was found on the immunohistochemistry slides. PSMA had reacted positively beyond a moderate degree in carcinoma from all patients. PSA was positive for carcinoma in most of the patients, while negative or minimal staining was observed in a small number of patients. Carcinoma was positively reactive with P504S and P501S in most of the patients, but was negatively reactive in a few. The Gleason score for a pretreatment needle biopsy correlated with P504S staining of the prostatectomy specimens. P504S and P501S had limited ability to identify degenerated carcinoma. PSMA was the most useful marker to identify carcinoma after hormone therapy.