BACKGROUND.
Prostate specific membrane antigen (PSM) is a membrane-bound antigen that is highly specific for benign and malignant prostate epithelial cells. Its expression in high grade prostatic intraepithelial neoplasia (PIN) has not been compared with that in prostate carcinoma.
METHODS.
The authors performed an immunohistochemical study of representative sections from 184 radical prostatectomies from previously untreated patients with pathologic stage T2N0M0 adenocarcinoma treated at the Mayo Clinic between 1987 and 1991. Affinity-purified monoclonal antibody 7E11-5.3 directed against PSM was employed at a concentration of 20 g/mL overnight. For comparison, serial sections in each case were stained with prostate specific antigen (PSA). Staining for all antibodies was performed using the streptavidinbiotin method. For each case, the percentage of immunoreactive cells in benign epithelium, PIN, and adenocarcinoma was estimated in increments of 10%.
Cox proportional hazards models were used to identify the risk of carcinoma recurrence according to the number of immunoreactive PIN or cancer cells for PSM and PSA; the date of radical prostatectomy was used as the starting time, and serum PSA (biochemical) failure or clinical failure was the event. PSA biochemical failure was defined as serum PSA ΟΎ 0.2 ng/mL at least 30 days after surgery.