Prostate-specific membrane antigen levels in sera from healthy men and patients with benign prostate hyperplasia or prostate cancer

Prostate-specific membrane antigen (PSMA) serum levels have been proposed t o be of prognostic significance in patients with advanced prostate disease. The objective of the present study was to confirm PSMA serum expression by Western blot techniques, to determine whether such data could assist in th e differentiation of benign from malignant prostatic disease, and to determ ine the suitability of serum PSMA measurements in predicting recurrent or p rogressive prostate malignancies, We measured PSMA, a transmembrane glycopr otein identified in prostate epithelial cells, in the sera of 236 normal in dividuals and cancer patients by Western blot analysis. Within the normal m ale population, PSMA levels increase with age and were found to be signific antly elevated in subjects more than 50 years of age when compared to those of younger men. We did not confirm previous reports that serum PSR-IA meas urements could distinguish late-stage prostate carcinoma from early-stage p rostate carcinoma, nor did we find PSMA to be more effective than prostate- specific antigen in monitoring prostate cancer patient prognosis. Furthermo re, we found elevated serum PSMA in healthy females, and, similar to the he althy male population, the levels increased with age, with the highest leve ls found in the sera from breast cancer patients. These latter observations further support that PSMA is not a specific biomarker for prostate cancer and that a variety of normal and diseased tissue may contribute to the seru m levels of PSMA.