Sensitive prostate specific antigen measurements identify men with long disease-free intervals and differentiate aggressive from indolent cancer recurrences within 2 years after radical prostatectomy.

Abstract

Commonly available prostate specific antigen (PSA) assays have detection limits of greater than 0.05 ng/ml., limiting their ability to identify residual or recurrent prostate cancer after radical prostatectomy or to provide prognostic information within the first several years after surgery. We investigated the ability of a sensitive PSA assay to identify residual prostate cancer and men at risk for early recurrence after radical prostatectomy. We measured PSA in 1,037 serum samples obtained serially from 127 men after radical prostatectomy using the IMMULITE third generation PSA assay. The IMMULITE PSA assay has an analytical sensitivity of less than 0.002 ng./ml. and a clinically useful decision threshold of 0.01 ng./ml. With this assay our patients were classified into 3 groups: 1) 50 with a postoperative baseline PSA of less than 0.01 ng./ml. that did not change during an average of 36 months postoperatively, 2) 66 with increasing PSA that exceeded 0.01 ng./ml. in all cases by 30 months postoperatively (20 with clinical cancer recurrences) and 3) 11 with slowly increasing PSA of greater than 0.01 but less than 0.02 ng./ml. at an average of 36 months postoperatively. The IMMULITE PSA assay provides clinically useful information not previously available from PSA assays with conventional sensitivity, which is highly predictive of cancer activity in patients within 2 years after radical prostatectomy.