Clinical behaviour of prostatic specific antigen and prostatic acid phosphatase: a comparative study.

We assayed prostatic specific antigen (PSA) and prostatic acid phosphatase (PAP) serum levels in 1383 patients using a double antibody radioimmunoassay (RIA) I125. Establishing the upper normal limit in 10 ng/ml PSA and 2.5 ng/ml for PAP, the false positive results were only 1.9 and 5.1 percent in men with non-prostatic benign or malignant pathology and respectively 0 and 2.2 percent in women. We detected false positive levels for these two tumoral markers in 3.5 and 4.7 percent of patients with non-complicated benign prostatic hypertrophy, 64.8 and 19.2 percent in complicated benign prostatic hypertrophy, 24 and 16 percent in acute prostatitis and 3.3 percent in chronic prostatitis. The sensitivity in patients with prostate cancer was 87.2 percent for PSA and 64.1 percent for PAP, and there was a better correlation with PSA than PAP for tumoral spread and histological grading. Finally, clinical efficacy was higher with PSA and was no better when both markers were assayed.