Prostate-specific antigen (PSA) in the management of 500 prostatic patients

Blood samples from 500 patients with clinical prostatic symptoms were radioimmunoassayed with prostate-specific antigen (PSA) and prostatic acid phosphatase (PAP) kits. On the basis of histological data, directed by PSA results and other investigations, 200 prostatic cancers (adenocarcinomas), 276 benign prostatic hypertrophy (BPH), 16 cases of prostatitis, 5 cancers of the bladder, and 3 prostatodynias were diagnosed. All of the serum samples from prostatic cancer patients showed elevated PSA levels at diagnosis, whereas about 70% of these showed normal PAP values. The sensitivity of the PSA assay is 100% when 2.5 ng/ml is taken as the upper limit of normal. However, the specificity and the positive predictive value are better at 10 ng/ml: 99 and 79%, respectively. High PSA values alerted the clinician when diagnosing a cancer without symptoms on rectal or ultrasonographic examination (3%). In BPH, when the PSA level is between 2.5 and 10 ng/ml, a PSA control must be performed within 2 months. If PSA increases above 10 ng/ml, the risk of cancer has to be considered. In the follow-up, PSA is a better marker than PAP to detect disease progression and seems to constitute an evolutive tumor mass index. PSA is the most sensitive, the earliest, and the most prognostically reliable marker for diagnosis and follow-up of prostate cancer patients.