Evaluation of prostate-specific antigen and prostatic acid phosphatase in untreated prostatic carcinoma and benign prostatic hyperplasia.

Prostate specific acid phosphatase (PAP) (Abbott, solid-phase enzyme immunoassay) and prostate specific antigen (PSA) (Hybritech, immunoradiometric assay) were determined in 162 newly diagnosed prostatic carcinoma patients, 187 patients with benign prostatic hyperplasia (BPH) and 127 controls. The upper limit of normal in controls for PAP was 2.2 micrograms/l and for PSA 5.0 micrograms/l. In the BPH group PAP was raised in 21%, for PSA in 41%. When the cut-off level of PSA was raised to 10.0 micrograms/l, 20% of BPH patients had an increased level. PSA was superior to PAP for the detection of prostatic cancer in all stages. Of the 162 patients with prostatic carcinoma, 88 had localised diseases and 74 had metastatic spread. PSA and PAP levels increased with each advancing clinical stage. PAP was elevated in 35% of the patients with cancer confined to the prostate. PSA in 69%. (PSA level 10.0 micrograms/l: 57%). In those patients with metastatic spread PAP was elevated in 77% compared with 96% for PSA. (PSA level 10.0 micrograms/l: 92%). The combined use of PSA and PAP does not give a greater accuracy in the screening of prostate cancer when compared with the sole use of PSA. PAP was elevated in only 4 patients when PSA was normal. In the BPH group there was no proven effect of micturition, frequency or residual urine on the SPA level. However, in this group infection may cause a rise in the PSA level.