Significance of PSA and PAP in patients with or without prostatic cancer

Coupled prostate-specific antigen (PSA) and prostatic acid phosphatase (PAP) measurements (using the radioimmunoassay method) were carried out on 220 controls, 33 patients with prostatic hyperplasia, and 71 with carcinoma. The mean PSA value was 3.70 +/- 3.31 ng in the controls. A level of 10 ng was adopted as the upper limit of normal. Four of the eight cases of prostatic hyperplasia with a high PSA level (between 10 and 25 ng) underwent surgery. Histological tests confirmed benign hyperplasia. In the localized cancers, the PSA level was normal. In the metastatic cancers, PSA proved to be more sensitive than PAP. Thus, PSA is of little use in the early diagnosis of cancer; its systematic measurement as a means of cancer screening for the general public may even be misleading.