Current experience with radioimmunoassay techniques for prostatic acid phosphatase.

Data are presented demonstrating that radioimmunoassay techniques for measurement of serum prostatic acid phosphatase are more sensitive than enzymatic methods in the detection of all stages of prostatic cancer. The possibility of using a solid phase RIA technique to screen for prostatic cancer is considered. Sixty-three hundred and twenty men over age 45 entering a clinical laboratory for any indication were evaluated using the RIA test for PAP. In this group 444 (7%) had elevated test values. Clinical recall and urologic review of the patients with elevated test results yielded 67 who were suspect for prostatic cancer, of whom 59 (88%) were confirmed by prostatic needle biopsy. These data suggest that the RIA for prostatic acid phosphatase as an isolated clinical procedure is not sufficiently specific to be used for screening due to the large number of false-positive results. However, the RIA-PAP test in combination with a follow-up urologic examination is quite specific and deserves further consideration as a screening method for prostatic malignancy.