Prostate specific antigen in the diagnosis and treatment of adenocarcinoma of the prostate. IV. Anti-androgen treated patients.

Serum prostate specific antigen was determined (Yang polyclonal radioimmunoassay) in 45 patients after anti-androgen therapy for stage D2, untreated adenocarcinoma of the prostate. Of the patients 9 per cent had undetectable prostate specific antigen levels and 22 per cent were within the normal range (0.0 to 2.5 ng. per ml.), with a mean interval of 2 years since introduction of therapy. Multiple prostate specific antigen values following anti-androgen therapy were available in 36 of 45 patients. The majority of the patients demonstrated an initial, often dramatic decrease in prostate specific antigen levels during the first 6 months after introduction of therapy. After 6 months 21 of 29 patients (72 per cent) had increasing prostate specific antigen levels. Data suggest that serum prostate specific antigen determination 6 months after introduction of therapy is capable of distinguishing patients with a favorable and persisting response to anti-androgen therapy from those in whom a limited response can be expected.