Objectives: A case report is presented of 2 patients whose levels of serum prostate-specific antigen (PSA) improved after the withdrawal of a steroidal antiandrogen.
Methods: Two cases with prostate cancer had been treated with surgical castration and the steroidal antiandrogen chlormadinone acetate (CMA), and, on disease progression, the administration of CMA was terminated.
Results: Following withdrawal of CMA, a fall in PSA levels and remarkable clinical improvement were observed in both cases. One patient revealed a decrease and the other an increase in serum prostate acid phosphatase after the discontinuation of CMA. Serum levels of testosterone, prolactin, dehydroepiandrosterone, dehydroepiandrosterone sulfate, and androstenedione were not significantly elevated after CMA withdrawal.
Conclusions: Withdrawal of the steroidal antiandrogen CMA resulted in a decline in PSA levels and clinical improvement in prostate cancer patients with disease progression. Changes in testosterone, prolactin, or adrenal androgens were not a cause of the antiandrogen withdrawal syndrome.