[Preventive effect of chlormadinone acetate on flare-up phenomenon in advanced prostate cancer administered with a luteinizing hormone-releasing hormone analogue].

To investigate whether chlormadinone acetate (CMA) could prevent the flare-up phenomenon induced by a luteinizing hormone-releasing hormone analogue (LH-RHa), we treated 4 cases of stage C and 17 cases of stage D prostate cancer with CMA for 4 weeks and CMA plus monthly injection of LH-RHa for following 24 weeks. Serum LH, testosterone, and prostate-specific antigen (PSA) levels were closely monitored before and 3 days, 1-, 2-, and 4-weeks after LH-RHa injection. Subjective and objective responses were also investigated. Serum LH and testosterone levels significantly elevated 3 days after the initial injection of LH-RHa. However, they resumed 1 week after LH-RHa injection with fluctuation under the normal range. Out of 21 cases, 3 cases (14%) consisting of 2 poorly and 1 moderately differentiated adenocarcinoma showed increased serum PSA levels 1 week after LH-RHa injection in spite of suppressed serum testosterone levels. The objective response of these 2 poorly differentiated cases was progressive disease at 24 weeks. No cases indicated worsening of clinical symptoms concerning flare-up phenomenon. CMA seemed to be capable of preventing flare-up phenomenon in advanced prostate cancer.