Objective: To assess the efficacy of low dose ketoconazole therapy for Chinese patients with castration resistant prostate cancer (CRPC) and explore possible prognosis factors.
Methods: From August 2006 to August 2011, 71 patients with CRPC were analyzed retrospectively, who received oral ketoconazole 200 mg, three times a day with prednisone 5 mg, twice a day. Prostate specific antigen (PSA) response rate was defined as the percentage of patients with PSA decline ≥ 50% compared to baseline PSA level during low dose ketoconazole therapy. Multivariate Logistic regression analysis and receiver operating characteristic curve were used to assess the prognostic factors and their accuracy.
Results: The mean initial serum PSA level was (205 ± 38) ng/ml for these patients with mean age (69 ± 1) years old. After first androgen deprivation therapy failure, the prostate cancer progressed into castration resistant stage. The baseline PSA was (93 ± 24) ng/ml and the baseline serum testosterone was (0.13 ± 0.02) ng/ml. During the low dose ketoconazole therapy, 31 patients (43.7%) had PSA decrease and 22 cases (31.0%) were effective with PSA decline more than 50%. PSA doubling time and baseline serum testosterone were positive correlation with PSA response rate by multivariate Logistic regression analysis. Patients with PSA doubling time of ≥ 3.0 months had a PSA response rate of 64.3% and the PSA response rate in those with < 3.0 months decreased to 22.8%, hazard rate (HR) = 0.149 (95% confidence interval [CI] 0.029 - 0.766), P = 0.023, area under the curve (AUC) = 0.707. The PSA response rate for patients with baseline serum testosterone ≥ 0.1 and < 0.1 µg/L were 55.6% and 5.7%, respectively, HR = 0.068 (95%CI 0.012 - 0.380), P = 0.002, AUC = 0.749. The common adverse reactions included liver dysfunction (17.9%), renal dysfunction (16.4%), fatigue (11.9%), nausea (6.0%) and anorexia (4.5%) and so on.
Conclusions: Low dose ketoconazole therapy was a moderate, low toxicity hormonal therapy option for patients with CRPC. PSA doubling time ≥ 3 months and baseline serum testosterone ≥ 0.1 µg/L were predictors of desired effect for low dose ketoconazole therapy.