Intermittent androgen castration: A biological reality during intermittent treatment in metastatic prostate cancer?

Introduction: To assess the effects of intermittent maximal androgen blockade ( IMAB) on testosterone ( T) levels during on- and off-treatment periods. Materials and Methods: A total of 51 patients with metastatic prostate cancer underwent a 6- months period of continuous maximal androgen blockade ( MAB) consisting of leuprorelin (3.75 mg at monthly intervals) plus flutamide (250 mg t.i.d.) followed by IMAB. During each cycle, the cut-off prostate-specific antigen (PSA) levels to stop and resume treatment were 4 and 10 ng/ml, respectively. IMAB continued until progression under treatment occurred. Monthly PSA and T measurements were performed in central laboratories. Results: From the 51 patients included ( mean age 67.6 years), 27, 16, 12, 8 and 5 underwent a second, third, fourth, fifth and sixth cycle, respectively (mean follow up: 17 months). Before treatment, 4 patients had a T lower than normal laboratory value but these recovered all to a normal T value at the end of the first cycle. During the 6 cycles, only 8 patients did not recover a normal T at least once during the off- treatment periods ( OTP). The mean T values at the end of each OTP did not change during these 6 cycles ( Anova test, p = 0.621) with a mean stable recovery delay of 32 - 43 days ( Anova test, p = 0.722). Conclusion: IMAB protocol with an initial 6- month treatment period can result in an intermittent castration with the recovery of normal T levels in most patients during six consecutive cycles of treatment.