Potential of intermittent hormone therapy for M+ and M0 prostate cancer patients

Abstract

Increasingly animal and clinical studies suggest that intermittent therapy may improve the duration of hormone dependence in patients with prostate cancer. However there remains uncertainty as to optimal duration of treatment and level of prostate-specific antigen (PSA) before treatment is restarted. The aim of this study was to identify risk factors that predict duration of therapy in prostate cancer patients receiving intermittent hormone therapy. Any patients who had achieved PSA complete remission after hormone therapy for metastatic or locally advanced prostate cancer were included in the study. Fifty patients entered on intermittent hormone therapy after achieving a PSA complete remission. In all, 57% of patients remained off treatment at 12 months and the median time for restarting further hormone therapy was 14 months. At 1 y, 95% of patients retreated are progression free and overall 92% are alive at 3 y. There was some evidence that there was a slower progression to require treatment in older M0 patients and those who had been on treatment for more than 9 months. Although M0 patients receiving radiation concurrently after initial hormone down staging had a slower recurrence rate, 53% of M0 patients treated with hormone alone remained off hormones for more than one year. Clearly selection cannot be excluded as a cause for this good survival. However as overall survival in this study is at least as good as that of patients with M0 disease on hormone therapy in the immediate arm of the MRC immediate vs deferred therapy study, there is a case to extend examination of this approach to a randomized trial. This might also include patients failing to achieve PSA complete remission in order to examine the issue of whether continued androgen withdrawal is required in the terminal treatment phase of hormone-resistant patients to keep the hormone sensitive clone under control.