Intermittent androgen deprivation therapy for prostate cancer: translating randomized controlled trials into clinical practice

Introduction: Intermittent androgen deprivation therapy (IADT) for prostate cancer involves cycles of androgen deprivation therapy (ADT) with a period between cycles where testosterone is allowed to rise above castrate levels. A number of recent randomized controlled trials (RCTs) have compared survival and health-related quality-of-life (HRQOL) between IADT and continuous ADT (CADT). This review seeks to critically analyze these published trials for their relevance to clinical practice. Materials and methods: Published trials were retrieved from a systematic search of MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials databases using relevant keywords. Recent systematic reviews published on this topic were hand-searched for additional applicable references. The evidence was then synthesized for this review. Results: A number of phase III trials have been recently published. IADT was found to be non-inferior in the primary setting for non-metastatic prostate cancer as well as in treatment of biochemical recurrence following radiotherapy. However, these studies overrepresented low risk patients in whom consideration may be given to deferred ADT rather than early treatment with IADT. In the metastatic prostate cancer setting, IADT was not found to be non-inferior to CADT. In most trials, castration related symptoms improved with IADT and overall HRQOL results were mixed. Little data are available on the effect of IADT on long term complications of ADT. Conclusions: IADT remains a treatment with uncertain outcomes in metastatic prostate cancer and uncertain value over deferring ADT entirely in other prostate cancer clinical states.