Intermittent androgen suppression for prostate cancer.

Although androgen deprivation therapy (ADT) has been a cornerstone of the management of prostate cancer for more than 50 years, controversy remains regarding its optimum application. Intermittent androgen suppression (IAS) has been researched since the mid-1980s as a way of reducing the adverse effects and cost of continuous androgen suppression. With preclinical evidence suggesting a potential benefit in terms of time to androgen independence, IAS has been the focus of a number of clinical phase II and III trials. Overall, these trials suggest that IAS is neither inferior nor superior to continuous androgen suppression, with respect to time to castration resistance and cancer-specific survival, but has significant advantages in terms of adverse effects, quality of life and cost. A number of unresolved questions remain, however, including how to select patients for therapy, the optimum duration of therapy, when to restart therapy after the off cycle, and how to define progression to castration-resistant disease. Landmark randomized clinical trials comparing IAS to continuous androgen suppression are in progress and will hopefully answer many of these questions. In future, the use of second-line drugs in the off-treatment phase holds potential for delaying disease progression in men on IAS. At present, men with advanced disease who are deemed candidates for ADT should be informed of IAS as a treatment option, considered experimental from an informed consent point of view, but promising based on current evidence.