Adoption of Intermittent Androgen Deprivation Therapy for Advanced Prostate Cancer: A Population Based Study in American Urology Practice.

INTRODUCTION: In several developed countries intermittent androgen deprivation therapy has been accepted over continuous androgen deprivation therapy for advanced prostate cancer management. To our knowledge its adoption and predictors of use in American urology practice remain unknown. METHODS: Using SEER-Medicare data we identified a cohort of men 66 years old or older who were newly diagnosed with prostate cancer with metastasis or with treated recurrence in whom androgen deprivation therapy was started during 2003 to 2007. We determined intermittent androgen deprivation therapy receipt based on interruptions longer than 3 months between scheduled and actual therapy injections, and physician visits and prostate specific antigen tests during the interruption. Predictors included patient and physician characteristics. We performed logistic regression analysis separately in the metastatic and treated recurrence groups using generalized estimating equations to account for the clustering effect of patients treated by the same physician. RESULTS: Our cohort included 4,281 men, of whom 2,487 with metastasis and 1,794 with treated recurrence received intermittent androgen deprivation therapy. In patients who received intermittent rather than continuous therapy the median duration of therapy was by 6.4 and 9.0 months longer in those with metastasis and treated recurrence, respectively. Each patient group showed significant variation in intermittent therapy use by region (p <0.0001). There was lower intermittent androgen deprivation therapy use in the Eastern and Central regions than in the Mountain and Pacific regions. CONCLUSIONS: Intermittent androgen deprivation therapy has not been widely used in American urology practice. Its adoption shows substantial variation by geographic regions. These regional differences likely reflect uncertainty regarding the efficacy of this therapy among providers as well as differences in patient preferences and involvement in treatment decision making.