Survival benefit associated with adjuvant androgen deprivation therapy combined with radiotherapy for high- and low-risk patients with nonmetastatic prostate cancer

Background: The use of adjuvant androgen deprivation therapy (ADT) combined with radiotherapy has become common in low-risk patients, although clinical trials have focused primarily on high-risk patients. This study examines the effectiveness of adjuvant ADT combined with radiotherapy for a wide range of patients treated in the 1990s. Methods and Materials: Prostate cancer survival was examined in a population based cohort of 31,643 patients aged 65 to 85 years who were diagnosed with nonmetastatic prostate cancer and treated with external beam radiotherapy and/or brachytherapy. Instrumental variable analysis methods were used to control for selection bias. Results: Patients with stage T3/T4 disease who received adjuvant ADT experienced improved 5-year and 8-year survival. No survival advantage was observed for men with T1/T2 disease during this interval. Conclusion: High-risk patients who receive primary radiotherapy have benefited from adjuvant ADT, whereas low-risk patients with disease confined to the prostate have not yet benefited from adjuvant therapy within the first 8 years after treatment. These findings are consistent with practice guidelines, which recommend adjuvant ADT for patients with high-risk disease.