Impact of the Duration of Adjuvant Hormonal Therapy in Patients With Locally Advanced Prostate Cancer Treated With Radiotherapy: A Secondary Analysis of RTOG 85-31

Purpose Radiation Therapy Oncology Group 85-31 was a randomized trial of androgen suppression for life for patients with locally advanced prostate cancer. However, not all patients continued on the protocol-mandated long-term hormonal therapy despite no evidence of recurrence. We correlated duration of adjuvant hormonal therapy and outcomes among patients who prematurely discontinued hormonal therapy. Patients and Methods The protocol mandated pelvic radiotherapy followed by goserelin given indefinitely or until disease progression. There were 189 analyzable patients. Patients were divided in groups based on the tertile of hormonal therapy duration (HTD) as follows: 1 year, more than 1 year and 5 years, and more than 5 years. Overall survival (OS), disease-free survival (DFS), cause-specific mortality, local failure (LF), and distant metastasis (DM) were studied. Kaplan-Meier estimation and Cox proportional hazards regression model were used for OS and DFS, and Fine and Gray’s regression model was used for the other outcomes. Results The median follow-up for surviving patients is 9.6 years. The median duration of adjuvant hormonal therapy was 2.2 years. The HTD more than 5 years group is significantly associated with an improved survival and DFS and fewer DMs than other HTD groups. After adjustment for age, radical prostatectomy, nodal status, Gleason score, and stage variables, the HTD more than 5 years group remains significantly associated with better OS and DFS than other HTD groups. Conclusion In this hypothesis-generating analysis, prolonged HTD of more than 5 years seems significantly associated with improvements in most outcomes. Given these data, decreasing HTD to 5 years may have a detrimental effect on patients with locally advanced prostate cancer. Only a randomized trial will conclusively clarify this issue.