Souhami, L. et al. Impact of the duration of adjuvant hormonal therapy in patients with locally advanced prostate cancer treated with radiotherapy: a secondary analysis of RTOG 8531. J. Clin. Oncol. 27, 2137–2143 (2009).

Secondary analysis of RTOG 85-31, a randomized phase III study comparing pelvic radiotherapy alone with pelvic radiotherapy plus hormonal therapy for life in patients with locally advanced prostate cancer, has indicated that early discontinuation of hormonal therapy could adversely affect survival. “When we looked at the duration of hormonal therapy in the group that was supposed to receive it for life, we noticed that the median duration was 3.58 years. This triggered an interest in trying to establish whether this had an impact on survival and disease recurrence outcomes,” explains lead author Luis Souhami from McGill University Health Center in Montreal, Canada.

...patients who persisted with goserelin therapy for more than 5 years had better overall survival...

The original trial protocol mandated pelvic radiotherapy followed by goserelin indefinitely or until disease progression. Souhami and colleagues analyzed data from 189 patients who failed to adhere to this protocol. These men were divided into three groups on the basis of duration of hormonal therapy: up to 1 year, 1–5 years, or more than 5 years. After adjusting for factors such as age, nodal status, Gleason score, radical prostatectomy and stage variables, patients who persisted with goserelin therapy for more than 5 years had better overall survival than those who ceased treatment before the 5 year mark. “There was an improvement in all outcomes studied, including disease-free survival, in those patients receiving hormonal therapy for 5 years or longer,” notes Souhami.

A randomized noninferiority trial of hormonal therapy for 6 months or 36 months indicated that the shorter course of treatment was detrimental to patients with high-risk prostate cancer. Early publication of results of EORTC 22961, for which 970 men were randomized, was recommended by the data monitoring committee when interim analysis showed futility of the short-course regimen. “Our results are provocative, but this secondary analysis is a hypothesis-generating exercise; conclusively defining the optimal duration of hormonal therapy in the adjuvant setting for patients with high-risk disease would require a prospective phase III study,” concludes Souhami.