Duration of testosterone suppression and the risk of death from prostate cancer in men treated using radiation and 6 months of hormone therapy

BACKGROUND. The authors evaluated whether the duration of androgen suppression (AS) after the completion of hormone therapy (HT) was associated with the risk of prostate cancer-specific mortality (PCSM) and all-cause mortality (ACM). METHODS. The study cohort was comprised of 220 men who received radiation therapy (RT) and 6 months of HT for prostate cancer between 1996 and 2005. The duration of AS was defined as the time to return to the baseline testosterone level after the completion of HT. Grays and Cox regression analyses were used to evaluate whether the duration of AS after the completion of HT was associated with the time to PCSM and ACM, respectively, after adjusting for known prognostic factors. RESULTS. An increasing duration of AS was associated with a decreased risk of PCSM (adjusted hazards ratio [HR], 0.89; P = .003) and ACM (HR, 0.94; P = .007). Men who had prostate cancer with Gleason scores from 8 to 10 had significantly lower cumulative incidence estimates of PCSM (P = .04) if the duration of AS plus the length of HT administration was >= 2 years compared with <2 years. After a median follow-up of 6.1 years, the respective 5-year estimates were 0% and 38%. CONCLUSIONS. The duration of AS after 6 months of HT was associated with the risk of PCSM and ACM. This duration could be used to identify men who have prostate cancer with Gleason scores from 8 to 10 in whom 6 months of HT produces long-term testosterone suppression, which may provide the cancer-specific survival benefit observed with long-term HT.