Failure-Free Survival and Radiotherapy in Patients With Newly Diagnosed Nonmetastatic Prostate Cancer Data From Patients in the Control Arm of the STAMPEDE Trial

IMPORTANCE The natural history of patients with newly diagnosed high-risk nonmetastatic (MO) prostate cancer receiving hormone therapy (HT) either alone or with standard-of-care radiotherapy (RT) is not well documented. Furthermore, no clinical trial has assessed the role of RT in patients with node-positive (N+) MO disease. The STAMPEDE Trial includes such individuals, allowing an exploratory multivariate analysis of the impact of radical RT. OBJECTIVE To describe survival and the impact on failure-free survival of RT by nodal involvement in these patients. DESIGN, SETTING, AND PARTICIPANTS Cohort study using data collected for patients allocated to the control arm (standard-of-care only) of the STAMPEDE Trial between October 5, 2005, and May 1, 2014. Outcomes are presented as hazard ratios (HRs) with 95% CIs derived from adjusted Cox models; survival estimates are reported at 2 and 5 years. Participants were high-risk, hormone-naive patients with newly diagnosed MO prostate cancer starting long-term HT for the first time. Radiotherapy is encouraged in this group, but mandated for patients with node-negative (NO) MO disease only since November 2011. EXPOSURES Long-term HT either alone or with RT, as per local standard. Planned RT use was recorded at entry. MAIN OUTCOMES AND MEASURES Failure-free survival (FFS) and overall survival. RESULTS A total of 721 men with newly diagnosed MO disease were included: median age at entry, 66 (interquartile range [IQR], 61-72) years, median (IQR) prostate-specific antigen level of 43 (18-88) ng/mL. There were 40 deaths (31 owing to prostate cancer) with 17 months' median follow-up. Two-year survival was 96%(95% CI, 93%-97%) and 2-year FFS, 77% (95% CI, 73%-81%). Median (IQR) FFS was 63 (26 to not reached) months. Time to FFS was worse in patients with N+ disease (HR, 2.02 [95% CI, 1.46-2.81]) than in those with NO disease. Failure-free survival outcomes favored planned use of RT for patients with both NOMO (HR, 0.33 [95% CI, 0.18-0.61]) and N+MO disease (HR, 0.48 [95% CI, 0.29-0.79]). CONCLUSIONS AND RELEVANCE Survival for men entering the cohort with high-risk MO disease was higher than anticipated at study inception. These nonrandomized data were consistent with previous trials that support routine use of RT with HT in patients with NOMO disease. Additionally, the data suggest that the benefits of RT extend to men with N+MO disease.