Long-term survival update of the Scandinavian Prostate Cancer Group 6 study: Bicalutamide 150 mg daily versus placebo in hormone-naïve, non-metastatic prostate cancer.

Abstract

2 Background: The optimal timing of endocrine therapy in non-metastatic prostate cancer (PCa) is not clear. There is a need for more data from randomized trials. Methods: A randomized, double-blind, parallel-group trial comparing bicalutamide 150 mg once daily with placebo in addition to standard of care in patients with hormone-naïve, non-metastatic PCa. Kaplain-Meier analysis was used to estimate overall survival (OS) and multivariate Cox proportional hazard model was performed to analyse time-to-event (death). Results: 1,218 patients were included into the SPCG-6 study, 607 patients were randomised to bicalutamide and 611 patients to placebo. The majority (81.4%) were managed on watchful waiting. After median 14.6 years follow-up, 866 (71.1%) patients died, 428 (70.5%) in the bicalutamide arm and 438 (71.7%) in the placebo arm, p=0.87. In patients with localised disease (cT1-2, N0/Nx) survival favoured randomisation to the placebo arm (HR=1.19 (95% CI: 1.00-1.43), p=0.056). Bicalutamide significantly improved OS and reduced the risk of death by 23% relative to the placebo arm in patient with locally advanced disease (cT3-4, any N; or any cT, N+) with a median survival difference of 1.8 years (HR=0.77 (95% CI: 0.63-0.94, p=0.01). The survival benefit of bicalutamide in patients with locally advanced PCa was present throughout the study period. In multivariate Cox proportional hazard model OS was dependent on age (HR 1.55 (95% CI:1.20-1.85)), baseline PSA (localised PCa HR for 2 x increase in PSA 1.09 (95% CI:1.02-1.16), locally advanced PCa HR 1.23 (95% CI:1.14-1.33)), WHO histological grade (moderate vs. well HR 1.27 (95% CI:1.08-1.49), poor vs. well HR 1.92 (95% CI:1.51-2.45)), and randomisation to placebo in locally advanced disease (HR=0.76 (95% CI: 0.61-0.95)). Conclusions: The addition of early bicalutamide to standard of care resulted in a significant OS benefit in patients with locally advanced PCa, whereas patients with localised PCa derived no survival benefit from early bicalutamide. The survival benefit of bicalutamide therapy increased with higher baseline PSA. Clinical trial information: NCT00672282.