Two years of anti-androgen therapy consisting of bicalutamide 150 mg daily during and after salvage radiotherapy in patients with localized prostate cancer significantly improved long-term overall survival and reduced incidence of metastatic disease and prostate cancer-related death.1
Because previous research suggested that anti-androgen therapy may improve prostate cancer control outcomes after prostatectomy when used in combination with salvage radiotherapy, researchers sought to evaluate the use of bicalutamide during and after salvage radiotherapy following prostatectomy in patients with elevated prostate-specific antigen (PSA).
For the double-blind, phase 3 trial, researchers enrolled 761 post-prostatectomy patients with pT3pN0 or pT2pN0 and positive margins who had or developed elevated PSA levels from 0.2 to 4.0 ng/mL. Participants were randomly assigned to receive 64.8 Gy in 36 fractions plus placebo or bicalutamide 150 mg daily for 24 months during and after radiation.
Results showed that at a median follow-up of 12.6 years, the 10-year overall survival rate was 82% for bicalutamide compared with 78% for placebo (HR, 0.75; 95% CI, 0.58 – 0.98; P < .036).
Researchers found that the 12-year cumulative incidence of metastatic prostate cancer was 14% in the bicalutamide arm vs 23% in the placebo arm (P < .001) and the 12-year incidence of prostate cancer deaths were 2.3% and 7.5%, respectively (P < .001).
In terms of safety, late grade 3 and 4 toxicities were similar between the 2 treatment arms. Grade 3 to 4 genitourinary toxicities occurred in 7.0% of patients in the bicalutamide arm compared with 6.7% in the placebo group, and gastrointestinal toxicities occurred in 2.7% and 1.6% of patients, respectively. Of note, there was a significant difference in the rate of gynecomastia between the 2 arms (70% with bicalutamide vs 11% with placebo).
- Shipley WU, Pugh SL, Lukka HR, et al. NRG Oncology/RTOG 9601, a phase III trial in prostate cancer patients: anti-androgen therapy (AAT) with bicalutamide during and after salvage radiation therapy (RT) following radical prostatectomy (RP) and an elevated PSA. J Clin Oncol. 2016; 34 (suppl 2S; abstr 3).