Salvage radiation treatment combined with daily anti-androgen therapy for men with prostate cancer (PCa) that recurs or persists following radical prostatectomy improves long-term overall survival compared with the use of salvage radiation treatment alone, according to a new study.
The dual treatment also results in a lower incidence of metastatic disease and PCa-specific death.
In a randomized, double-blind study of 760 PCa patients who underwent salvage radiation therapy, researchers found that patients who also received 24 months of daily bicalutamide had a statistically significant 23% lower risk of death at 12 years compared with patients who received daily placebo.
The bicalutamide and placebo groups included 384 and 376 men, respectively. Bicalutamide recipients took a 150-mg tablet of the medication daily. In both groups, 258 patients completed therapy as planned. Surviving patients had a median follow-up of 13 years. The actuarial survival rate at 12 years was 76.3% in the bicalutamide group versus 71.3% in the placebo arm, William U. Shipley, MD, of Massachusetts General Hospital in Boston, and colleagues reported study findings in The New England Journal of Medicine (2017;376:417-428). The cumulative incidence of metastatic PCa at 12 years was 14.5% in the bicalutamide group versus 23.0% in the placebo arm. The 12-year incidence of cancer-specific death was 5.8% in the bicalutamide group compared with 13.4% among placebo recipients. All of these between-group differences were statistically significant.
The 2 groups had a similar incidence of late adverse events associated with radiation therapy, according to the investigators.
Since the trial was designed, gonadotropin-releasing hormone (GnRH) agonists have superseded bicalutamide as the first-choice hormonal therapy with radiation therapy, the researchers pointed out. Randomized trials involving patients with non-metastatic disease have demonstrated that high-dose bicalutamide and GnRH agonists have similar systemic anti-cancer efficacy, they stated. “As such, our trial presents proof of principal that the addition of hormone-based therapy to salvage radiation therapy is associated with significant and clinically important lower rates of prostate-cancer metastases and death,” they wrote.
Given the lower rate of death and the lack of evidence of higher other-cause mortality in the bicalutamide recipients versus the placebo group, Dr Shipley and his colleagues calculated that 20 patients would need to be treated with bicalutamide to avoid 1 death over a 12-year period.
To be eligible for study, patients were required to have a detectable PSA level of 0.2 to 4.0 ng/mL at least 8 weeks after surgery and a Karnofsky performance-status score of 80 or higher. Patients also could not have previously received chemotherapy or radiation therapy for PCa. In all patients, abdominal and pelvic computed tomographic and bone scans showed no evidence of metastatic disease.