Adding Antiandrogen Therapy to Radiation Improves Survival

Arising PSA following a prostatectomy is called biochemical recurrence, and can be a warning sign of recurrent cancer. More than 30% of men have biochemical recurrence after their prostates are removed. Often, patients with biochemical recurrence receive salvage radiation therapy to prevent the development of a tumor in the pelvis where the prostate had been, or elsewhere if the cancer has spread.

The Harvard study began in 1998 and enrolled 760 patients who had biochemical recurrence after having their prostate glands removed for localized cancer. Patients in the study underwent radiation therapy for 7 weeks and were randomly assigned to receive antiandrogen therapy (24 months of bicalutamide at a dose of 150 mg daily) or a placebo. Antiandrogens are drugs that stop male sex hormones from working.

The researchers followed the patients for an average of 12 subsequent years and found that patients who took daily bicalutamide had higher rates of longterm overall survival and lower incidences of metastatic prostate cancer and death from prostate cancer. The overall survival rate in the bicalutamide group was 76%, compared to 71% in the placebo group. The incidence of metastatic prostate cancer was 14.5% in the bicalutamide group, compared to 23% in the placebo group. The incidence of death from prostate cancer was 5.8% in the bicalutamide group, compared to 13.5% in the placebo group.

In recent years, drugs called gonadotropin-releasing hormone (GnRH) agonists have largely replaced bicalutamide because they are more potent against prostate cancer. New studies are underway examining the efficacy of GnRH agonists in conjunction with radiation therapy.

The study was conducted by the NRG Oncology Radiation Therapy Oncology Group.