ASTRO 2015: Androgen-Deprivation Therapy for 2 Years After Radiotherapy Improves Disease-Free Survival in Patients With Advanced Prostate Cancer
A long-term follow-up of RTOG 9202 indicated that for patients with locally advanced prostate cancer, an additional 24 months of long-term androgen-deprivation therapy after radiation therapy plus short-term androgen-deprivation therapy improved disease-free survival by 60%, compared to patients who only received radiation therapy plus short-term androgen-deprivation therapy, according to research presented by Lawton et al on October 19, 2015, at the American Society for Radiation Oncology’s (ASTRO’s) 57th Annual Meeting in San Antonio, Texas.
Study Details
RTOG 9202 was a randomized, multi-institution study of 1,554 patients with locally advanced prostate cancer to evaluate the potential benefits of long-term androgen-deprivation therapy compared to short-term androgen-deprivation therapy. All patients received radiation therapy of 44 to 46 Gy to the pelvic lymph nodes, and 65 to 70 Gy to the prostate.
Patients were randomized into two groups, with both groups receiving androgen-deprivation therapy for 4 months—both groups of patients received goserelin and flutamide 2 months prior to radiation therapy and for 2 months during radiation therapy. After radiation therapy, the short-term androgen-deprivation therapy group received no additional androgen-deprivation therapy; the long-term androgen-deprivation therapy group received goserelin for 24 months.
Analysis Findings
This study analysis indicated that at 15 years’ follow-up, the long-term androgen-deprivation therapy group continued to show favorable outcomes of disease-free survival compared to the short-term androgen-deprivation therapy group (16% vs 10%, hazard ratio [HR] = 0.72, P < .0001). Additionally, the long-term androgen-deprivation group had less increase in prostate-specific antigen levels, compared to the short-term androgen-deprivation group (cumulative incidence = 45% vs 61%, HR = 0.57, P < .0001).
The incidence of local progression decreased from 13% in the long-term androgen-deprivation group, compared to 23% in the short-term androgen-deprivation group (HR = 0.53, P < .0001). The spread of the cancer to other areas also decreased in the long-term androgen-deprivation group; the distant metastasis rate fell to 17% for the long-term androgen-deprivation group, compared to 26% for the short-term androgen-deprivation group (HR = 0.61, P < .0001). The overall survival rate for the long-term androgen-deprivation group was 30%, compared to 27% for the short-term androgen-deprivation group (HR = 0.90, P = .12).
“Our findings reinforce the benefit of longer androgen-deprivation therapy for patients with locally advanced prostate cancer,” said Colleen A.F. Lawton, MD, FASTRO, and Vice Chair of the Department of Radiation Oncology at the Medical College of Wisconsin. “It is encouraging that 15 years after the initial RTOG 9202 trial, the data continue to emphasize the advantages of long-term androgen-deprivation therapy on disease-specific survival, and thus more patients with advanced prostate cancer should be considered for and may benefit from long-term androgen-deprivation therapy.”
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