The addition of six months of androgen suppression therapy to radiation therapy improves survival of patients with clinically localized prostate cancer, according to an article in the August 18th issue of the Journal of the American Medical Association.

“Combining three years of androgen suppression therapy with 70 Gy radiation has been shown to improve survival rates for patients with locally advanced prostate cancer,” the authors wrote. “However, the toxicity of long-term androgen suppression therapy can be significant, particularly in elderly patients.”

Anthony V. D’Amico, MD, PhD, and his American colleagues assessed the survival benefit of three-dimensional conformal radiation therapy alone or in combination with six months of hormone therapy in patients with clinically localized prostate cancer. The 206 patients were randomized to receive 70 Gy radiation alone (n=104) or radiation therapy in combination with six months of androgen suppression therapy (n = 102) from December 1, 1995 to April 15, 2001.

The patients included those with a prostate specific antigen level of at least 10 ng/mL, a Gleason score of at least 7, or radiographic evidence of disease outside the prostate. Follow-up visits were performed at the end of radiation treatment every three months for two years, every six months for an additional three years, and then annually until death or January 15, 2004, the end of the study.

“After a median follow-up of 4.52 years, patients randomized to receive three-dimensional conformal radiation therapy plus androgen suppression therapy had significantly higher survival, lower prostate cancer-specific mortality, and higher survival free of salvage androgen suppression therapy,” the authors found.

Standardized estimates of five-year survival rates were 88 percent in the combination therapy group versus 78 percent in the radiation only group. Rates of survival free of salvage androgen suppression therapy at five years were 82 percent in the combination group versus 57 percent in the radiation only group.

The researchers noted there were 6 deaths due to prostate cancer and 17 from other causes for patients receiving radiation therapy. For patients receiving combination therapy, no deaths occurred due to prostate cancer and 12 were from other causes.

“Given that many men treated for prostate cancer are often older and that androgen suppression therapy use of more than one year has been shown to cause osteopenia, impairment of memory, attention and executive functions, and prolongation of the QT interval, in addition to anemia, muscle loss in exchange for body fat, hot flashes, and impotence, minimizing these effects by decreasing androgen suppression therapy duration could profoundly impact a patient’s quality of life. Therefore, the clinically significant implication of our study is that a six-month course of androgen suppression therapy in patients receiving radiation therapy who have clinically localized prostate cancer may be sufficient to reduce the risk of death,” the authors concluded.