A large Phase III Radiation Therapy Oncology Group (RTOG) study reports that men with intermediate-risk, early-stage prostate cancer who undergo short-term hormone therapy before and during moderate-dose radiation therapy live longer and are less likely to experience a recurrence, compared with men who receive the same radiation therapy alone. However, the addition of short-term hormone therapy does not appear to confer the same benefit to men with low-risk, early-stage disease.

The study was presented at the 2010 Genitourinary Cancers Symposium which is co-sponsored by the American Society for Clinical Oncology (ASCO), the American Society for Radiation Oncology (ASTRO) and the Society of Urologic Oncology (SUO).

"These data indicate that men with early-stage prostate cancer who have intermediate-risk disease stand to benefit from the addition of four months of hormone therapy prior to and during radiation therapy," said study author Christopher Jones, M.D., a partner of Radiological Associates of Sacramento who serves as their principal investigator for RTOG.

Hormone therapy is often used to slow prostate cancer growth in men with advanced disease, and its use in men with earlier-stage cancer is being investigated. In this study, researchers compared overall survival and recurrence (as determined by repeat prostate biopsies) in 987 men with localized prostate cancer who had a PSA of 20 or less and who received four months of hormone therapy (HRT), starting two months before radiation therapy, and 992 similar men who received radiation therapy alone.

After a median follow-up of 8.4 years in the HRT group and 8.1 years in the radiation-only group, the study met its primary endpoint by documenting that 51 percent of the patients who received HRT were still alive at 12 years, compared with 46 percent of those who received radiation alone. The survival benefit of hormone therapy appeared to be greatest among men with intermediate-risk disease (a Gleason Score of 7, or a Gleason Score of 6 or less with either a PSA between 10 and 20 or clinical T2b disease); 54 percent of patients in this study had this stage of disease. Investigators found that men with low-risk disease (35 percent of participants) did not benefit from the addition of hormone therapy.

At two years following treatment, 843 men underwent repeat prostate biopsies. In those treated with hormones and radiation, 78 percent of these biopsies showed no cancer, versus 60 percent in the radiation-only group. Hormone therapy was well tolerated by the majority of patients, and analyses are continuing to examine potential late side effects.

The authors added that recent advances in radiotherapy technology have led to the administration of higher radiation doses than those given to men in this study, so it remains uncertain whether hormone therapy would provide the same or greater benefit to current patients. To answer this question, RTOG recently opened a new trial (RTOG 0815) examining the role of hormone therapy combined with modern radiotherapy techniques for the same patient population - men with intermediate-risk, early-stage prostate cancer.