Patients with prostate cancer who are treated with radiation therapy in addition to hormone therapy have significantly higher chances of survival than patients treated with hormone therapy alone, according to a study that will be presented Nov. 1 at the annual meeting of the American Society of Radiation Oncology (ASTRO) in San Diego.

While treatment for localized, high-risk prostate cancer using radiotherapy as well as hormone therapy has increased in recent years, treatment regimens for the disease vary substantially, and many men receive androgen deprivation therapy (ADT) without undergoing radiotherapy. Researchers at the National Cancer Institute of Canada, the United Kingdom Medical Research Council and Southwest Oncology Group in the U.S. sought to measure the effect of radiation therapy on overall survival in patients with locally advanced prostate cancer who were on lifelong ADT.

The multi-center study included 1,205 patients who were randomly selected to be treated with either lifelong ADT and radiotherapy or ADT alone. The mean follow-up time for the ongoing study is six years.

One hundred fifty patients have died as a result of the disease, 51 from the ADT plus radiotherapy group and 89 hormone therapy patients. The 10-year disease-specific death rates observed in the study were 15 percent for ADT with radiotherapy and 23 percent for ADT alone. The reduced death rate for ADT plus radiotherapy patients was statistically significant.

"This study is practice changing as it highlights the importance of radiation in the treatment of high-risk prostate cancer patients and clearly demonstrates its benefits," Malcolm Mason, MD, lead author of the study and a radiation oncologist at Cardiff University in Cardiff, Wales, United Kingdom, wrote. "It shows that the standard treatment for these patients should now be hormone therapy plus radiation."