Prostate cancer patients who are treated with a combination of hormone therapy and radiation have a substantially improved chance of survival compared to patients who do not receive radiation, according to interim results of the largest randomized study of its kind presented at the plenary session, November 1, 2010, at the 52nd Annual Meeting of the American Society for Radiation Oncology (ASTRO).

From 1995 to 2005, 1,205 men with high-risk prostate cancer in the United States, the United Kingdom and Canada were randomly selected to receive hormone therapy alone or a combination of hormone therapy and radiation treatment and were followed for at least six years on average. The study was jointly conducted by the National Cancer Institute of Canada, the United Kingdom Medical Research Council and the Southwest Oncology Group in the United States.

Interim results of the study show that the addition of radiation therapy significantly decreased the risk of death among these patients. There were also no increased long-term side effects associated with the treatment. The independent data monitoring committee recommended the release of these results for presentation in view of their importance. The final analysis will be released after further follow-up with the patient group.

"If the figures from the interim analysis are similar to the final analysis, we would expect a 43 percent reduction in the chances of death from prostate cancer in men with this regimen," Malcolm Mason, M.D., lead author of the study and a radiation oncologist at Cardiff University in Cardiff, Wales, United Kingdom, said. "This would translate into a reduction in the chances of deaths from prostate cancer in many thousands of men worldwide."

There is much variation in the treatment for men with localized, high-risk prostate cancer and it is a hotly debated topic. While the number of men treated with combined hormone and radiation therapy has increased in recent years, there are still many patients treated with hormone therapy alone.

This multicenter, randomized trial examined the effects of external beam radiation treatment added to lifelong androgen deprivation therapy for prostate cancer patients who had a high risk of the cancer returning after treatment.

"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," Dr. Mason said. "It shows that the standard treatment for these patients should now be hormone therapy plus radiation."