A shorter, five-week course of radiation treatment that delivers higher doses of radiation in fewer sessions, known as hypofractionation, appears to be just as effective and as safe in reducing the risk of prostate cancer from returning as standard radiation therapy, yet is delivered in two-and-a-half weeks less time, according to interim results of a randomized study presented at the 51st Annual Meeting of the American Society for Radiation Oncology (ASTRO).

"The study shows that hypofractionated radiation could potentially be used in place of standard radiation therapy for intermediate and high risk prostate cancer patients, but the results are still preliminary," Alan Pollack, M.D., lead author of the study and a radiation oncologist at the University of Miami Miller School of Medicine in Miami, Fla., said. "We are excited about this research because the shorter course of treatment is more convenient, would reduce health care costs and appears just as effective."

Patients in the study received a special type of external beam radiation called intensity modulated radiation therapy, or IMRT, that allows radiation to be more exactly shaped to fit the prostate. Using IMRT, the amount of radiation received by healthy tissues near the tumor are reduced. This has allowed the investigators to give higher doses per day without increasing toxicity significantly.

The study involved 303 men with intermediate and high risk prostate cancer who were randomized to receive hypofractionated IMRT for 26 treatments (five weeks of daily radiation therapy) or standard IMRT for 38 treatments (seven-and-a-half weeks of daily treatments) to the prostate and surrounding area. High-risk patients also received treatment to the pelvic lymph nodes.

In addition to radiation treatment, 34 of the 200 intermediate risk patients received short- term hormone therapy for a median of four months, while 102 of 103 high risk patients in the hypofractionated group received long-term hormone therapy for 25 months. The study shows that 39 months after treatment, there is no significant difference in cancer recurrence between patients who underwent hypofractionated IMRT (14 percent) and standard IMRT (19 percent). There is also no difference in genitourinary and gastrointestinal side effects between the two groups.

"Although these are significant findings, longer follow-up is needed and a final analysis is planned for 2011," Dr. Pollack said. "Other clinical trials are exploring hypofractionation and I encourage men with prostate cancer interested in shorter treatments to talk to their radiation oncologist about joining a study."