Stereotactic radiation therapy safe, efficacious in low-risk PCa

Higher doses of stereotactic radiation therapy requiring fewer treatments are safe and effective in patients with low- to intermediate-risk prostate cancer, say the authors of a multicenter study.

Results of the trial, which were published in the Journal of Clinical Oncology (2011; 29:2020-6), showed that stereotactic body radiation therapy was effective in treating patients with localized prostate cancer in five 30-minute sessions every other day over 2 weeks, compared with the typical protocol of 42 to 45 daily treatments administered over 8 to 9 weeks.

"We were trying to develop a fast, convenient, outpatient, noninvasive treatment," said senior author Robert Timmerman, MD, of the University of Texas Southwestern Medical Center, Dallas. "In the low-risk population, there are a lot of good options, but none of them are altogether convenient. The most convenient treatment would finish quickly without the need for a prolonged recovery.

"We’re trying to kill the prostate cancer, but without injuring the urethra, the bladder, or the rectum," he added. "Each treatment had to be very potent in order to get the full radiation effect in only five treatments."

To avoid injury to healthy tissue, researchers used beams of radiation that were just millimeters larger than the target itself. That narrow scope helped avoid consequences such as rectal injury, erectile dysfunction, and difficulty urinating, the researchers said.In the current clinical trial, researchers tested escalating doses for safety levels in 45 patients enrolled from November 2006 to May 2009. In a 90-day follow-up procedure, they looked at how much injury occurred in adjacent areas, including the rectum or urethra, and any changes to the patients’ quality of life.

"There were a few more complications associated with higher doses, but they were fairly predictable and rarely severe," said co-author Yair Lotan, MD. "By giving these higher doses, we might be able to kill more resistant tumors with shorter treatments."

Study authors also included researchers from the University of Minnesota, Minneapolis and Prairie Lakes Hospital, Watertown, SD.