Prostate Cancer Can Be Treated With Higher Radiation Doses, Fewer Treatments

Results from a new study have proven that higher intensity radiation doses requiring fewer treatments are safe and effective for patients with low-to-intermediate risk prostate cancer.

UT Southwestern Medical Center researchers have found that stereotactic body radiation therapy (SBRT), which delivers ultra-precise radiation, is effective in treating patients with localized prostate cancer in five 30-minute sessions every other day over a period of two weeks.

Normal procedure is to administer 42 to 45 daily treatments over a period of eight to nine weeks.

In a multicenter clinical trial, UT Southwestern Medical Center researchers have found that higher doses of stereotactic radiation therapy requiring fewer treatments are safe and effective for patients with low-to-intermediate-risk prostate cancer.

“We were trying to develop a fast, convenient, outpatient, non-invasive treatment,” said Dr. Robert Timmerman, vice chairman of radiation oncology and professor of neurological surgery and senior author of the study, in a press release. “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.”

SBRT has also been used to treat patients with lung, liver and brain cancers.  The current study has proven that high dosage treatments can work in a moving target like the prostate, which shifts considerably due to normal bladder and bowel filling.

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

In order to avoid damaging the healthy tissue, researchers used radiation beams that were only millimeters larger than the target.  This way, they were able to minimize the risk of rectal injury, impotence or difficulty urinating.

Prostate cancer is the most common cancer in men.  About 200,000 cases are diagnosed per year in the United States.  Half of those undergo radiation therapy, but not everyone is cured because some tumors are resistant to radiation.

In the study, researchers tested escalating doses of radiation for safety levels in 45 patients over from November 2006 to May 2009.  They monitored for any injuries in adjacent areas, such as the rectum or urethra, and changes in the patients quality of life. 

“There were a few more complications associated with higher doses, but they were fairly predictable and rarely severe,” said Dr. Yair Lotan, associate professor of urology and a co-author of the study. “By giving these higher doses, we might be able to kill more resistant tumors with shorter treatments.”

The study was published in the Journal of Clinical Oncology.