Study Raises Questions About Use of High-Dose Radiation For Low-Risk Prostate Cancer

New research confirms that the use of high-dose radiation to treat high-risk prostate cancer lowers the rate of death, but for low-risk patients the research suggests that high-does radiation may not be the best course of action. 

Researchers from the Perelman School of Medicine at the University of Pennsylvania looked at whether high-dose radiation was effective at improving survival rates among men with high-risk, intermediate risk cancer, and low-risk prostate cancers. The study was published online July 16, in the journal JAMA Oncology.

The study tested dose-escalated external-beam radiation therapy (EBRT) for prostate cancer. The retrospective trial compared the effectiveness of EBRT to standard dose EBRT on patients diagnosed from 2004 to 2006 using data from the National Cancer Database. The data included patients treated at community, academic and comprehensive cancer facilities.

Doctors must balance the risks and side effects of radiation therapy against potential benefits. Side effects of EBRT may include irritation of the treated region, fatigue, difficult or painful urination, blood in the urine, abdominal cramping, diarrhea, painful bowel movements, rectal bleeding, rectal leakage, sexual dysfunction and skin reactions.

The study involved more than 42,000 prostate cancer patients, including 12,000 low-risk men, nearly 17,000 intermediate risk men and more than 13,000 high-risk men. Each group was further broken down into two treatment groups, those that received the standard dose of radiation and those that received the dose-escalated radiation.

The dose-escalated EBRT group had improved survival rates in the intermediate-risk and high-risk groups, but not the low-risk group.

For every incremental increase of radiation dose in the intermediate risk group there was a 7.8% reduction in the death rate. Similarly, for every increase of radiation in the high-risk patients there was a 6.3% reduction in the death rate.

For slow growing prostate tumors, known as low-risk, researchers found that using higher dose radiation or EBRT made no difference in survival rates. Low-risk prostate cancer was the most common type of prostate cancer diagnosed in the U.S. in 2014 affecting about 150,000 men.

Researchers say reducing  EBRT doses for patients with low-risk prostate cancer could achieve similar cure rates while avoiding the high risk associated with the side effects of high-doses.

Most doctors believe the dose of radiation should be personalized to the case and risk to offer the lowest chance of toxicity while still maintaining similar survival rates as high-dose treatment.

Researchers say sometimes the best approach for low-risk prostate cancer is active surveillance or “watchful waiting,” where doctors monitor the tumor for changes before beginning radiation treatment.

“These results add to the evidence questioning aggressive local treatment strategies in men with low-risk prostate cancer, but supporting such treatment in men with greater disease severity,” wrote study authors.