ASTRO 2015: Hypofractionated RT effective alternative to treat low-risk prostate cancer

Hypofractionated radiation therapy (RT) has become an intriguing treatment option for cancer thanks to its shortened therapy schedule relative to conventional RT. A recently presented analysis has shown it also largely matches up with conventional RT on cure rates and side effects when used for low-risk prostate cancer.

These findings come from the RTOG 0415 phase III study, and were presented this week at the annual meeting of the American Society for Radiation Oncology (ASTRO) in San Antonio.

“This is the first large-scale, randomized study demonstrating the value of a shorter course of radiation therapy for low-risk prostate cancer patients,” said Howard Sandler, MD, MS, co-author of the study and professor and chair of the department of radiation oncology at Cedars Sinai Medical Center, in a statement.

The researchers, including Sandler, lead author W. Robert Lee, MD, MS, MEd, of Duke University School of Medicine, and colleagues, looked at RTOG 0415 data from April 2006 to December 2009, which compared five-year disease-free survival rates for more than 1,100 men with low-risk prostate cancer from across the U.S. and Canada.

Patients were randomly assigned hypofractionated RT or conventional RT. The former consisted of a 70 Gy treatment administered in 28 fractions over 5.6 weeks, while the latter administered 73.8 Gy in 41 fractions over 8.2 weeks.

After a median follow-up of 5.9 years, the different techniques resulted in similar rates of disease-free survival. Estimates of seven-year disease-free survival pegged the rate at 82 percent for patients treated with hypofractionated RT and 76 percent for those assigned to conventional RT.

Grade 3 late side effects were also similar between groups, according to the authors. For those receiving conventional RT, the rate of gastrointestinal side effects was 3 percent and the rate of genitourinary side effects was 5 percent. For hypofractionated RT, those rates were 5 percent and 6 percent, respectively.