Results of the study support that hypothesis. Patients who received the standard dose radiotherapy were significantly more likely to go on to salvage therapy, compared with patients in the dose-escalation arm.
Dr. Michalski and his associated reported on the randomized NRG Oncology/RTOG 0126 clinical trial, which included 1,532 patients with intermediate-risk cancer enrolled between March 2002 and August 2008 at one of 104 North American sites.
In the trial, patients with intermediate-risk prostate cancer were randomized to receive three-dimensional conformal radiation therapy or intensity-modulated radiation therapy to 79.2 Gy in 44 fractions or 70.2 Gy in 39 fractions, the study said.
With a median follow-up of 8.4 years for 1,499 patients, there was no difference in overall survival between arms, study results show. The 8-year rates of overall survival were 76% for dose-escalated radiotherapy and 75% for standard radiotherapy (hazard ratio, 1.00; 95% confidence interval, 0.83-1.20; P = .98).
Otherwise, patients in the dose-escalated radiotherapy arm had significantly lower rates of distant metastases (4% vs. 6%; P = 0.05), and lower rates of biochemical failure rates at both 5 and 8 years, investigators said.