Dose-Escalated Radiation Therapy for Intermediate-Risk Prostate Cancer
Posted: Thursday, June 28, 2018
In a randomized clinical trial involving approximately 1,500 men with intermediate-risk prostate cancer, dose-escalated radiation therapy was associated with significant improvements in biochemical control and distant metastases—but not in the primary endpoint of overall survival. Although higher doses of radiation caused more late toxic effects in this study population, this therapy was associated with lower rates of salvage therapy. Jeff M. Michalski, MD, MBA, of Washington University School of Medicine in St. Louis, and colleagues published these results in JAMA Oncology.
The 8-year overall survival rate (median follow-up, 8.4 years) was 76% for the high-dose group (79.2 Gy; n = 751) versus 75% for the standard-dose group (70.2 Gy; n = 748; P = .98). However, patients receiving dose-escalated therapy experienced more late toxic effects and needed less salvage local or systemic therapy than those who received the standard dose. Specifically, the 5-year rates of late grade 2 or greater gastrointestinal and/or genitourinary toxic effects were 21% and 12% with 79.2 Gy and 15% and 7% with 70.2 Gy, respectively.
Although overall survival did not increase, “we did see significantly lower rates of recurrence, tumor growth, and metastatic disease in the [higher radiation] group,” said Dr. Michalski in a Washington University news release. Overall, “the patients in the trial did better than we anticipated…[possibly] because of improvements in metastatic cancer therapy over the 10 years of the trial.”
The subjects’ median age was 71 years; all were participating in the NRG Oncology/RTOG 0126 trial and were randomized between March 2002 and August 2008. At randomization, 70% had prostate-specific antigen levels < 10 ng/mL, 84% had a Gleason score of 7, and 57% had T1 disease.