Long-Term Outcomes With Standard vs Dose-Escalated Radiation Therapy in Intermediate-Risk Prostate Cancer
As reported in JAMA Oncology by Michalski et al, long-term follow-up in the NRG Oncology/RTOG 0126 trial showed no significant difference in overall survival with dose-escalated vs standard-dose radiotherapy in patients with intermediate-risk prostate cancer. High-dose radiotherapy was associated with more late toxic effects but less use of salvage therapy.
Study Details
In the trial, 1,499 evaluable patients from 104 North American Radiation Therapy Oncology Group institutions were randomized between March 2002 and August 2008 to receive 3-dimensional conformal radiation therapy or intensity-modulated radiation therapy to 79.2 Gy in 44 fractions (n = 751) or 70.2 Gy in 39 fractions (n = 748). Patients had to have stage cT1b to T2b disease, Gleason score of 2 to 6 and prostate-specific antigen (PSA) level of ≥ 10 and < 20 ng/mL, or Gleason score of 7 and PSA < 15 ng/mL. American Society for Therapeutic Radiology and Oncology (ASTRO)/Phoenix definitions were used for biochemical failure.
Overall Survival and Late Toxicity
Median follow-up was 8.4 years. Overall survival at 8 years was 76% in the 79.2 Gy group vs 75% in the 70.2 Gy group (hazard ratio [HR] = 1.00, P = .98). The 8-year cumulative rate of distant metastases was 4% vs 6% (HR = 0.65, P = .05).
The ASTRO and Phoenix biochemical failure rates at 5 and 8 years were 31% and 20% in the 79.2 Gy group and 47% and 35% in the 70.2 Gy group (HR for ASTRO definition = 0.59, HR for Phoenix definition = 0.54, both P < .001). Salvage therapy was used in 14.8% of the 79.2 Gy group vs 22.5% of the 70.2 Gy group (P < .001), with a cumulative incidence of salvage therapy of 9% vs 15% at 5 years and 14% vs 22% at 8 years.
The 5-year rates of late grade ≥ 2 gastrointestinal and genitourinary toxic effects were 21% (HR = 1.39, P = .006) and 12% (HR = 1.59, P = .003) with 79.2 Gy vs 15% and 7% with 70.2 Gy.
The investigators concluded, “Despite improvements in biochemical failure and distant metastases, dose escalation did not improve [overall survival]. High doses caused more late toxic effects but lower rates of salvage therapy.”
The study was supported by grants from the National Cancer Institute.
Jeff M. Michalski, MD, MBA, of the Department of Radiation Oncology, Washington University School of Medicine, is the corresponding author for the JAMA Oncology article.
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