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Original Investigation
March 15, 2018

Effect of Standard vs Dose-Escalated Radiation Therapy for Patients With Intermediate-Risk Prostate CancerThe NRG Oncology RTOG 0126 Randomized Clinical Trial

Author Affiliations
  • 1Washington University, St Louis, Missouri
  • 2NRG Oncology Statistics and Data Management Center, Philadelphia, Pennsylvania
  • 3University of California Davis School of Medicine, Sacramento
  • 4Imaging and Radiation Oncology Core Group, St Louis, Missouri
  • 5Emory University, Atlanta, Georgia
  • 6Centre Hospitalier de l’Université de Montréal–Notre Dame, Montreal, Quebec, Canada
  • 7Tom Baker Cancer Centre, Calgary, Alberta, Canada
  • 8McGill University, Montreal, Quebec, Canada
  • 9Cross Cancer Institute, Edmonton, Alberta, Canada
  • 10Toronto-Sunnybrook Regional Cancer Centre, Toronto, Ontario, Canada
  • 11University of Michigan Medical Center, Ann Arbor
  • 12now with William Beaumont Oakland University Medical School, Dearborn, Michigan
  • 13Akron City Hospital, Akron, Ohio
  • 14London Regional Cancer Program, London, Ontario, Canada
  • 15McMaster University, Juravinski Cancer Center, Hamilton, Ontario, Canada
  • 16L’Hotel-Dieu de Quebec, Quebec City, Quebec, Canada
  • 17Cedars-Sinai Medical Center, Los Angeles, California
JAMA Oncol. Published online March 15, 2018. doi:10.1001/jamaoncol.2018.0039
Key Points

Question  Does dose-escalated radiation therapy improve outcomes for men treated for localized prostate cancer?

Findings  In this randomized clinical trial, dose escalation was associated with a significant improvement in the rates of clinical end points such as biochemical control and distant metastases, but there was no significant improvement in overall survival. Patients who received high-dose radiation therapy had less need for salvage local or systemic therapy.

Meaning  Radiation dose escalation did not improve overall survival but reduced the need for secondary therapies.

Abstract

Importance  Optimizing radiation therapy techniques for localized prostate cancer can affect patient outcomes. Dose escalation improves biochemical control, but no prior trials were powered to detect overall survival (OS) differences.

Objective  To determine whether radiation dose escalation to 79.2 Gy compared with 70.2 Gy would improve OS and other outcomes in prostate cancer.

Design, Setting, and Participants  The NRG Oncology/RTOG 0126 randomized clinical trial randomized 1532 patients from 104 North American Radiation Therapy Oncology Group institutions March 2002 through August 2008. Men with stage cT1b to T2b, Gleason score 2 to 6, and prostate-specific antigen (PSA) level of 10 or greater and less than 20 or Gleason score of 7 and PSA less than 15 received 3-dimensional conformal radiation therapy or intensity-modulated radiation therapy to 79.2 Gy in 44 fractions or 70.2 Gy in 39 fractions.

Main Outcomes and Measures  Time to OS measured from randomization to death due to any cause. American Society for Therapeutic Radiology and Oncology (ASTRO)/Phoenix definitions were used for biochemical failure. Acute (≤90 days of treatment start) and late radiation therapy toxic effects (>90 days) were graded using the National Cancer Institute Common Toxicity Criteria, version 2.0, and the RTOG/European Organisation for the Research and Treatment of Cancer Late Radiation Morbidity Scoring Scheme, respectively.

Results  With a median follow-up of 8.4 (range, 0.02-13.0) years in 1499 patients (median [range] age, 71 [33-87] years; 70% had PSA <10 ng/mL, 84% Gleason score of 7, 57% T1 disease), there was no difference in OS between the 751 men in the 79.2-Gy arm and the 748 men in the 70.2-Gy arm. The 8-year rates of OS were 76% with 79.2 Gy and 75% with 70.2 Gy (hazard ratio [HR], 1.00; 95% CI, 0.83-1.20; P = .98). The 8-year cumulative rates of distant metastases were 4% for the 79.2-Gy arm and 6% for the 70.2-Gy arm (HR, 0.65; 95% CI, 0.42-1.01; P = .05). The ASTRO and Phoenix biochemical failure rates at 5 and 8 years were 31% and 20% with 79.2 Gy and 47% and 35% with 70.2 Gy, respectively (both P < .001; ASTRO: HR, 0.59; 95% CI, 0.50-0.70; Phoenix: HR, 0.54; 95% CI, 0.44-0.65). The high-dose arm had a lower rate of salvage therapy use. 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 (P = .006 [HR, 1.39; 95% CI, 1.10-1.77] and P = .003 [HR, 1.59; 95% CI, 1.17-2.16], respectively).

Conclusions and Relevance  Despite improvements in biochemical failure and distant metastases, dose escalation did not improve OS. High doses caused more late toxic effects but lower rates of salvage therapy.

Trial Registration  clinicaltrials.gov Identifier: NCT00033631

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