Stereotactic ablative radiotherapy for the comprehensive treatment of 1-3 Oligometastatic tumors (SABR-COMET-3): Study protocol for a randomized phase III trial

Robert Olson, Lindsay Mathews, Mitchell Liu, Devin Schellenberg, Benjamin Mou, Tanya Berrang, Stephen Harrow, Rohann J.M. Correa, Vasudeva Bhat, Howard Pai, Islam Mohamed, Stacy Miller, Famke Schneiders, Joanna Laba, Derek Wilke, Sashendra Senthi, Alexander V. Louie, Anand Swaminath, Anthony Chalmers, Stewart GaedeAndrew Warner, Tanja D. De Gruijl, Alison Allan, David A. Palma

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Background: A recent randomized phase II trial evaluated stereotactic ablative radiotherapy (SABR) in a group of patients with a small burden of oligometastatic disease (mostly with 1-3 metastatic lesions), and found that SABR was associated with a significant improvement in progression-free survival and a trend to an overall survival benefit, supporting progression to phase III randomized trials. Methods: Two hundred and ninety-seven patients will be randomized in a 1:2 ratio between the control arm (consisting of standard of care [SOC] palliative-intent treatments), and the SABR arm (consisting of SOC treatment + SABR to all sites of known disease). Randomization will be stratified by two factors: histology (prostate, breast, or renal vs. all others), and disease-free interval (defined as time from diagnosis of primary tumor until first detection of the metastases being treated on this trial; divided as ≤2 vs. > 2 years). The primary endpoint is overall survival, and secondary endpoints include progression-free survival, cost effectiveness, time to development of new metastatic lesions, quality of life (QoL), and toxicity. Translational endpoints include assessment of circulating tumor cells, cell-free DNA, and tumor tissue as prognostic and predictive markers, including assessment of immunological predictors of response and long-term survival. Discussion: This study will provide an assessment of the impact of SABR on survival, QoL, and cost effectiveness to determine if long-term survival can be achieved for selected patients with 1-3 oligometastatic lesions. Trial registration: identifier: NCT03862911. Date of registration: March 5, 2019,

Original languageEnglish
Article number380
Number of pages12
JournalBMC Cancer
Issue number1
Publication statusPublished - 5 May 2020
Externally publishedYes


  • Cancer
  • Oligometastases
  • Quality of life
  • Stereotactic radiotherapy
  • Survival

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