Stereotactic ablative radiotherapy for the comprehensive treatment of 4-10 oligometastatic tumors (SABR-COMET-10): Study protocol for a randomized phase III trial

David A. Palma, Robert Olson, Stephen Harrow, Rohann J.M. Correa, Famke Schneiders, Cornelis J.A. Haasbeek, George B. Rodrigues, Michael Lock, Brian P. Yaremko, Glenn S. Bauman, Belal Ahmad, Devin Schellenberg, Mitchell Liu, Stewart Gaede, Joanna Laba, Liam Mulroy, Sashendra Senthi, Alexander V. Louie, Anand Swaminath, Anthony ChalmersAndrew Warner, Ben J. Slotman, Tanja D. De Gruijl, Alison Allan, Suresh Senan

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Background: Stereotactic ablative radiotherapy (SABR) has emerged as a new treatment option for patients with oligometastatic disease. SABR delivers precise, high-dose, hypofractionated radiotherapy, and achieves excellent rates of local control for primary tumors or metastases. A recent randomized phase II trial evaluated 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 benefits in progression-free survival and overall survival. The goal of this phase III trial is to assess the impact of SABR in patients with 4-10 metastatic cancer lesions. Methods: One hundred and fifty-nine patients will be randomized in a 1:2 ratio between the control arm (consisting of standard of care palliative-intent treatments), and the SABR arm (consisting of standard of care treatment + SABR to all sites of known disease). Randomization will be stratified by two factors: histology (Group 1: prostate, breast, or renal; Group 2: all others), and type of pre-specified systemic therapy (Group 1: immunotherapy/targeted; Group 2: cytotoxic; Group 3: observation). SABR is to be completed within 2 weeks, allowing for rapid initiation of systemic therapy. Recommended SABR doses are 20 Gy in 1 fraction, 30 Gy in 3 fractions, or 35 Gy in 5 fractions, chosen to minimize risks of toxicity. The primary endpoint is overall survival, and secondary endpoints include progression-free survival, time to development of new metastatic lesions, quality of life, 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 clinical outcomes and quality of life, to determine if long-term survival can be achieved for selected patients with 4-10 oligometastatic lesions. Trial registration: identifier: NCT03721341. Date of registration: October 26, 2018.

Original languageEnglish
Article number816
Number of pages15
JournalBMC Cancer
Issue number1
Publication statusPublished - 19 Aug 2019
Externally publishedYes


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

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