Stereotactic ablative radiotherapy for the comprehensive treatment of 4–10 oligometastatic tumors (SABR-COMET-10): study protocol for a randomized phase III trial Journal Articles uri icon

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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.


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

publication date

  • December 2019

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