Stereotactic ablative radiotherapy for the comprehensive treatment of oligometastatic cancers: Long-term results of the SABR-COMET Phase II randomized trial

David A. Palma, Robert Olson, Stephen Harrow, Stewart Gaede, Alexander V. Louie, Cornelis Haasbeek, Liam Mulroy, Michael Lock, George B. Rodrigues, Brian P. Yaremko, Devin Schellenberg, Belal Ahmad, Sashendra Senthi, Anand Swaminath, Neil Kopek, Mitchell Liu, Karen Moore, Suzanne Currie, Roel Schlijper, Glenn S. BaumanJoanna Laba, X. Melody Qu, Andrew Warner, Suresh Senan

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PURPOSE The oligometastatic paradigm hypothesizes that patients with a limited number of metastases may achieve long-term disease control, or even cure, if all sites of disease can be ablated. However, long-term randomized data that test this paradigm are lacking. METHODS We enrolled patients with a controlled primary malignancy and 1-5 metastatic lesions, with all metastases amenable to stereotactic ablative radiotherapy (SABR). We stratified by the number of metastases (1-3 v 4-5) and randomized in a 1:2 ratio between palliative standard-of-care (SOC) treatments (arm 1) and SOC plus SABR (arm 2). We used a randomized phase II screening design with a primary end point of overall survival (OS), using an a of .20 (wherein P, .20 indicates a positive trial). Secondary end points included progression-free survival (PFS), toxicity, and quality of life (QOL). Herein, we present long-term outcomes from the trial. RESULTS Between 2012 and 2016, 99 patients were randomly assigned at 10 centers internationally. The most common primary tumor types were breast (n 5 18), lung (n 5 18), colorectal (n 5 18), and prostate (n 5 16). Median follow-up was 51 months. The 5-year OS rate was 17.7% in arm 1 (95% CI, 6% to 34%) versus 42.3% in arm 2 (95% CI, 28% to 56%; stratified log-rank P 5 .006). The 5-year PFS rate was not reached in arm 1 (3.2%; 95% CI, 0% to 14% at 4 years with last patient censored) and 17.3% in arm 2 (95% CI, 8% to 30%; P 5 .001). There were no new grade 2-5 adverse events and no differences in QOL between arms. CONCLUSION With extended follow-up, the impact of SABR on OS was larger in magnitude than in the initial analysis and durable over time. There were no new safety signals, and SABR had no detrimental impact on QOL.

Original languageEnglish
Pages (from-to)2830-2838
Number of pages9
JournalJournal of clinical oncology
Issue number25
Publication statusPublished - 1 Jan 2020

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