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.
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 α 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.
Between 2012 and 2016, 99 patients were randomly assigned at 10 centers internationally. The most common primary tumor types were breast (n = 18), lung (n = 18), colorectal (n = 18), and prostate (n = 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 = .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 = .001). There were no new grade 2-5 adverse events and no differences in QOL between arms.
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.
Journal of clinical oncology : official journal of the American Society of Clinical Oncology. 2020 Jun 02 [Epub]
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 Bauman, Joanna Laba, X Melody Qu, Andrew Warner, Suresh Senan
London Health Sciences Centre, London, Ontario, Canada., BC Cancer, Centre for the North, Prince George, British Columbia, Canada., Beatson West of Scotland Cancer Centre, Glasgow, Scotland., Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada., Amsterdam University Medical Center, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands., Nova Scotia Cancer Centre, Halifax, Nova Scotia, Canada., BC Cancer, Surrey Centre, Surrey, British Columbia, Canada., Alfred Health Radiation Oncology, Melbourne, Victoria, Australia., Juravinski Cancer Centre, Hamilton, Ontario, Canada., McGill University Health Centre, Montreal, Quebec, Canada., BC Cancer, Vancouver Centre, Vancouver, British Columbia, Canada.