SABR-COMET’s tail’s tail

Top Line: What’s better than long-term outcomes from SABR-COMET?

The Study: Longer-term outcomes. Again, this phase 2 trial included 99 patients with 1-3 (n= 92) or up to 4-5 (n= 7) mets from any cancer without progression at the primary site at least 3 months after definitive treatment. So far we’ve seen that those randomized to stereotactic ablative radiation (SABR) had improvements in overall survival at 5 years from 18 → 42% and in median survival time from 28 → 50 months. While that’s nothing to scoff at, it does bring up the unique question in this setting of long-term toxicity. As such, prior to initial analysis, planned follow-up was extended from 5 to 10 years. Here we learn that rates of grade 2+ toxicity at 8 years were 30% in the SABR arm—mostly pain after treatment of bone mets—and 9% without. There was no grade 3+ toxicity emerging after 2 years. Of practical concern, patients were significantly less likely to require cytotoxic chemo after SABR (33%) than without (55%). What’s more, clear discrepancies in rates of both progression-free (0 → 21%) and overall (14 → 27%) survival remain at 8(!) years.

TBL: More than one in five (21%) patients are alive without recurrence out past 8 years from SABR for oligomets with no emergence of new grade 3+ toxicities. | Harrow, Int J Radiat Oncol Biol Phys 2022