Fractionated SRS Should Be Standard of Care After Brain Metastasis Surgery

In an interview with CancerNetwork®, Ayal Aizer, MD, MHS, director of Central Nervous System Radiation Oncology at Brigham and Women’s Hospital and Dana-Farber Cancer Institute and associate professor of radiation oncology at Harvard Medical School, discussed what findings from the phase 3 Alliance A071801 trial (NCT04114981) mean for standard practice after resection of brain metastases.

Results presented at the 2026 American Society for Radiation Oncology (ASTRO) Annual Meeting showed that postoperative fractionated stereotactic radiosurgery (SRS), given as 27 Gy in 3 fractions or 30 Gy in 5 fractions depending on cavity volume, improved surgical bed control compared with single-fraction SRS at 12 to 20 Gy. Aizer said that for a typical patient with a larger resected brain metastasis, adjuvant fractionated SRS should now be the standard of care. He noted that the improvement in local control came without an apparent increase in toxicity. Crude rates of radiation necrosis were about 10% to 15% in both arms, and time-to-event analyses are expected to be finalized in the coming weeks.

Transcript:

CancerNetwork: Does this mean single-fraction SRS should no longer be the default after resection?

Aizer: That’s correct. When a typical patient with a larger brain metastasis has a resection, the standard of care should be adjuvant fractionated stereotactic radiosurgery; some people call that stereotactic radiotherapy. The study results were conclusive: better local control in the surgical bed without an apparent increase in toxicity.For your typical patient who meets those criteria, fractionation seems important.

CancerNetwork: What did toxicity and radiation necrosis rates look like between the 2 arms?

Aizer: They appear to be comparable. So far, crude rates of radiation necrosis have been analyzed. We’re still awaiting time-to-event analyses, but on average, about 10% to 15% of patients in both arms experienced radiation necrosis. There didn’t appear to be any meaningful differences, but that analysis is in preliminary form at the moment and will be finalized in the coming weeks.

References

Brown PD, Ballman KV, Aizer AA, et al. Alliance A071801 phase III trial postoperative single fraction stereotactic radiosurgery (SRS) vs fractionated SRS (fSRS) for resected brain metastasis. Presented at: 2026 ASTRO Annual Meeting; September 26–30, 2026; Boston, MA. Abstract LBA 01.