TUESDAY, Oct. 6, 2026 (HealthDay News) -- After resection of larger brain metastases, fractionated stereotactic radiosurgery (fSRS) offers superior surgical bed control than single-fraction stereotactic radiosurgery (SRS), according to a study presented at the annual meeting of the American Society for Radiation Oncology (ASTRO), held from Sept. 26 to 30 in Boston.
Paul D. Brown, M.D., from the Mayo Clinic in Rochester, Minnesota, and colleagues compared the efficacy of fSRS versus SRS in patients with one to four brain metastases after resection of one lesion ≥2 cm. The analysis included 242 patients randomly assigned to either SRS (12 to 20 Gy by volume) or fSRS (27 Gy/3 <30 cc or 30 Gy/5 ≥30 cc) for intact metastases.
The researchers found that during a median follow-up of 48 months, surgical bed control was significantly higher in the fSRS group versus the SRS group (one-year rate, 87 versus 81 percent). With SRS, failure of treated, unresected brain metastases occurred in 11 percent of participants compared with 4 percent with fSRS. fSRS was also favored for overall survival (median, 29 months versus 20 months with SRS; stratified Cox hazard ratio, 0.69). When accounting for other baseline variables, there was a similar association with overall survival (hazard ratio, 0.68). Adverse event rates were similar between the groups, with grade 1+ radiation necrosis and cerebral edema seen in 14 and 8 percent of the fSRS group, respectively, versus 10 and 9 percent of the SRS group, respectively.
"This study moves fractionated radiosurgery from a reasonable practice supported by retrospective data to one backed by a randomized phase 3 trial," coauthor Ayal A. Aizer, M.D., from Mass General Brigham/Dana-Farber Cancer Institute in Boston, said in a statement. "We now have the strongest evidence to date that three to five sessions should be considered a standard postoperative treatment for patients with larger brain metastases."
