The Headline: Fractionated SRS is the way to go when treating brain metastasis resection cavities.
The Study: The N107C trial found that local control was worse with single fraction SRS than whole brain radiation for resected brain metastases. The concern is that relatively large resection cavity volumes result in the use of relatively low single fraction doses. In Alliance A071801, 242 patients with 1-4 brain metastases and at least one measuring 2cm or more that was resected were randomized to receive single fraction SRS or fractionated SRS. Doses were guided by cavity volumes with single fraction doses ranging from 12-20 Gy, and fractionated doses were 27 Gy in 3 fractions for targets <30 cc and 30 Gy in 5 fractions for larger targets. Median target volume size was 14.8 cc in the single fraction arm and 16.5 cc in the fractionated arm. At 1 year, surgical bed control was significantly higher with fSRS (87% v 81%). Failure of unresected mets was similar, but also favored fSRS (4% v 11%). Most interesting was significantly higher median OS in the fSRS arm (29 v 20 months).
TBL: In A071801, fractionated SRS has superior control for brain met resection cavities when compared with single fraction SRS. | Brown, ASTRO 2026
The Study: The N107C trial found that local control was worse with single fraction SRS than whole brain radiation for resected brain metastases. The concern is that relatively large resection cavity volumes result in the use of relatively low single fraction doses. In Alliance A071801, 242 patients with 1-4 brain metastases and at least one measuring 2cm or more that was resected were randomized to receive single fraction SRS or fractionated SRS. Doses were guided by cavity volumes with single fraction doses ranging from 12-20 Gy, and fractionated doses were 27 Gy in 3 fractions for targets <30 cc and 30 Gy in 5 fractions for larger targets. Median target volume size was 14.8 cc in the single fraction arm and 16.5 cc in the fractionated arm. At 1 year, surgical bed control was significantly higher with fSRS (87% v 81%). Failure of unresected mets was similar, but also favored fSRS (4% v 11%). Most interesting was significantly higher median OS in the fSRS arm (29 v 20 months).
TBL: In A071801, fractionated SRS has superior control for brain met resection cavities when compared with single fraction SRS. | Brown, ASTRO 2026