Fractionated radiosurgery, which delivers focused radiation therapy over three to five sessions after brain metastases surgery, reduces cancer recurrence and improves overall survival compared to single-session radiation treatment, while maintaining a similar safety profile.
- Fractionated radiosurgery (fSRS) improved one-year surgical bed control to 87% compared to 81% with conventional stereotactic radiosurgery (SRS)
- Median overall survival increased to 29 months with fSRS versus 20 months with SRS, a statistically significant improvement (p = 0.03)
- Fractionated treatment failure rate was only 4% compared to 11% with single-session radiation
- Both treatment approaches showed similar safety profiles, with no significant differences in adverse events like radiation necrosis or cerebral edema
- Study included 242 randomized patients treated between 2019-2022, providing robust clinical evidence for this approach
Fractionated radiosurgery can reduce cancer recurrence after surgery for large brain metastases, suggest findings presented September 28 at the American Society for Radiation Oncology (ASTRO) annual meeting in Boston.
In his presentation, Paul Brown, MD, from the Mayo Clinic in Rochester, MN discussed findings showing that delivering focused radiation therapy over three to five sessions after surgery for a large brain metastasis reduced recurrence risk compared with delivering radiation in one session.
“Dividing the radiation dose over several treatments gives healthy tissue time to recover between doses while still delivering an effective dose to the treatment area,” said Brown in a prepared statement. “By fractionating the treatment, we were able to improve local control while maintaining a similar safety profile.”
While brain metastases are often treated via surgery, radiation therapy afterward is important to address the possibility of cancer recurrence. For patients with a small to moderate number of removed brain tumors, focused radiation targeted at the surgical site is preferred over whole-brain radiation, because it better protects memory and quality of life.
However, the best way to deliver that focused radiation for larger surgical cavities has not yet been established.
Brown shared results from the Alliance A071801 trial, with he and colleagues studying whether time to surgical bed failure is increased with fractionated stereotactic radiosurgery (fSRS) compared to conventional stereotactic radiosurgery (SRS) in patients with resected brain metastasis.
The study included 242 randomized patients who were treated between 2019 and 2022. Brown reported median surgical cavity target volumes of 16.5 cm3 for fSRS and 14.8 cm3 for SRS (p = 0.41).
The researchers also found higher surgical bed control, less failure of treated, unresected brain metastases, and higher overall survival in the fSRS arm.
Comparison between fSRS, SRS | |||
Measure | SRS | fSRS | P value |
Surgical bed control (one-year rate) | 81% | 87% | 0.05 |
Failure rate | 11% | 4% | 0.06 |
Overall survival | 20 months | 29 months | 0.03 |
A stratified multivariable model that included the other baseline variables also found links between the fSRS arm and overall survival, with a hazard ratio of 0.68 (p = 0.03).
Finally, Brown said the team observed no significant differences in adverse event rates between both study arms. Grade 1+ radiation necrosis and cerebral edema were 14% and 8% in the fSRS arm and 10% and 9% in the SRS arm, respectively.
“We were pleased to see better control at the surgical site because that finding aligns closely with the retrospective evidence that led us to undertake this trial,” Brown said. “But the survival difference was surprising, and we cannot say with certainty why it occurred. As modern treatments help patients live longer with cancer, maintaining control of disease in the brain may play an increasingly important role in long-term outcomes.”
Read AuntMinnie’s full coverage of ASTRO 2026 here.
