When patients undergo surgical resection for larger brain metastases, adjuvant fractionated stereotactic radiosurgery should now replace single-fraction stereotactic radiosurgery as the clinical standard of care, according to phase 3 trial results presented at the 2026 ASTRO Annual Meeting in Boston. The findings demonstrate better local control in the surgical bed without an apparent increase in toxicity.
The Alliance A071801 trial evaluated patients with brain metastases larger than 2 centimeters. Investigators, including Dr. Paul D. Brown and Dr. Kristin V. Ballman, designed the study to test whether breaking radiation delivery into multiple sessions over several days could improve outcomes compared to delivering the full dose in a single treatment.
Alliance A071801 Trial Results For Resected Brain Metastases
The trial data showed conclusive evidence favoring fractionated stereotactic radiosurgery for surgical cavities exceeding 2 centimeters. Patients receiving fractionated treatment experienced superior local control in the surgical bed. Crude rates of radiation necrosis appeared comparable between the two arms at approximately 10% to 15%, though investigators are still awaiting finalized time-to-event analyses.
Despite the broader adoption of fractionation, single-fraction treatment retains a specific role in clinical practice. For smaller metastases or patients with a guarded lifespan due to extensive extracranial disease who prefer a single treatment day, single-fraction stereotactic radiosurgery remains a reasonable option based on individual patient and caregiver preferences.
Radiation Oncologists Extend Treatment Timelines to Prevent Recurrences
Radiation oncologists are adjusting how they counsel patients and coordinate care with neurosurgery departments. Rather than scheduling the historically typical single treatment day, clinical teams now outline a course spanning three to five days depending on the surgical cavity parameters and disease characteristics.
This extended timeline aims to prevent local recurrences, which remain complex to manage and can introduce significant symptoms. Managing a post-stereotactic radiosurgery recurrence often requires nuanced interventions, including repeat neurosurgical resection that carries associated complication risks. Distinguishing between actual tumor recurrence and radiation necrosis presents a diagnostic challenge that frequently triggers patient stress and additional testing.
Upcoming NRG Trials For Intact Brain Metastases
While the Alliance A071801 trial focused on resected cavities, investigators also analyzed data from patients with up to three unresected brain metastases. Results revealed an encouraging trend toward better local control with fractionated stereotactic radiosurgery in intact metastases, yielding a P value of .06.
To definitively address whether fractionation benefits intact tumors, the phase 3 NRG-BN013 trial (NCT06500455) has completed accrual with results pending. In addition, researchers are evaluating the paradigm of preoperative stereotactic radiation versus postoperative stereotactic radiosurgery to determine if upfront delivery minimizes meningeal seeding and reduces necrosis rates.
Frequently Asked Questions About Fractionated Stereotactic Radiosurgery
What size brain metastasis requires fractionated stereotactic radiosurgery?
The Alliance A071801 trial evaluated metastases larger than 2 centimeters, establishing fractionation as the standard for these larger surgical cavities.
What were the radiation necrosis rates in the trial arms?
Preliminary crude rates showed that approximately 10% to 15% of patients in both the single-fraction and fractionated arms experienced radiation necrosis, with no meaningful differences identified ahead of finalized time-to-event analyses.
When will results for intact brain metastases be available?
The phase 3 NRG-BN013 trial has completed patient accrual, and definitive results regarding fractionation in unresected brain metastases are currently pending.
Worth a look