How do you approach the choice between 3-fx and 5-fx postop SRS for a resected brain metastasis for intermediate cavity volume?
A071801 used 27 Gy/3 for cavities <30 cc and 30 Gy/5 for >30 cc. Is there a biological rationale for that size cutoff/dosing?
This question is part of our ASTRO 2026 collaboration, inspired by the Plenary Session Presentation "Alliance A071801 Phase III Trial Postoperative Single Fraction Stereotactic Radiosurgery (SRS) vs. Fractionated SRS (fSRS) for Resected Brain Metastasis" by Dr. Paul Brown, MD
2 Answers
Mednet MemberInvited Expert
Radiation Oncology · Harvard Medical School
Answered on
Yes, decreasing the dose per fraction is a great way to increase normal tissue safety, with a small tradeoff of increasing a few more fractions. Increasing from 1 fraction to multiple fractions has enabled effective yet safe short-course radiation treatments. How few fractions we can do safely is de...
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Mednet Member
Radiation Oncology · Carolinas Medical Center
Answered on
In my practice, I generally use single-fraction SRS for lesions/cavities smaller than 2 cm in maximum dimension or ~4 cc in volume to 18 - 20 Gy, but this is a relatively rare occurrence given the fact that resected brain metastases tend to be larger.
For cavities larger than 2 cm (or about 4 cc volu...
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