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Topics:
Radiation Oncology • Stereotactic Radiosurgery
What marginal SRS dose do you prescribe for brain metastases 2 cm or smaller?
A recent gamma knife retrospective study from Cleveland Clinic (Mohammadi et al., PMID 27231978) argues for the RTOG dose of 24 Gy, although the cumulative incidence of local progression at 5 years was ~4% vs ~5% in those receiving 24 Gy and <24 Gy, whereas the rates of radionecrosis were ~8.5% vs ~6.5% (symptomatic RN ~4.5% either dose), which are quite small differences. No comparison of outcomes with 19-23 Gy vs 24 Gy is provided. Are marginal doses of ~20 Gy acceptable for small lesions?
Answer from: Radiation Oncologist at Community Practice
Many gamma knife centers have gotten away from the 24 Gy marginal dose based on rates of treatment related imaging changes/radiation necrosis. At Yale, we use 22 Gy as our "top" dose. We have an ongoing prospective phase I/II trial investigating dose selection for gamma knife based on a grid of dose...
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Answer from: Radiation Oncologist at Academic Institution
We have not used 24 Gy for small lesions. Rather, 20 Gy is what we have used by default. Can we go up to 22 Gy or more, certainly yes but I would rather see data comparing that versus 20 Gy before changing doses.