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?
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Radiation Oncology · St. Francis Radiation Oncology
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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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Radiation Oncology · Columbia University Irving Medical Center
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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.
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