The Study: RTOG 90-05 suggested 15 Gy is the maximum safe radiosurgery dose for brain tumors >3 cm. Some argue we can achieve better local control and maintain safety by delivering higher doses over 3-5 treatments (i.e. hypofractionation). This meta-analysis of 24 international studies takes a look at single versus multifraction radiosurgery (definitive or post-op) for nearly 1900 brain mets ≥2 cm. The most common single-fraction doses were 18 Gy (range: 15-20 Gy) definitively and 15 Gy (12-15 Gy) post-op and for multifraction was 27 Gy in 3 fractions (22-39 Gy in 2-5 fractions). The dual primary endpoints of local control and radionecrosis were consistently improved across populations receiving definitive or post-op hypofractionation for targets 2-3 cm and >3 cm. The starkest (and only statistically significant) improvement was seen with radionecrosis rates, slashed from 23 → 7% with definitive hypofractionation for tumors 2-3 cm.
Bottom Line: For brain mets >2 cm, hypofractionated radiosurgery achieved numerically better local control and minimized rates of radionecrosis across tumor size and setting compared to single-fraction treatment. | Lehrer, Int J Radiat Oncol Biol Phys 2018