Top Line: What is the optimal dose for preoperative SRS?
The Study: Preoperative SRS is used at some centers to potentially decrease the risk of radiation toxicity and the risk of leptomeningeal seeding during surgery. Many centers reduce the prescription dose for preop SRS by 10-20% from the typical doses used for intact mets. In this phase 1 dose escalation trial, 35 patients with 36 metastases measuring 2cm or greater received single fraction SRS prior to resection. The prescription dose was increased in increments of 3 Gy starting at a dose of 18 Gy for 2-3 cm mets, 15 Gy for 3-4 cm mets, and 12 Gy for 4-6 cm mets. The 2-3 cm group had no dose limiting toxicity up to a dose of 21 Gy in 1 fraction. Two acute grade 3+ events occurred in the 3-4 cm group at a dose of 21 Gy leading to a maximum tolerated dose of 18 Gy in 1 fraction for mets larger than 3 cm. One patient developed late radiation necrosis, and no patients developed leptomeningeal disease.
TBL: In this dose-escalation study, doses comparable to those used for intact mets appeared tolerable for larger resectable brain mets. Further trials will explore if dose escalation is beneficial in the preoperative setting. | Murphy, Neuro Oncol 2024
The Study: Preoperative SRS is used at some centers to potentially decrease the risk of radiation toxicity and the risk of leptomeningeal seeding during surgery. Many centers reduce the prescription dose for preop SRS by 10-20% from the typical doses used for intact mets. In this phase 1 dose escalation trial, 35 patients with 36 metastases measuring 2cm or greater received single fraction SRS prior to resection. The prescription dose was increased in increments of 3 Gy starting at a dose of 18 Gy for 2-3 cm mets, 15 Gy for 3-4 cm mets, and 12 Gy for 4-6 cm mets. The 2-3 cm group had no dose limiting toxicity up to a dose of 21 Gy in 1 fraction. Two acute grade 3+ events occurred in the 3-4 cm group at a dose of 21 Gy leading to a maximum tolerated dose of 18 Gy in 1 fraction for mets larger than 3 cm. One patient developed late radiation necrosis, and no patients developed leptomeningeal disease.
TBL: In this dose-escalation study, doses comparable to those used for intact mets appeared tolerable for larger resectable brain mets. Further trials will explore if dose escalation is beneficial in the preoperative setting. | Murphy, Neuro Oncol 2024