Pre-operative Stereotactic Radiosurgery for Patients with One to Four Brain Metastases: A Single-Arm Phase 2 Trial Outcome Analysis (NCT03398694)

Stereotactic radiosurgery (SRS) following surgical resection is the standard of care for patients with symptomatic oligo brain metastasis (BM), however, it is associated with 10-15% local failure. Targeting a resection cavity is imprecise, thus pre-operative radiosurgery where the target is well defined may be superior, however, the efficacy of pre-operative SRS has not yet been tested in a clinical trial. We conducted a phase II, single-arm trial of pre-operative SRS followed by surgical resection in patients with 1-4 symptomatic oligo BMs (NCT03398694) with the primary objective of measuring 6-month local control (LC). SRS was delivered to all patients utilizing gamma knife or linear accelerator as per RTOG-9005 dosing criteria24 based on tumor diameter with the exception that the largest lesion diameter treated was 5 cm with 15 Gy with all SRS treatment given in single fraction dosing. The trial screened 50 patients, 48 patients were treated under the protocol and 32 patients completed the entire follow-up period. Of all the patients who completed the follow-up period, primary endpoint of 6-month LC was 100% (95% CI: 0.891-1.000; p=0.005). Secondary endpoints, presented as medians, were overall-survival (17.6 months), progression-free survival (5.3 months), distant in-brain failure (40.8% at 1 year), leptomeningeal failure (4.8% at 1 year), and radiation necrosis (7.7% at 1 year). Our data confirms superior local control in patients who received pre-operative SRS when compared to historical controls. Further study with a larger randomized cohort of patients is warranted to fully understand the benefits of pre-operative SRS.