Outcomes of Gamma Knife Radiosurgery in Combination with Crizotinib for Patients with Brain Metastasis from Non-Small Cell Lung Cancer.

OBJECTIVE: Crizotinib is a novel targeted anticancer agent for non-small cell lung cancer. In this study, we report our clinical outcomes from Gamma Knife radiosurgery (GKS) for brain metastasis (BM) under crizotinib treatment in non-small cell lung cancer patients.

METHODS: We performed a retrospective review of 29 patients who underwent a total of 51 GKS procedures for BM while continuing on crizotinib. We compared 2 groups on the basis of the number of BMs: oligometastases (≤5) and polymetastases (>5).

RESULTS: The actuarial 1- and 2-year overall survival rates from initial GKS were 73.5% and 42.6%, respectively. The estimated local progression-free survival (PFS) rates of the oligometastases group were 91.8% at 6 months and 84.2% at 12 months, whereas the local PFS rates of the polymetastases group at 6 and 12 months were 91.6% and 58.2%, respectively (P = 0.153). The estimated distant PFS rates of the oligometastases group were 50.7% at 6 months and 20.3% at 12 months, whereas the distant PFS rates of the polymetastases group were 32.7% at 6 months and only 6.5% at 12 months (P = 0.029).

CONCLUSIONS: GKS combined with crizotinib showed effective local tumor control and excellent outcome, especially in oligometastases. However, distant progression of BM during crizotinib after GKS occurred in most of the cases within a year. Thus brain surveillance after GKS is important for adequate and timely salvage treatment even when extracranial disease is well controlled by crizotinib.