Purpose: To evaluate the efficacy of gamma knife radiosurgery (GKS) for brain metastases (BMs) from small-cell lung cancer after whole-brain radiotherapy (WBRT).
Methods: We retrospectively analyzed the usefulness and safety of GKS in 163 patients from 15 institutions with 1-10 active BMs after WBRT. The usefulness and safety of GKS were evaluated using statistical methods.
Results: The median age was 66 years, and 79.1% of patients were men. The median number and largest diameter of BM were 2.0 and 1.4 cm, respectively. WBRT was administered prophylactically in 46.6% of patients. The median overall survival (OS) was 9.3 months, and the neurologic mortality was 20.0%. Crude incidences of local control failure and new lesion appearance were 36.6% and 64.9%, respectively. A BM diameter ≥ 1.0 cm was a significant risk factor for local progression (hazard ratio [HR] 2.556, P = 0.039) and neurologic death (HR 4.940, P = 0.031). Leukoencephalopathy at the final follow-up was more prevalent in the therapeutic WBRT group than in the prophylactic group (P = 0.019). The symptom improvement rate was 61.3%, and neurological function was preserved for a median of 7.6 months. Therapeutic WBRT was not a significant risk factor for OS, neurological death, local control, or functional deterioration (P = 0.273, 0.490, 0.779, and 0.560, respectively). Symptomatic radiation-related adverse effects occurred in 7.4% of patients.
Conclusions: GKS can safely preserve neurological function and prevent neurologic death in patients with 1-10 small, active BMs after prophylactic and therapeutic WBRT.
Keywords: Brain metastases; Gamma knife radiosurgery; Leukoencephalopathy; Small-cell lung cancer; Whole-brain radiation therapy.