Introduction: Small cell lung cancer has a high likelihood for brain metastasis. Prophylactic cranial irradiation (PCI) and whole brain radiotherapy (WBRT) are current recommended treatment modalities. Gamma knife radiosurgery (GKR) for small cell lung cancer brain metastases (SCLCBM) has been evaluated as a salvage therapy but not as an initial treatment modality.
Methods: We performed a retrospective review of all patients undergoing GKR for SCLCBM. Only patients undergoing GKR as an initial therapy were included. Patients undergoing WBRT/PCI initially were excluded. A median dose of 18-Gy (Range 17-20) at the 50% isodose line was prescribed to the margin of each metastasis. All patients received chemotherapy (cisplatin or carboplatin/etoposide) either pre- or post-GKR. We reviewed clinical and radiographic courses of each patient; follow-up data included local control, regional control, and death from brain versus systemic disease.
Results: A total of 43 patients underwent GKR for SCLCBM. Five patients with eleven total brain metastases underwent GKR initially for SCLCBM (Male:Female, 4:1). Six lesions had radiographic follow-up. There was no local radiographic progression of treated lesions. Two lesions completely resolved; four lesions significantly decreased in size at follow-up. Median survival for patients with SCLCBM post-GKR was 6-months. Two patients also had WBRT about 5-6 months after initial GKR. From the time of diagnosis of brain metastasis, average survival of patients with SCLCBM treated with GKR as initial treatment was 15.3-months; patients treated with WBRT or PCI prior to GKR was 13.4-months (p=0.78), suggesting no statistically significant difference.
Conclusions: Initial GKR for SCLCBM can provide effective local tumor control without side effects of WBRT/PCI. GKR can significantly reduce the incidence of morbidity from brain disease by accomplishing local tumor control in patients with SCLCBM. Initial treatment of SCLCBM with GKR prior to WBRT may be an option for select patients with small cell lung cancer, warranting further investigation.
Patient Care: Use of gamma knife radiosurgery as an initial treatment of isolated small cell lung cancer brain metastases may be an option for effective local tumor control, precluding the side effects from early WBRT in this patient population.
Learning Objectives: 1. Understand the putative roles of gamma knife radiosurgery in the treatment of isolated small cell lung cancer brain metastases.
2. Describe the circumstance in which stereotactic radiosurgery is likely to be beneficial for patients with small cell lung cancer brain metastases.