Stereotactic radiosurgery for large brain metastases

Abstract

We evaluated patient outcomes following stereotactic radiosurgery (SRS)-treatment of large brain metastasis (⩾3cm) at our institution. SRS is an established treatment for limited brain metastases. However, large tumors pose a challenge for this approach. For this study, 343 patients with 754 total brain metastases were treated with SRS, of which 93 had large tumors. The tumor size was 3–3.5, 3.5–4, and ⩾4cm in 29%, 32%, and 39% of these patients. Surgical resection was performed prior to SRS in 68% of patients, and 53% achieved a gross total resection. The local control of large metastases was inferior compared to smaller tumors, with 1year local control of 68 versus 86%, respectively (p<0.001). Among the patients with large metastases, no correlation between local control and surgical resection (p=0.747), or extent of surgery (gross total versus subtotal resection; p=0.120), was identified. Histology (p=0.939), tumor size (3–4 versus >4cm; p=0.551), and SRS dose (⩽16 versus >16Gy; p=0.539) also showed no correlation with local failure. The overall survival at 1, 2, and 5years was 46%, 29% and 5%, respectively. Prolonged survival was seen in patients with age <65years (p=0.009), primary treatment compared with salvage (p=0.077), and controlled primary tumors (p=0.022). Radiation necrosis developed in 10 patients (11.8%). For patients with large brain metastases, SRS is well tolerated and can achieve local central nervous system disease control in the majority of patients, and extended survival in some, though the local control rate is suboptimal. Further strategies to improve the outcomes in this subgroup of patients are needed.