Where Do Surgical Resection and Radiosurgery Fall Short for Large Metastatic Brain Lesions?

Abstract

INTRODUCTION: Stereotactic radiosurgery is established as the optimal treatment modality for metastatic disease of the brain, but there is ongoing debate about the optimal treatment for larger brain metastases. There have been few studies identifying and quantifying lesion characteristics where efficacy and local control of these lesions suffer. METHODS: We retrospectively identified patients who received surgical resection and/or hypofractionated Gamma Knife radiosurgery (HF-GKRS) between 2017 and 2022 for the treatment of metastatic brain tumors greater than 10cc. Clinical, treatment, and radiological data was collected. Local failure (LF) events were examined, and independent factors associated with subsequent local failure were identified. RESULTS: 105 lesions greater than 10cc (in 97 patients) were treated and the median patient follow-up was 10.1 months. The median gross tumor volume was 15.8cc (range 10.1-62.4). Prior surgical resection was performed on 49 lesions (54%). Tumor volume larger than 33.5cc (p = 0.029, 12-month LF rate 38%) and radioresistant histology (p=0.047, 12-month LF rate 54%) were associated with increased risk of LF (p=0.018) whereas surgical resection did not correlate with increased LC (p = 0.642, 12-month LF rate 19%). CONCLUSIONS: Patients with brain metastases that are greater than 4cm in diameter or are of radioresistant histology (primary origin of gastrointestinal adenocarcinoma, melanoma, or renal cell carcinoma) are especially prone to local failure despite aggressive surgical resection, stereotactic radiosurgery, and systemic chemotherapy. In these cases, the optimal management needs to be further elucidated and may involve preoperative stereotactic radiosurgery or intraoperative brachytherapy.