MET-02 Neoadjuvant fractionated stereotactic radiotherapy followed by surgery for large brain metastasis with difficulty in en-block resection

BACKGROUND: Large brain metastases which require resection are treated with surgery followed by whole brain radiation therapy or postoperative stereotactic radiosurgery (SRS). Recently a novel strategy using neoadjuvant stereotactic radiosurgery (Na-SRS) followed by surgery was reported, demonstrating lower rates of postoperative leptomeningeal dissemination (LMD) and symptomatic radiation necrosis (sRN). However, local control rate was not significantly improved. We treated with neoadjuvant fractionated stereotactic radiotherapy (Na-frSRT) followed by surgery for large brain metastasis with difficulty in en-block resection. METHODS: Nine patients received Na-frSRT followed by surgery between July 2019 and June 2020. Na-frSRT dose was based on lesion size and was standard dosing. Surgery generally followed within 7 days after radiotherapy. RESULTS: The mean age was 64 years (55–78). Eight men and one woman. Median follow-up period was 5.3 months (1.7–12.5). Primary cancers were non-small cell lung cancer 2, esophageal cancer 2, colon cancer 1, melanoma 1, hepato-cellular carcinoma 1 and recurrence of BM from small cell lung cancer and renal cell cancer. The median maximum tumor diameter was 4.3cm (2.6–4.9). The median SRT dose was 30Gy/5fr, and the median time from SRT to surgery was 4 days (1–7). Median PTV was 15.4ml (5.6–49.7), and median GTV was 21.7ml (8.6–61.4). As preoperative adverse event, intracranial hypertension grade2 (CTCAE ver.4.0) was occurred one patient, but controlled with steroid and osmotic diuretics. Grade 3 and more adverse events were not occurred. Gross total resection with intra-tumoral decompression and piece-meal technique was performed in all cases as planning. Event cumulative incidence as follows: surgical site recurrence 0%; local recurrence 11.1%; distant brain failure 11.1%; LMD 0%; and sRN 0%. The median overall survival was not reached. CONCLUSIONS: Na-frSRT followed by surgery is safety and feasible, and may have therapeutic value for large brain metastasis. Further prospective investigations in multi-institutional settings are warranted.