Pre-Operative Single Fraction Versus Fractionated Stereotactic Radiotherapy: A Single-Institutional Analysis of 299 Resected Metastases

Purpose The treatment standard for patients with large or symptomatic brain metastases and limited intracranial disease is surgical resection followed by post-operative stereotactic radiosurgery (SRS). Pre-operative (pre-op) SRS may lead to a reduced incidence of radiation necrosis (RN), local failure (LF), and nodular meningeal disease (nMD). Fractionated treatments may reduce the incidence of LF and nMD. We hypothesize that pre-operative fractionated stereotactic radiotherapy will reduce the incidence rate of RN, LD, and nMD compared to patients receiving pre-operative SRS. Methods Patients who had surgical resection and pre-operative radiation to at least one brain metastasis at a single institution were retrospectively analyzed. Outcomes were evaluated on a per-lesion basis. The primary outcome was a composite endpoint defined by 1) LF, 2) nMD, and/or 3) Grade 2 or higher (symptomatic) RN. Results 299 resected brain metastases from 260 patients were eligible for analysis. 235 metastases received FSRT and 64 received SRS. 38 patients had multiple metastases resected pre-operatively. Overall, 4 (6.3%) SRS and 6 (2.6%) FSRT metastases experienced LF. 4 (6.2%) SRS and 21 (9.1%) FSRT metastases experienced Grade 2 or higher RN. 3 (4.7%) SRS and 11 (4.7%) FSRT metastases were diagnosed with leptomeningeal disease. Additionally, 3 (4.6%) and 0 (0%) of SRS, and 8 (3.4%) and 4 (1.7%) of FSRT patients experienced classical or nodular meningeal disease, respectively. 11% and 12% of SRS and FSRT metastases experienced the composite endpoint. Conclusions In our study, pre-operative SRS and FSRT both appear to be safe and effective options to treat resectable brain metastases. It is important to prospectively compare pre-op SRS and FSRT in matched cohorts to assess any differences in treatment efficacy and toxicity.