Safety and efficacy of upfront stereotactic radiosurgery for brain metastases with high cumulative intracranial tumor volume (> 7 ml): analysis of 233 consecutive patients

Abstract

The cumulative intracranial tumor volume (CITV) has recently been suggested to be a more relevant predictive factor for patients with brain metastases (BM) treated with stereotactic radiosurgery (SRS). We aimed to investigate the feasibility of upfront SRS for patients with BM having a high CITV, i.e., exceeding 7ml. Two hundred thirty-three consecutive patients with BM having a CITV > 7ml who underwent SRS as first-line treatment from 2011 to 2019 were retrospectively identified. The overall survival (OS) and intracranial disease control rates were analyzed. Multivariate proportional hazards models were used to identify prognostic factors associated with treatment outcome. Toxicity and salvage therapy were also investigated. The median OS was 8.7months (95% confidence interval: 7.1-10.4), and 6-month and 1-year OS rates were 60 and 40%, respectively. Systemic anticancer therapy (hazard ratio (HR): 0.45, p < 0.001), female sex (HR: 0.61, p = 0.001), synchronous SRS (HR: 0.57, p = 0.003), number of BM (HR: 1.04, p = 0.008), controlled extracranial disease (HR: 0.56, p = 0.009), Karnofsky performance status (HR: 0.87, p = 0.015), and staged SRS (HR: 0.71, p = 0.037) were found to be factors independently associated with OS. Post-SRS toxicities of CTCAE grades 3, 4, and 5 were observed in 14, 5, and 1 patient, respectively. As salvage management, repeat SRS, whole brain radiotherapy, and surgical resection were required for 84, 16, and 10 patients, respectively, CONCLUSIONS: With vigilant surveillance and appropriate salvage management, upfront SRS alone can be considered as a relatively safe and effective treatment strategy even for BM with CITV > 7ml.