Risk factors associated with leptomeningeal metastases after postoperative stereotactic radiotherapy for brain metastases

Abstract Introduction: Neurosurgical resection is the standard treatment for large brain metastases (BMs). Perioperative tumor spill is an important complication which is theorized to contribute to leptomeningeal disease (LMD). Postoperative stereotactic radiotherapy (SRT) is used to improve local control, but does not always prevent LMD. This study aims to identify patients at increased risk of developing LMD after postoperative SRT. Methods: We included 147 patients who underwent resection and SRT for BMs. Univariable and multivariable Cox regression analyses were used to assess associations of LMD with various patient characteristics. Results: Median survival after postoperative SRT was 14 months (IQR 6-30) with 3-year actuarial survival rate of 21%. LMD was diagnosed in 21/147 patients (14%; 3-year actuarial rate 26%). Patients with resected cerebellar metastases were more likely to develop LMD than those with cerebral metastases (HR 4.24, 95% CI 1.11-16.3, P = 0.035). Incidence of LMD for cerebellar metastases was 9/40 (23%; 3-year actuarial rate 46%) and 12/107 (11%; 3-year actuarial rate 17%) in cerebral metastases. Median survival after LMD diagnosis was 4 months. Conclusion: Patients with a resected cerebellar BM were at increased risk to develop LMD compared to patients with cerebral BMs. Survival after LMD was poor, highlighting the need for effective preventative strategies.