LAUSR

2068Background: Leptomeningeal disease (LMD) is a common but morbid disease progression after craniotomy for resection of brain metastases (BrM). LMD has been observed most commonly with breast cancer BrM, but the cellular mechanisms facilitating LMD have not been elucidated. We sought to identify a protein associated with a higher risk of developing LMD. Methods: At our institution, patients (2005-2016) who had craniotomy for BrM followed by adjuvant radiation therapy were eligible for this IRB approved study. Frozen BrM samples were reduced with trypsin digestion, pelleted by centrifugation, and analyzed by liquid chromatography–mass spectrometry. Mass spectra were searched with Sequest HT algorithm in Proteome Discoverer v2.1 (Thermo Scientific). Patient outcomes were obtained from the medical record and overall survival (OS) and time-to-event were calculated with Kaplan-Meier and Competing Risk. To identify proteins of interest, we used empirical Bayes based linear models (limma) and the Benjamini–Hoc...