SURG-25. EFFECT OF VENTRICULAR ENTRY DURING GLIOBLASTOMA RESECTION ON PATIENT OUTCOMES

Abstract BACKGROUND Tumor proximity to the ventricle and ventricular entry (VE) during surgery have both been associated with poorer prognoses; however, the interaction between these two factors is poorly understood. METHODS The UCSF tumor registry was searched for patients with newly diagnosed and recurrent supratentorial glioblastoma who underwent surgical resection with the senior author between 2013 – 2018. Tumor location with respect to the subventricular zone (SVZ), size, VE, and extent of resection were assessed using pre and postoperative imaging. RESULTS In the 200-patient cohort of newly diagnosed and recurrent glioblastoma, 26.5% had VE. Comparing patients with VE to those without VE, there was no difference in postoperative hydrocephalus (1.9% vs. 4.8%, p = 0.36), ventriculoperitoneal shunting (0% vs. 3.4%, p = 0.17), pseudomeningoceles (7.5% vs. 5.4%, p = 0.58), or subdural hematomas (11.3% vs. 3.4%, p = 0.07). Importantly, rates of leptomeningeal disease (7.5% in VE vs. 10.2% w/o VE, p = 0.57) and distant parenchymal recurrence (17.9% in VE vs. 23.1% w/o VE, p = 0.35) were not different between the groups. There was no effect of VE on EOR when controlling for SVZ type. Newly diagnosed patients with tumors contacting the SVZ (Type 1 or 2) had worse survival than patients with tumors that did not contact the SVZ (Type 3 or 4) (1.27 vs 1.84 years, p = 0.014, HR 1.8, CI 1.08 – 3.03), but VE was not associated with worse survival in these patients with high risk SVZ Type 1 and 2 tumors (1.15 vs 1.68 years, p = 0.151, HR 0.59, CI 0.26 – 1.34). DISCUSSION VE was well tolerated with complications being rare events. There was no increase in leptomeningeal spread or distant parenchymal recurrence in patients with VE. Finally, VE did not change survival for patients with tumors contacting the ventricle.