Effects of ventricular entry on patient outcome during glioblastoma resection

Tumor proximity to the ventricle and ventricular entry (VE) during surgery have both been associated with worse prognoses; however, the interaction between these two factors is poorly understood. Given the benefit of maximal tumor resection, it is imperative for surgical planning and technique to know if VE has negative consequences for patient survival and tumor dissemination.

The University of California, San Francisco tumor registry was searched for patients with newly diagnosed and recurrent supratentorial glioblastoma (GBM) who underwent resection by the senior author between 2013 and 2018. Tumor location with respect to the subventricular zone (SVZ), size, and extent of resection were assessed using pre- and postoperative imaging. VE was determined by postoperative imaging and/or the operative report.

In this 200-patient cohort of newly diagnosed and recurrent GBM, 26.5% of patients had VE during resection. Patients with VE were more likely to have preexisting subependymal disease (41.5% vs 15.0%, p < 0.001). Comparing patients with VE to those without VE, there was no difference in the rates of 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 subsequent leptomeningeal disease (7.5% vs 10.2%, p = 0.57) and distant parenchymal recurrence (17.0% vs 23.1%, p = 0.35) were not different between the groups. Newly diagnosed patients with tumors contacting the SVZ (type I or II) had worse survival than patients with tumors that did not contact the SVZ (type III or IV) (1.27 vs 1.84 years, p = 0.014, HR 1.8, 95% CI 1.08-3.03), but VE was not associated with worse survival in these patients with high-risk SVZ type I and II tumors (1.15 vs 1.68 years, p = 0.151, HR 0.59, 95% CI 0.26-1.34).

VE was well tolerated, with postoperative complications being rare events. There was no increase in leptomeningeal spread or distant parenchymal recurrence in patients with VE. Finally, although survival was worse for patients with preoperative subependymal disease, VE did not change survival for patients with tumors contacting the ventricle. Therefore, VE during GBM resection is not associated with adverse patient outcomes and should be used by surgeons to enhance extent of resection.■ CLASSIFICATION OF EVIDENCE Type of question: therapeutic; study design: retrospective cohort; evidence: class II.