The Efficacy of Maximal Tumor Resection Combined With Whole Ventricle Radiotherapy in Patients With Glioblastoma Involving the Ventricle.

Purpose/objective(s) Patients with glioblastoma (GBM) that involve the ventricle are at higher risk of ventricle opening during surgery and potential ventricular tumor spread. We evaluated the role of whole ventricular radiotherapy (WVRT) during postoperative temozolomide-based chemoradiotherapy. Materials/methods A retrospective review of 382 patients with GBM who received surgical resection followed by temozolomide-based chemoradiotherapy between 2005 to 2019 at a single institution was conducted. Propensity score matching was performed to compensate the difference in characteristics between patients that did (WVRT(+); n = 59) or did not (WVRT(-); n = 323) receive WVRT. Local, outfield, intraventricular, and leptomeningeal failure rates were compared. Results All WVRT(+) patients had tumor ventricle involvement and ventricle opening during surgery. In the propensity matched cohort, WVRT(+) group exhibited a significantly lower 2-year intraventricular failure rate compared to the WVRT(-) group (2.1% vs. 11.8%; P = 0.045), but no difference in other treatment outcomes. Recursive partitioning analysis stratified patients at higher risk of intraventricular failure (tumor ventricle involvement, MGMT unmethylation, and ventricle opening) with a 2-year rate of 14.2%. WVRT reduced intraventricular failure rates only in high-risk patients (0% vs. 14.2%; P = 0.054) or those with MGMT-unmethylated GBM in the matched cohort (0% vs. 17.3%; P = 0.036). WVRT did not cause a significant decline in performance status but caused a decrease in post-treatment absolute lymphocyte count, although it was recovered to a similar level with that of the WVRT(-) group. Conclusion WVRT reduced intraventricular failure rates in patients with tumor ventricle involvement and ventricle opening during surgery. Our results merit further prospective evaluation of WVRT in GBM. Author disclosure K. Kim: None. J. Yoo: None. S. Kang: None. J. Chang: None. H. Yoon: None. C. Suh: None.