Prognostic Value of Tumor Volume in Glioblastoma Patients: Size Also Matters for Patients with Incomplete Resection

Background: Incomplete resection of glioblastoma is discussed controversially in the era of combined radiochemotherapy. Objective: The aim of this study was to analyze the benefit of subtotal tumor resection for glioblastoma patients as this was recently questioned in the era of radiochemotherapy. Methods: Overall, 209 patients undergoing surgery for newly diagnosed WHO grade IV gliomas were retrospectively analyzed, and pre- and postoperative tumor volumes were manually segmented (cm³). Survival analyses were performed, including prognostic factors such as age, Karnofsky performance score (KPS), O⁶-methylguanine-DNA-methyltransferase (MGMT) promoter methylation status, and adjuvant treatment regimen. Results: Pre- and postoperative tumor volume is significantly associated with pre- and postoperative KPS, as well as age (p < 0.001). Postoperative tumor volume remained a significant prognostic factor in a multivariate analysis, independent of other prognostic factors (hazard ratio 1.0365, 95% confidence interval 1.0235–1.0497, p < 0.001). Conclusions: In the era of molecularly-driven radiochemotherapy, glioblastoma surgery remains a major prognostic factor. Even in situations in which a gross total resection cannot be achieved, maximum safe reduction of tumor burden should be attempted.