Association of Supratotal Resection with Progression-Free Survival, Malignant Transformation, and Overall Survival in Lower-Grade Gliomas

Background: supratotal resection is advocated in lower-grade-gliomas (LGGs) based on theoretical advantages, but with limited verification of functional risk and data on oncological outcomes. We assessed the association of supratotal resection in molecular-defined LGGs with oncological outcomes. Methods: 460 presumptive LGGs included; 404 resected; 347 were LGGs, 319 IDH-mutated, 28 wildtype. All patients had clinical, imaging, molecular data. Resection aimed at supratotal resection without any patient or tumor a-priori selection. The association of Extent-of-Resection (EOR), categorized on volumetric-FLAIR-images as residual-tumor-volume, along with post-surgical-management with Progression-free-survival (PFS), malignant-progression-free-survival (MPFS), and Overall-Survival (OS) assessed by univariate, multivariate, propensity-score-analysis. The study mainly focused on IDH-mutated-LGGs, the "typical LGGs". Results: Median follow-up:6.8 years(IQR:5-8). Out of 319 IDH-mutated-LGGs, 190 (59.6%) progressed, median PFS:4.7 years(95%CI:4-5.3). Total and supratotal resection obtained in 39% and 35% of patients of IDH1-mutated tumors. In IDH-mutated, most patients in partial/subtotal group progressed, 82.4% in total, only 6 (5.4%) in supratotal. Median PFS was 29 months(95%CI:25-36) in subtotal, 46 months(95%CI:38-48) in total, while at 92 months, PFS in supratotal was 94.0%. There was no association with molecular-subtypes and grade. At random-forest-analysis, PFS strongly associated with EOR,RT, previous treatment. In the propensity-score analysis, EOR associated with PFS (HR,0.03;95%CI,0.01-0.13). MPFS occurred in 32.1% of subtotal-total groups; 1 event in supratotal. EOR, grade-III, previous treatment correlated to MPFS. At random-forest analysis, OS associated with EOR as well. Conclusions: Supratotal resection strongly associated with PFS, MPFS and OS in LGGs, regardless of molecular subtypes and grade, right from the beginning of clinical presentation.