Neuro-Oncological Superiority of Supratotal Resection in Lower-Grade Gliomas.

Background: Supratotal-Resection (SpTR) is a promising surgical strategy in Lower-grade gliomas (LGGs). SpTR assessment, feasibility and distinctive features, as well as clinical benefit at first and second surgery and on overall-survival must be better characterized. The critical percentage of resection exceeding FLAIR margins to obtain clinical benefit and its impact on long-term functional performance are also undefined.

Methods: Included were 704 patients with primary and 439 with recurrent LGGs seen between 2010-2019, who underwent resection with Brain-Mapping-Technique (BMT) aimed at achieving a SpTR without any "a-priori" selection. Extent-Of-Resection, evaluated on 3D-FLAIR-MR and categorized according to residual tumor and cavity volume, was associated with Progression-Free-Survival (PFS) and Malignant(M)PFS at first and second surgery, and Overall-Survival by univariate, multivariate and propensity-score analysis. Functional performance was assessed by neuropsychological-NPS evaluation.

Results: SpTR evaluation requires volumetric assessment enhanced by brain deformation measurement in parietal tumors; SpTR rate accounts on average for 50.2% and 35.7% at first and second surgery, is higher in grade-2, frontal and temporal locations (at expenses of Total-Resection-TR). Compared to TR, SpTR reduces and postpones first and second recurrences in all molecular subtypes and grades, delays MPFS without difference in rate and prolongs Overall-Survival. A degree of SpTR>120% associates with the lowest recurrence risk. SpTR associates with the best NPS longitudinal course.

Conclusions: This study supports feasibility of SpTR in LGGs, its benefit at first and second surgery regardless of molecular subtypes, and on Overall-Survival, significantly reducing recurrence when SpTR>120%; SpTR also associates with the best patients' functional outcome.