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 and 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 (OS). A degree of SpTR > 120% associates with the lowest recurrence risk. SpTR associates with the best NPS longitudinal course. Conclusions. This study supports the feasibility of SpTR in LGGs, its benefit at first and second surgery regardless of molecular subtypes, and on OS, significantly reducing recurrence when SpTR > 120%; SpTR also associates with the best patients' functional outcome.