Impact of maximal extent of resection on postoperative deficits, patient functioning, and survival within clinically important glioblastoma subgroups.

Background: The impact of extent of resection (EOR), residual tumor volume (RTV), and gross-total resection (GTR) in glioblastoma subgroups is currently unknown. This study aimed to analyze their impact on patient subgroups in relation to neurological and functional outcomes.

Methods: Patients with tumor resection for eloquent glioblastoma between 2010 and 2020 at 4 tertiary centers were recruited from a cohort of 3919 patients.

Results: One thousand and forty-seven (1047) patients were included. Higher EOR and lower RTV were significantly associated with improved overall survival (OS) and progression-free survival (PFS) across all subgroups, but RTV was a stronger prognostic factor. GTR based on RTV improved median OS in the overall cohort (19.0 months, P < .0001), and in the subgroups with IDH wildtype tumors (18.5 months, P = .00055), MGMT methylated tumors (35.0 months, P < .0001), aged <70 (20.0 months, P < .0001), NIHSS 0-1 (19.0 months, P = .0038), KPS 90-100 (19.5 months, P = .0012), and KPS ≤80 (17.0 months, P = .036). GTR was significantly associated with improved OS in the overall cohort (HR 0.58, P = .0070) and improved PFS in the NIHSS 0-1 subgroup (HR 0.47, P = .012). GTR combined with preservation of neurological function (OFO 1 grade) yielded the longest survival times (median OS 22.0 months, P < .0001), which was significantly more frequently achieved in the awake mapping group (50.0%) than in the asleep group (21.8%) (P < .0001).

Conclusions: Maximum resection was especially beneficial in the subgroups aged <70, NIHSS 0-1, and KPS 90-100 without increasing the risk of postoperative NIHSS or KPS worsening. These findings may assist surgical decision making in individual glioblastoma patients.