Association of Supratotal Resection With Survival in Isocitrate Dehydrogenase-Mutant WHO Grade 2 and 3 Gliomas: An Individual Patient Data Meta-Analysis With Histological Subgroup Analyses of Astrocytomas and Oligodendrogliomas

BACKGROUND AND OBJECTIVES: The prognostic value of supratotal resection (STR) in isocitrate dehydrogenase (IDH)-mutant low-grade gliomas remains controversial, and its long-term survival impact has rarely been quantified at scale. Advances in functional mapping and neurosurgical techniques increasingly enable resection beyond MRI-defined tumor borders, yet comparative outcome data remain limited. METHODS: A systematic review and meta-analysis (2010-2025) was performed using reconstructed individual patient data to assess overall survival (OS) according to extent of resection. Survival data were reconstructed from published Kaplan-Meier curves using the IPDfromKM package in R. Survival was analyzed using Kaplan-Meier estimates, Cox proportional hazards models, restricted mean survival time (RMST), and time-varying hazard analyses. RESULTS: A total of 876 patients with IDH-mutant World Health Organization (WHO) grade 2 and 3 gliomas were included. Across the pooled cohort, STR was associated with significantly improved long-term OS compared with total resection (TR). In WHO grade 2 gliomas, 16-year OS was 96.3% after STR vs 66.8% after TR (P < .001), corresponding to an RMST gain of 23.7 months (P < .001). Subgroup analyses revealed substantial histological heterogeneity. In WHO grade 2 astrocytomas, STR conferred a pronounced survival benefit with an RMST gain of 32.6 months compared with TR (P < .001). In contrast, in WHO grade 2 oligodendrogliomas, STR was associated with a smaller, nonsignificant RMST difference of 7.0 months (P = .078). Time-varying Cox models consistently demonstrated higher mortality risks for TR relative to STR in the pooled cohort and in astrocytomas, whereas estimates in oligodendrogliomas were unstable due to low event numbers. CONCLUSION: STR provides a durable long-term survival benefit in IDH-mutant low-grade gliomas, particularly in WHO grade 2 tumors. The benefit is most pronounced in astrocytomas, while effects in oligodendrogliomas appear smaller and less certain. These findings support STR as the preferred surgical strategy when functionally feasible.