Association of Early Postoperative MRI-Based RANO-Resect With Survival in WHO 2021-Defined IDH-Mutant High-Grade Gliomas

Background Direct evidence for postoperative residual-burden stratification remains limited in WHO 2021-defined isocitrate dehydrogenase (IDH)-mutant high-grade gliomas. We evaluated whether early postoperative MRI-based Response Assessment in Neuro-Oncology resect (RANO-resect) was associated with overall survival (OS) and progression-free survival (PFS). Methods This single-center retrospective cohort study screened consecutive patients undergoing first resection for newly diagnosed diffuse glioma between May 1, 2018 and May 1, 2024. Eligibility required preoperative MRI, early postoperative MRI within 72 hours, segmentable contrast-enhancing and non-enhancing tumor data, and follow-up. Results Fifty-nine patients were enrolled; 58 formed the final analytic cohort after exclusion of 1 RANO-resect class 1 patient. Four-group Kaplan-Meier analyses were significant for OS (log-rank P = 0.003) and PFS (log-rank P < 0.001). In the prespecified multivariable Cox model adjusted for age, sex, CNS WHO grade, and tumor type, each 1-class increase in RANO-resect was associated with worse OS (hazard ratio, 1.68; 95% confidence interval, 1.10-2.57; P = 0.016) and PFS (hazard ratio, 1.36; 95% confidence interval, 1.01-1.82; P = 0.040). Extended models that added preoperative imaging covariates one at a time showed directionally consistent RANO-resect estimates. Conclusions Higher early postoperative MRI-based RANO-resect class was associated with worse survival in WHO 2021-defined IDH-mutant high-grade gliomas, with the most consistent signal for OS. RANO-resect may support standardized postoperative residual-burden stratification but should be interpreted alongside baseline tumor burden and should not guide treatment decisions alone.