Survival association of T2-FLAIR–guided tumor resection in supratentorial glioblastoma: a prospective volumetric study with threshold-based analysis FLAIR-guided resection and survival in glioblastoma

The prognostic significance of resection within the T2-FLAIR abnormality in supratentorial glioblastoma remains unclear. While maximal removal of contrast-enhancing tumor is standard practice, the survival association of resecting adjacent non-enhancing, FLAIR-abnormal tissue has not been quantitatively established. To evaluate the impact of resection extent within the T2-FLAIR abnormality zone on overall survival in patients with newly diagnosed glioblastoma. In a prospective observational cohort, we enrolled 273 adult patients with primary supratentorial glioblastoma who underwent tumor resection followed by standard chemoradiotherapy. Postoperative MRI obtained within 24 h was used to calculate volumetric extent of resection for both T1-contrast–enhancing tumor (T1-CET) and T2-FLAIR abnormality. Patients were categorized as having subtotal (≥ 78% but < 100%) or total (100%) T1-CET resection. In the total-resection group, patients were further stratified by FLAIR EOR: ≤ 25%, 26–50%, 51–75%, and > 75%. OS and recurrence patterns were compared between groups. Total T1-CET resection significantly improved OS compared to subtotal resection (15.6 vs. 10.9 months, p < 0.001), without increasing 30-day neurological complications (p = 0.694). Among patients with total T1-CET resection, OS increased across prespecified FLAIR-EOR strata (≤ 25%: 13.3 mo; 26–50%: 15.9 mo; 51–75%: 16.2 mo), with the > 75% group showing a similar median OS (16.2 mo). In multivariable models, each 10% increase in FLAIR EOR was associated with lower mortality risk (HR 0.615, 95% CI 0.540–0.700; p < 0.001). Recurrence location distributions differed across FLAIR-EOR strata, with failures more frequently classified as eloquent/periventricular versus pericavity at higher FLAIR EOR. In this prospective cohort, greater resection of T2-FLAIR abnormality beyond complete T1-CET removal was independently associated with improved survival. Within an experienced function-preserving surgical framework, these findings suggest that greater resection of T2-FLAIR abnormality may provide additional prognostic information in appropriately selected supratentorial GBM cases. They should not be interpreted as establishing a universal FLAIR-based surgical endpoint for all supratentorial GBMs.