Is FLAIRectomy Directly Correlated with Prolonged Survival in Glioblastoma? A Prospective National Multicenter Study on Correlation Between Extent of Tumor Resection and Clinical Outcome

Neurosurgery 97:489–500, 2025

This multicenter prospective study shows that the extent of FLAIRectomy (resection of FLAIR-positive areas) in glioblastoma is a stronger predictor of survival than traditional resection, with higher EOFR significantly improving progression-free and overall survival, especially in IDH-mutant tumors, without increasing neurological complications.

• FLAIRectomy, or resection of FLAIR-MRI hyperintense regions beyond the contrast-enhancing tumor, was studied in a prospective multicenter cohort of 150 glioblastoma patients.

• A higher extent of FLAIR resection (EOFR) was associated with significantly improved overall survival (OS) and progression-free survival (PFS), more so than resection of contrast-enhancing tumor alone.

• Each 1% increase in EOFR correlated with a 6.8% reduction in mortality risk for IDH-wildtype and 12.1% for IDH-mutant tumors.

• Mean OS was 28.4 months and mean PFS was 16.3 months in the study cohort.

• IDH1 mutation status was also associated with longer survival, but EOFR remained an independent predictor after adjustment.

• AI analysis confirmed that patients with higher EOFR clustered with longer survival.

• Neurological safety was addressed with intraoperative neuromonitoring and careful planning; permanent deficits occurred in 9/150 patients.

• The study concludes that FLAIR-based supramarginal resection may be a more reliable predictor of survival in glioblastoma than conventional imaging-guided resection.

Influence of supramarginal resection on survival outcomes after gross-total resection of IDH–wild-type glioblastoma

J Neurosurg 136:1–8, 2022

The authors’ goal was to use a multicenter, observational cohort study to determine whether supramarginal resection (SMR) of FLAIR-hyperintense tumor beyond the contrast-enhanced (CE) area influences the overall survival (OS) of patients with isocitrate dehydrogenase–wild-type (IDH-wt) glioblastoma after gross-total resection (GTR).

METHODS The medical records of 888 patients aged ≥ 18 years who underwent resection of GBM between January 2011 and December 2017 were reviewed. Volumetric measurements of the CE tumor and surrounding FLAIR-hyperintense tumor were performed, clinical variables were obtained, and associations with OS were analyzed.

RESULTS In total, 101 patients with newly diagnosed IDH-wt GBM who underwent GTR of the CE tumor met the inclusion criteria. In multivariate analysis, age ≥ 65 years (HR 1.97; 95% CI 1.01–2.56; p < 0.001) and contact with the lateral ventricles (HR 1.59; 95% CI 1.13–1.78; p = 0.025) were associated with shorter OS, but preoperative Karnofsky Performance Status ≥ 70 (HR 0.47; 95% CI 0.27–0.89; p = 0.006), MGMT promotor methylation (HR 0.63; 95% CI 0.52–0.99; p = 0.044), and increased percentage of SMR (HR 0.99; 95% CI 0.98–0.99; p = 0.02) were associated with longer OS. Finally, 20% SMR was the minimum percentage associated with beneficial OS (HR 0.56; 95% CI 0.35–0.89; p = 0.01), but > 60% SMR had no significant influence (HR 0.74; 95% CI 0.45–1.21; p = 0.234).

CONCLUSIONS SMR is associated with improved OS in patients with IDH-wt GBM who undergo GTR of CE tumor. At least 20% SMR of the CE tumor was associated with beneficial OS, but greater than 60% SMR had no significant influence on OS.

FLAIR signal increase of the fluid within the resection cavity after glioma surgery: generally valid as early recurrence marker?

J Neurosurg 127:417–425, 2017

Recent studies have indicated that a signal intensity increase of the fluid within the resection cavity on FLAIR images may predict tumor recurrence after glioma surgery. The aim of this study was to assess the increase in FLAIR signal intensity in a large patient cohort and in subgroups to assess its prognostic value for early tumor recurrence in glioma patients.

METHODS A total of 212 patients (213 cases) who had undergone surgery for an intracranial glioma (WHO Grade IV [n = 103], WHO Grade III [n = 57], and WHO Grade II [n = 53]) were included in this retrospective study. FLAIR signal within the resection cavity at the time of tumor recurrence/last contact and on the previous MRI study was assessed qualitatively and quantitatively. Appearance of FLAIR signal increase was studied over time using Kaplan-Meier estimates in subgroups.

RESULTS Patients with WHO Grade II glioma and connection of the resection cavity to CSF who did not undergo radiotherapy did not regularly develop this sign and were excluded from further analysis. For the remaining 87 cases, FLAIR signal intensity increase was observed in 27 cases. Recurrent disease was found in 26 of these 27 cases, resulting in a specificity of 80.0%, a sensitivity of 31.7%, and positive and negative predictive values of 96.3% and 6.7%, respectively. In 4 cases this sign had been observed prior (range 2.8–8.5 months) to tumor recurrence defined by standard criteria. Quantitative analysis underlined the results of qualitative analysis, but it did not add a diagnostic value.

CONCLUSIONS Signal intensity increase of the fluid within the resection cavity on FLAIR images is a rare but highly specific and early sign for tumor recurrence/tumor progression in completely and incompletely resected high-grade glioma without connection of the resection cavity to CSF and with radiotherapy.