The influence of maximum safe resection of glioblastoma on survival in 1229 patients: Can we do better than gross-total resection?
Authors: Li Yan Michael , Suki Dima , Hess Kenneth , Sawaya Raymond 
Published: October 2015

OBJECT
Glioblastoma multiforme (GBM) is the most common and deadliest primary brain tumor. The value of extent of resection (EOR) in improving survival in patients with GBM has been repeatedly confirmed, with more extensive resections providing added advantages. The authors reviewed the survival of patients with significant EORs and assessed the relative benefit/risk of resecting 100% of the MRI region showing contrast-enhancement with or without additional resection of the surrounding FLAIR abnormality region, and they assessed the relative benefit/risk of performing this additional resection.

METHODS
The study cohort included 1229 patients with histologically verified GBM in whom ≥ 78% resection was achieved at The University of Texas MD Anderson Cancer Center between June 1993 and December 2012. Patients with > 1 tumor and those 80 years old or older were excluded. The survival of patients having 100% removal of the contrast-enhancing tumor, with or without additional resection of the surrounding FLAIR abnormality region, was compared with that of patients undergoing 78% to < 100% EOR of the enhancing mass. Within the first subgroup, the survival durations of patients with and without resection of the surrounding FLAIR abnormality were subsequently compared. The data on patients and their tumor characteristics were collected prospectively. The incidence of 30-day postoperative complications (overall and neurological) was noted.

RESULTS
Complete resection of the T1 contrast-enhancing tumor volume was achieved in 876 patients (71%). The median survival time for these patients (15.2 months) was significantly longer than that for patients undergoing less than complete resection (9.8 months; p < 0.001). This survival advantage was achieved without an increase in the risk of overall or neurological postoperative deficits and after correcting for established prognostic factors including age, Karnofsky Performance Scale score, preoperative contrast-enhancing tumor volume, presence of cyst, and prior treatment status (HR 1.53, 95% CI 1.33–1.77, p < 0.001). The effect remained essentially unchanged when data from previously treated and previously untreated groups of patients were analyzed separately. Additional analyses showed that the resection of ≥ 53.21% of the surrounding FLAIR abnormality beyond the 100% contrast-enhancing resection was associated with a significant prolongation of survival compared with that following less extensive resections (median survival times 20.7 and 15.5 months, respectively; p < 0.001). In the multivariate analysis, the previously treated group with < 53.21% resection had significantly shorter survival than the 3 other groups (that is, previously treated patients who underwent FLAIR resection ≥ 53.21%, previously untreated patients who underwent FLAIR resection < 53.21%, and previously untreated patients who underwent FLAIR resection ≥ 53.21%); the previously untreated group with ≥ 53.21% resection had the longest survival.

CONCLUSIONS
What is believed to be the largest single-center series of GBM patients with extensive tumor resections, this study supports the established association between EOR and survival and presents additional data that pushing the boundary of a conventional 100% resection by the additional removal of a significant portion of the FLAIR abnormality region, when safely feasible, may result in the prolongation of survival without significant increases in overall or neurological postoperative morbidity. Additional supportive evidence is warranted.