The benefit of early surgery on overall survival in incidental low-grade glioma patients: A multicenter study

Abstract

Background: The role of surgery for incidentally discovered diffuse incidental low-grade gliomas (iLGGs) is debatable and poorly documented in current literature.

Objective: The aim was to identify factors that influence survival for patients that underwent surgical resection of iLGGs in a large multicenter population.

Methods: Clinical, radiological, and surgical data were retrospectively analyzed in 267 patients operated for iLGG from 4 neurosurgical Centers. Univariate and multivariate analyses were performed to identify predictors of overall survival (OS) and tumor recurrence (TR).

Results: The OS rate was 92.41%. The 5- and 10-year estimated OS rates were 98.09% and 93.2%, respectively. OS was significantly longer for patients with a lower preoperative tumor volume (P = .001) and higher extent of resection (EOR) (P = .037), regardless the WHO-defined molecular class (P = .2). In the final model, OS was influenced only by the preoperative tumor volume (P = .006), while TR by early surgery (P = .028). A negative association was found between preoperative tumor volumes and EOR (rs = -0.44, P < .001). The median preoperative tumor volume was 15 cm3. The median EOR was 95%. Total or supratotal resection of T2-FLAIR abnormality was achieved in 61.62% of cases. Second surgery was performed in 26.22%. The median time between surgeries was 5.5 years. Histological evolution to high-grade glioma was detected in 22.85% of cases (16/70). Permanent mild deficits were observed in 3.08% of cases.

Conclusions: This multicenter study confirms the results of previous studies investigating surgical management of iLGGs and thereby strengthens the evidence in favor of early surgery for these lesions.

Keywords: brain mapping; incidental findings; low-grade gliomas; molecular pattern; of resection.

Fig. 1

(A) Graph showing the negative association between preoperative tumor volumes and EOR achieved (rs = −0.44, P < .001). Higher preoperative tumor volume value suggests a greater propensity of the tumor to have a diffuse growing pattern and consequently to be less resectable. (B) OS in iLGGs stratified according to preoperative tumor volume (HR = 1.02; 95% CI = 1.01-1.03; P = .001). (C) OS in iLGGs stratified according to the EOR (HR = 0.97; 95% CI = 0.94-1.0; P = .037). No death event occurred in patients with supratotal resection. (D) OS in iLGGs in accordance with the EOR cutoff value able to stratify high- and low-risk OS groups (HR = 4.09; 95% CI = 1.41-11.9; P = .01). (E) OS stratified according to postoperative RTV (HR = 2.93 [95% CI 1.00-8.60]; P = .05). (F) OS stratified according to WHO-defined categories. No deaths occurred among patients belonging to IDH-wt subgroup. No survival benefit was observed between IDH-mt iLGGs and IDH-mt/1p19q codel iLGGs (P = .2; HR = 2; 95% CI = 0.74-5.43). Abbreviations: CI, confidence interval; EOR, extent of resection; HR, hazard ratio; IDH, isocitrate dehydrogenase; iLGGs, incidental low-grade gliomas; OS, overall survival; RTV, residual tumor volume.