The prognostic role of extent of resection (EOR) of low-grade gliomas (LGGs) is a major controversy. We designed a retrospective study to assess the influence of EOR on long-term outcomes of LGGs.

The study population (N = 216) included adults undergoing initial resection of hemispheric LGG. Region-of-interest analysis was performed to measure tumor volumes based on fluid-attenuated inversion-recovery (FLAIR) imaging.

Median preoperative and postoperative tumor volumes and EOR were 36.6 cm³ (range, 0.7 to 246.1 cm³), 3.7 cm³ (range, 0 to 197.8 cm³) and 88.0% (range, 5% to 100%), respectively. There was no operative mortality. New postoperative deficits were noted in 36 patients (17%); however, all but four had complete recovery. There were 34 deaths (16%; median follow-up, 4.4 years). Progression and malignant progression were identified in 95 (44%) and 44 (20%) cases, respectively. Patients with at least 90% EOR had 5- and 8-year overall survival (OS) rates of 97% and 91%, respectively, whereas patients with less than 90% EOR had 5- and 8-year OS rates of 76% and 60%, respectively. After adjusting each measure of tumor burden for age, Karnofsky performance score (KPS), tumor location, and tumor subtype, OS was predicted by EOR (hazard ratio [HR] = 0.972; 95% CI, 0.960 to 0.983; P < .001), log preoperative tumor volume (HR = 4.442; 95% CI, 1.601 to 12.320; P = .004), and postoperative tumor volume (HR = 1.010; 95% CI, 1.001 to 1.019; P = .03), progression-free survival was predicted by log preoperative tumor volume (HR = 2.711; 95% CI, 1.590 to 4.623; P ≤ .001) and postoperative tumor volume (HR = 1.007; 95% CI, 1.001 to 1.014; P = .035), and malignant progression-free survival was predicted by EOR (HR = 0.983; 95% CI, 0.972 to 0.995; P = .005) and log preoperative tumor volume (HR = 3.826; 95% CI, 1.632 to 8.969; P = .002).

Improved outcome among adult patients with hemispheric LGG is predicted by greater EOR.