Multimodal techniques for maximal safe resection of IDH-mutant low-grade glioma involving corpus callosum, a retrospective study and prognosis analysis

The IDH-mutant low-grade glioma (LGG) involving corpus callosum (ccLGG) is a rare type of LGG which has a poorer prognosis. To evaluate the efficacy of multimodal techniques (comprising neuronavigation, intraoperative MRI, and neuromonitoring) compared with the conventional approach guided solely by neuronavigation in the resection of IDH-mutant ccLGG, and to identify prognostic factors of ccLGG.

The IDH-mutant ccLGG cases that received resection in our center between 2014 and 2022 were collected and reviewed retrospectively. Comparisons were made between the multimodal and conventional groups regarding patient demographics, tumor characteristics, extent of resection (EOR), neurological function, Karnofsky Performance Status (KPS), progression-free survival (PFS), and overall survival (OS). Both univariate and multivariate analysis were employed to assess potential prognostic factors.

Ultimately, 64 patients in the multimodal group and 34 in the conventional group were enrolled. Compared with the conventional group, the multimodal group achieved a significantly higher median EOR (100% vs. 93.55%, P = 0.001) and a greater gross total resection (GTR) rate (62.5% vs. 35.3%, P = 0.010). No significant differences were observed in postoperative neurological function or KPS between the two groups at any of the time points assessed. Compared with the conventional group, the multimodal group demonstrated significantly longer median PFS (78.5 vs. 48.1 months, P = 0.010) and OS (106.1 vs. 66.9 months, P = 0.009). Non-butterfly ccLGG, less tumor volume, genu invasion of CC (compared to splenium invasion), less volume of CC invasion, higher EOR, longer chemotherapy cycles of Temozolomide (TMZ), higher KPS on 3 months and MGMT methylation were positive factors for PFS of ccLGG. While four factors were associated with the longer OS of ccLGG, including genu of CC invasion compared to both genu and body invasion of CC, higher EOR, longer TMZ cycles and MGMT methylation.

Multimodal techniques are useful for achieving maximal safe resection and better prognosis of ccLGG. As higher EOR independently predicts improved survival in IDH-mutant ccLGG, maximal safe resection should be suggested and achieved by appropriate means tailored to available resources. The postoperative chemotherapy should also be recommended to patients with high risks. While whether postoperative radiotherapy should be performed should consider and balance many factors.