Clinical characteristics and prognostic factors of insular glioblastomas

Abstract

Objective To explore the clinical characteristics and prognostic factors of insular glioblastomas. Methods Clinical data of 44 patients with insular glioblastomas in Chinese Glioma Genome Atlas(CGGA) databases from July 2006 to June 2013 were evaluated. All patients underwent tumor resection. Among them, 27 underwent adjuvant radiochemotherapy and 17 underwent no postoperative adjuvant therapy. Progression-free survival (PFS) and overall survival (OS) of all patients were analyzed by Kaplan-Meier method. Furthermore, multivariate Cox regression analysis was used to investigate the prognostic clinical factors. Results In a total of 44 patients, 33 (75.0%) had a history of epileptic seizure, 11 (25.0%) had isocitrate dehydrogenase 1 (IDH1) mutation, 19 (43.2%) had O6-methy-lguanine-DNA-methyltransferase (MGMT) methylation, and 42 (95.5%) had tumor enhancement.Based on Yasargil′s classification, there were type 3A in 2 cases, type 3B in 27 cases and type 5A/B in 15 cases. Based on Saito′s classification, there were 2 cases confined to the insular cortex, 9 cases with invasion to the frontal lobe via the anterior circumferential sulcus, 16 cases with invasion to the temporal lobe via the lower circumferential sulcus, and 17 cases with invasion to multiple directions via more than 2 circumferential sulci. Based on Moshe′s classification, there were 35 cases with envelopment or invasion of the lenticulostriate artery, while no invasion was reported in the remaining 9 cases. Based on the putamen classification, there were 38 cases with various degrees of putamen invasion, and the remaining 6 cases had no involvement of the putamen. Kaplan-Meier curve showed that the median PFS of all patients was 278 d and the median OS was 435 d. Multivariate Cox regression analysis showed that tumor volume < median (HR = 0.390, 95% CI: 0.189-0.802, P=0.011), IDH1 mutation (HR=0.391, 95% CI: 0.175-0.876, P=0.023) and postoperative radiochemotherapy (HR=0.346, 95% CI: 0.162-0.738, P=0.006) were independent protective factors for PFS. However, MGMT methylation (HR=0.371, 95% CI: 0.181-0.758, P=0.007), tumor resection degree ≥90% (HR=0.412, 95% CI: 0.194-0.875, P=0.021) and postoperative radiochemotherapy (HR=0.347, 95% CI: 0.170-0.708, P=0.004) were independent protective factors for OS. Conclusions Clinical characteristics of insula glioblastomas include relatively lower incidence, stronger invasiveness, lower total resection ratio and poorer prognosis. Maximum resection and standard postoperative radiochemotherapy may lead to a better outcome. Key words: Glioblastoma; Insula; Prognosis; Multivariate analysis