Results of treatment of patients with diffuse adult type glioma without mutation in the IDH gene

Abstract

Objective. To establish the prognostic value of the malignancy grading of adult-type diffuse gliomas in the absence of a mutation in the IDH gene (IDHwt).

Materials and methods. The retrospective study included 639 patients with a morphologically established diagnosis of diffuse glioma of the adult type of the brain with varying malignancy grading (grade 2—4) and IDHwt, treated in 2017— 2021. In 67 (10,5 %) patients, the malignancy grading of the tumor corresponded to grade 2, in 59 (9,2 %) — grade 3 and 513 (80,3 %) — grade 4 (glioblastoma, GBM).

Results. The results of treatment of patients with diffuse adult gliomas grade 2 (median overall survival (OS) not reached, 5-year OS 56,0±6,9 %) were statistically significantly better compared with patients with grade 3 (median and 5-year OS 11,5±2,8 months and 9,5±4,9 %; p<0,001) and grade 4 (GBM) (median and 5-year OS 9,4±0,6 months and 2,1±1,0 %; p<0,001). There were no statistically significant differences in OS between patients with grade 3 and grade 4 GBM) (p=0,638).

Conclusion. Inclusion of patients with diffuse adult-type gliomas with grade 2 into the nosological type «glioblastoma» only on the basis of IDHwt is inappropriate due to the higher OS in this subgroup of tumors. In the case of planning clinical trials and including patients with diffuse adult-type gliomas grade 2—3 with IDHwt, additional molecular genetic studies must be carried out (determining EGFR amplification, TERTp mutation, acquisition of chromosome 7 and loss of chromosome 10 ) in order to determine the possibility of classifying these tumors into the category «glioblastoma».