The phenomenon of long-term survival of patients with supratentorial glioblastomas: features of complex treatment and neuroimaging data

Background. Glioblastoma is the most common primary malignant brain tumor with an extremely unfavorable prognosis. The frequency of the “longevity” phenomenon (>3 years of overall survival – OS) in this disease is 5–10 %. The reasons for the more favorable prognosis in these patients are still unclear. Aim. To compare the clinical and MRI data as well as features of complex treatment of patients with supratentorial glioblastomas among the control group (OS <2 years) and study group (with the phenomenon of “longevity”, OS >3 years). Material and methods. This study included 41 patients with hemispheric glioblastomas: 17 with the “longevity” phenomenon (study group – long-term survival (LTS), prospective set); 24 patients in the control group (retrospective set). Taking into account the average age of patients, the following MRI features were examined: tumor localization relative to the frontal lobe; invasion of deep brain structures; the ratio of contrastenhancing and non-contrast-enhancing parts of the glioma; tumor contrast intensity; localization of recurrent tumor (local / distant) in case of disease progression. Comparative analysis of complex treatment took into account the following parameters: the number of chemotherapy (ChT) courses and radiation regimens after the 1 st operation and after disease recurrence; the fact and number of repeated tumor resections after recurrence; the presence of IDH1 mutation. Results. The localization of the lesion relative to the frontal lobe, the number of affected lobes of the brain and the invasion of deep structures did not differ significantly in the examined groups. Patients of study group (LTS, prospective set) were significantly younger than the patients of the control group ( p <0.05). The tendency towards a single-lobe lesion was noted in the LTS group ( p = 0.085). The average volume of the contrast-enhancing part of the tumor (according to MRI data in the T1 mode) in patients of LTS group was 34 cm 3 , and the non-contrast-enhancing part (in the T2-FLAIR mode) was 105 cm 3 , the ratio was 1: 3 ( p >0.05). The tumor contrast intensity was 1.5 in average compared to the intact cerebral hemisphere. Among patients of LTS group, 8 patients (47 %) were re-operated due to disease recurrence, while in the control group there were no repeated operations ( p <0.05). The results of the analysis of radiation therapy after the 1 st operation were the follows: for LTS patients the median total radiation dose (TRD) was 58 (35–66) Gy, with no significant differences between the groups ( p >0.05); the number of temozolomide courses in the LTS group were 9 (6–22), while in the control group it was 6 (3–10), p <0.05. The repeated radiotherapy (RT) in different regimens was applied in the LTS group in 52 % of patients, in the control group – 0 ( p <0.05). The repeated ChT (17 (9–23) courses, mainly with bevacizumab) was applied in the LTS group in 65 % of patients, in the control group – 0 ( p <0.05). The IDH1 mutation was studied only in 15 patients: positive – in 1 (LTS group); negative – in 14 patients (7 from the control group). Conclusion . The following significant differences were revealed: patients with supratentorial glioblastomas were younger in the LTS group. The important features of the complex treatment of patients in LTS group included statistically higher frequency of repeated resections in case of recurrence (47 %) and repeated sessions of radiotherapy (RT) in various modes (52 %); significantly more aggressive and prolonged ChT (with the predominance of temozolomide in the 1 st line of treatment and bevacizumab in case of recurrence). There were no significant differences between two examined groups in tumor localization, intensity of its contrasting, the ratio of contrasted and non-contrast parts of the tumor, invasion of deep structures of the brain, involvement of functionally significant areas (FSA).