Rt-8 Post-Irradiation Course of Gliomas of Thalamus and Brainstem

Abstract

Objective We retrospectively reviewed the post-irradiation course of cases treated with radiotherapy for the gliomas involving thalamus or brainstem. Methods Thirty-seven gliomas involving thalamus or brainstem treated with radiotherapy from 2007 to 2021 in our hospital were included. Median age was 47 (19-79) years, and KPS at the start of irradiation was 80% or less in 26 cases. Tumor localization was thalamus only/brainstem only/both thalamus and brainstem for 20/9/8 cases. Two cases did not undergo biopsy, and the others underwent surgery before irradiation. Two cases underwent partial excision of the lesion near the thalamus, 6 cases underwent partial excision from other than the thalamus-brainstem, and 27 cases underwent biopsy only. The pathological diagnosis based on the WHO classification at the time of surgery was glioblastoma (GBM) in 8 cases, high-grade glioma other than glioblastoma (HGG) in 23 cases (including 9 cases of diffuse midline glioma K27M), and low-grade glioma (LGG) in 6 cases. Results Median observation period was 16(2-66) months. Median PFS/median OS/5-year OS rate were 13 months/25 months/20% in all 37 cases. Median PFS was 66/18/7 months for LGG/ HGG/ GBM, and 5-year OS was 75/16/15%. Symptomatic cerebral edema associated with tumor growth was observed in one GBM 9 months after irradiation. In HGG, 7/23 cases underwent the VP shunting before irradiation, and one case who underwent ventriculostomy before irradiation had a VP shunting created for worsening hydrocephalus 3 months after irradiation. In one case of GBM, a VP shunt was created immediately after surgery. Conclusions Compared to the past reports of gliomas, it was suggested that the localization in thalamic brainstem was a factor for a worse prognosis in HGG.