Feasibility of hippocampus-sparing VMAT for newly diagnosed glioblastoma treated by chemoradiation: pattern of failure analysis

Chan Woo Wee,Jung Ho Han,Yu Jung Kim,In Ah Kim,Chae-Yong Kim,Kyung Su Kim

doi:10.1186/s13014-020-01552-0

Chan Woo Wee, Jung Ho Han + Show 4 more

Open Access

https://doi.org/10.1186/s13014-020-01552-0

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Abstract

BackgroundTo identify the pattern of failure and oncological safety of hippocampus (HC)-sparing IMRT (HSRT) in newly diagnosed glioblastoma (GBM) patients.Materials and methodsEighty-two GBM patients treated with temozolomide-based chemoradiation using HSRT between 2014 and 2018 were retrospectively reviewed. HSRT consisted of a sparing of Dmax of the contralateral HC < 17 Gy. Fifteen patients were unable to achieve the dose-constraints for adequate target coverage. The dose to ipsilateral HC was kept as low as possible. The pattern of failure was investigated, focusing on the area in the vicinity of the spared HC (organ and + 1 cm area). The median HSRT dose was 60 Gy in 30 fractions.ResultsThe median follow-up for survivors was 11.7 months. The median progression-free and overall survival were 9.7 and 23.5 months, respectively. Six (7.3%) and eight (9.8%) patients eventually demonstrated progressive disease at the contralateral HC and HC + 1 cm, respectively. The 12-month contralateral HC and HC + 1 cm failure-free rate were 97.2 and 93.4%, respectively. However, no patient (0%) and two patients (2.4%) showed failure at contralateral HC and HC + 1 cm at initial progression, respectively. The dominant pattern of failure at the contralateral HC was by subependymal seeding (66.7%).ConclusionThe incidence of failure at the contralateral HC and HC + 1 cm is very low and mostly accompanied by disseminated disease progression after HSRT. Since HSRT does not compromise oncological outcomes, it could be considered especially for GBM patients who are expected to have favorable survival outcomes.

Highlights

Glioblastoma (GBM), the most common brain cancer in adults, is treated by radiotherapy (RT) plus concurrentBrain RT is well-known to be related with deterioration of neurocognitive functions
We have previously reported that contralateral HC can be effectively spared in patients with primary brain tumors via volumetricmodulated arc therapy (VMAT) to preserve the verbal memory function [18]
The median dose to 100% volume (D100%) and Dmax of the contralateral HC (cHC) were 6.71 Gy and 16.10 Gy, respectively

Summary

Introduction

Glioblastoma (GBM), the most common brain cancer in adults, is treated by radiotherapy (RT) plus concurrentBrain RT is well-known to be related with deterioration of neurocognitive functions. In the treatment of brain metastasis, hippocampus-sparing whole brain RT was proven to be effective in the preserving verbal memory function in a recent clinical trial [6]. Hippocampus-sparing RT (HSRT) was evaluated in primary brain tumors, using sophisticated RT techniques, especially intensitymodulated RT [7,8,9,10,11,12,13,14,15,16,17]. We have previously reported that contralateral HC (cHC) can be effectively spared in patients with primary brain tumors via volumetricmodulated arc therapy (VMAT) to preserve the verbal memory function [18]. To identify the pattern of failure and oncological safety of hippocampus (HC)-sparing IMRT (HSRT) in newly diagnosed glioblastoma (GBM) patients

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