Effect of radiation dose to the periventricular zone and subventricular zone on survival in anaplastic gliomas

Abstract

PurposeEvidence suggests a correlation of subventricular zone (SVZ) irradiation on survival. Most of the data have been analysed in glioblastoma patients. The aim of this study is to analyse the dose to the subventricular and periventricular zone and its outcomes in anaplastic gliomas.Materials and methodsA retrospective analysis of patients with anaplastic gliomas were admitted for post-chemoradiation from January 2010 to June 2016 was done from treatment records. SVZ was contoured as 5 mm expansion along the lateral margin of the lateral ventricles, and PVZ was contoured as 5 mm lateral expansion adjacent to ventricles. Dosimetric data were collected from the treatment planning system.ResultsNinety-five patients were included in the analysis. The median age was 35 years. Two- and five-year overall survival (OS) for the entire group was 84% and 54.2%, respectively. Two- and five-year progression-free survival (PFS) was 79.8% and 50.6%, respectively. Patients receiving <54 Gy to the i/l SVZ showed a significantly better PFS and OS. 5-Year OS was 72.6% in this group compared to 37% for the group receiving ≥54 Gy (p = 0.01). Five-year PFS was 69.9% in this group compared to 31.9% for the group receiving ≥54 Gy (p = 0.02). However, this was not significant in multivariate analysis.ConclusionIncreased dose to the ipsilateral SVZ does not correlate with improved survival in anaplastic gliomas. There is conflicting evidence regarding the benefit of irradiating the stem cell zones. Future studies should focus on optimizing doses to these areas to reduce detriment in neurocognition.

The Subventricular Zone, a Hideout for Adult and Pediatric High-Grade Glioma Stem Cells

“…In (136). In a prospective study including 74 GBM patients, the same team did not found any correlation between SVZ dose and PFS/OS (137).…”

“…Recently, in a retrospective study of 95 patients suffering from anaplastic gliomas, Valiyaveettil et al. reported no correlation between SVZ dose and PFS/OS in multivariate analysis ( 136 ). In a prospective study including 74 GBM patients, the same team did not found any correlation between SVZ dose and PFS/OS ( 137 ).…”

Location of Glioblastoma and its Significance in Response to Treatment

“…Radiation treatment is more cumbersome in the periventricular and subventricular zones. It has been shown that radiation doses over 54Gy do not improve, and may potentially worsen prognosis when given to GB in the periventricular zone [27]. Whether this represents increased sensitivity of the area to radiation treatment or saturation of the sensitivity of GB in this area to radiation (related to their stem cell potential, discussed earlier), is unclear.…”