Prospective study to assess the survival outcomes of planned irradiation of ipsilateral subventricular and periventricular zones in glioblastoma

Abstract

Purpose/objective(s): Retrospective evidence suggests that the irradiation of stem cells in the periventricular zone (PVZ), specifically the subventricular zone (SVZ), to higher doses may be associated with improved outcomes. Materials/methods: This was a prospective study, done from 2012 to 2017 in glioblastoma patients to assess the efficacy of planned irradiation of ipsilateral PVZ and SVZ on survival outcomes. The clinical target volume included the tumour bed with a 1.5-2 cm margin, perilesional oedema and was expanded to encompass the ipsilateral PVZ (5 mm lateral expansion adjacent to the ventricles, including the SVZ, which was a 5 mm expansion lateral to lateral ventricle). The ipsilateral PVZ was planned to receive a dose of ≥50 Gy. Results: 89 patients were recruited of which 74 patients were available for the analysis. Median age was 48 years. Mean doses to ipsilateral PVZ and SVZ were 56.2 and 55.1Gy, respectively. Median overall survival in the entire group was 13 months. There was no significant correlation between survival and doses to ipsilateral, contralateral, or bilateral PVZ and SVZ. Median survival was 16, 12 and 6 months for Eastern Cooperative Oncology Group (ECOG) PS 1, 2 and 3, respectively (p = 0.05). Conclusion: Planned irradiation of potential stem cell niches in the ipsilateral cerebral hemisphere did not result in improved survival as suggested by retrospective studies. Doses to contralateral or bilateral PVZ or SVZ also did not influence survival.

Update of the EPTN atlas for CT- and MR-based contouring in Neuro-Oncology

“…This is possibly due to the lower vascular supply in these areas as well as to variability in relative biological effectiveness (RBE) when using particle therapy [9][10][11][12]25]. In addition, the innermost region of the PVS, known as subventricular zone, constitutes a major neural stem cells niche and is associated with gliomagenesis [26,27]. Co-registration with T1-weighted MRI is recommended for delineation.…”

The Role of Subventricular Zone Irradiation in High-Grade Gliomas – a Narrative Review

“…The first prospective clinical study investigating the irradiation of NSC niches in GBM was conducted on 74 patients who underwent total surgical resection followed by radiotherapy and chemotherapy (33). The CTV included the ipsilateral periventricular zone (PVZ), defined as a 5 mm expansion all around the lateral ventricles, and it included the SVZ, defined as a 5 mm lateral expansion of the lateral ventricles.…”

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

“…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 ). Finally, in a short prospective study of 30 GBM patients, the sparing irradiation of neurogenic niches, including SVZ, did not modify PFS or OS in comparison to a matched historical control ( 139 ).…”