Abstract 768P
Background
Despite best management strategies glioblastoma (GBM) survival remains poor. Cancer stem cells may be possible in initiation and recurrence of GBM. They are believed to originate from stem cells in the subventricular zone (SVZ). In this study, we retrospectively collected the data using institutional medical records and analyzed the relationship of SVZ dose to survival.
Methods
We included 48 GBM patients treated between 2017 to March 2024. Post tumor resection, 34 patients received radiotherapy to dose 59.4-60 Gray in 30 fractions and 14 received 40 Gray in 15 fractions with concurrent and adjuvant six cycles of temozolomide. Ipsilateral and contralateral SVZ were delineated as 5 mm along lateral wall of lateral ventricles. The effect of high SVZ dose on OS and PFS were determined using Log rank test, Kaplan Meier survival curve and Cox proportional hazard models. The variables for multivariate analysis were pre-radiotherapy KPS, ipsilateral and contralateral SVZ dose, tumor brain volume ratio and tumor size group.
Results
The mean age group 43 years, pre-radiotherapy KPS < 80 was in 24 (50%). Mean ipsilateral SVZ max dose, contralateral SVZ max dose and mean tumor brain volume ratio were 54.47 Gray, 49.53 Gray and 31.52 % respectively. The mean OS and PFS were 16.2 and 13.8 months. Median OS was significantly more in tumor brain volume ratio < 29 % (31.7 vs 14.2 months), ipsilateral SVZ max dose >49 Gray (26.3 vs 15.9 months) and contralateral SVZ max dose >49 Gray (26.3 vs 14.9 months). Median PFS was significantly more in tumor size < 4 cm (26.3 vs 14.9 months), ipsilateral SVZ max dose >49 Gray (21.8 vs 7.4 months), contralateral SVZ max dose >49 Gray (23.2 vs 14.2 months). On multivariate analysis, pre-radiotherapy KPS >80, ipsilateral SVZ max dose >49 Gray and tumor brain volume ratio < 29 % remained a statistically significant predictor for improved OS. While pre-radiotherapy KPS >80, tumor size < 4cm, ipsilateral and contralateral SVZ max dose > 49 Gray were statistically significant predictor for improved PFS.
Conclusions
High Ipsilateral SVZ max dose (>49 Gray) and tumor brain ratio < 29 % are associated with better OS. High Ipsilateral and contralateral SVZ max dose (>49 Gray) is associated with better PFS in GBM patients.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.