P14.59 Rapid early progression of glioblastoma is not related to cortical/neural stem cells regions

• Published in: Neuro-oncology (Charlottesville, Va.) Vol. 23; no. Supplement_2; p. ii49
• Main Authors: Kazda, T, Lakomy, R, Selingerova, I, Pospisil, P, Hynkova, L, Belanova, R, Slampa, P
• Format: Journal Article
• Language: English
• Published: 09.09.2021
• ISSN: 1522-8517; 1523-5866
• DOI: 10.1093/neuonc/noab180.170

Abstract BACKGROUND Rapid early progression (REP) of glioblastoma after surgery observed on pre-radiotherapy MRI scan is common. Subventricular zone (SVZ) and hippocampal regions are supposed to harbor astrocyte-like neural stem cells (NSC) with tumors arising from these transformed stem cells threatening of higher risk of REP. REP is defined as a new enhancing tumor or >25% increase in enhancement before radiotherapy. Lim′s classification of initial glioblastoma location related to these NSC regions predicts invasive and multifocal tumor phenotype. Glioblastomas are classified preoperatively into four groups by the spatial relationship of the contrast-enhancing lesion with the SVZ and cortex. The aim of this retrospective single-institutional study is to evaluate the relations of this Lim classification on REP in unselected cohort of glioblastoma patients. MATERIAL AND METHODS Patients receiving radiotherapy between 2014–2017 were analyzed, 95 were evaluable. 47 patients (30.5%) were treated with the Stupp regimen. Lim1 classification (contact with cortex as well as SVZ) was presented in 74(48%) patients, Lim2 (contact with SVZ only) in 22(14.3%), Lim3 (contact with cortex only) in 50(32.5%) and Lim4 in 8(5.2%) patients. A total of 52% of patients developed REP. RESULTS Significantly better overall survival was with Stupp regimen (23.3 vs. 8.6 months, p<0.001) and without REP (18.5 vs. 10.2 months, p=0.001). There was no significant impact of time to start of radiotherapy. No significant relation between REP and Lim classification was observed. CONCLUSION The initial location is not predictive for REP. Patients experiencing REP have significantly worse overall survival and modification of their management represents an urgent unmet clinical need. Molecular and clinical biomarkers indicating an increased risk of REP are needed.Presented will also be an already published analysis of clinical factors associated with REP in glioblastoma and the effect of REP and treatment on survival outcomes. Newly, we will introduce the investigator-initiated prospective academic clinical trial (GlioMET) focused on optimization of glioblastoma radiotherapy by 11C-Methionine PET scan in patients with REP. Supported by Ministry of Health of the Czech Republic AZV, No.18-03-00469 and AZV NU20-03-00148.