ESTRO 2024 - Abstract Book

S965

Clinical - CNS

ESTRO 2024

3099

Digital Poster

Single center radiation plan analysis of glioblastoma patients treated according to CeTeG protocol

Sebastian H Maier 1,2 , Laura Gajdi 1 , Alexander Nitschmann 1 , Vasiliki Anagnostatou 1 , Sylvia Garny 1 , Daniel F Fleischmann 1,3,4 , Stefanie Corradini 1 , Claus Belka 1,2,4 , Stephan Schönecker 1,2 1 LMU University Hospital, Department of Radiation Oncology, Munich, Germany. 2 Bavarian Cancer Research Center, (BZKF), Munich, Germany. 3 German Cancer Consortium, (DKTK), Munich, Germany. 4 German Cancer Research Center, (DKFZ), Heidelberg, Germany

Purpose/Objective:

In the CeTeG/NOA-09 trial 1 , the combination therapy of CCNU and temozolomide to radiotherapy significantly improved survival in MGMT promoter methylated glioblastoma patients compared to temozolomide and radiation alone (48.1 vs. 31.4 months). We analyzed real-world data from patients treated with this regimen, focusing on patient outcomes and radiation plans.

Material/Methods:

In this retrospective study, we systematically gathered clinical data and radiation plans from patients who underwent treatment following the CeTeG protocol at our institution over an 11-year period. The collected plan data were uploaded into ProKnow (Elekta, Stockholm, Sweden). Our investigation involved survival analyses, facilitating a comprehensive evaluation of the radiation plans employed in our study cohort.

Results:

Twenty-five patients (12 female, 13 male) were included. The median age at radiotherapy was 56 years (28-68). 6 month survival was 88%, the 18-month survival 66%. 5 plans were performed as 3D plans, 20 by VMAT technique. Substantial differences are evident in the plan comparison, for example, the median volume of the GTV is 39.24cc (range 2.22-156.13) the median volume of CTV is 235.82cc (97.96-314.84) and 334.37cc (136.15-448.96) for PTV. Furthermore, the median V40 for brain-GTV is 27.12% (11.78-42.83%), while the median D max at the chiasm is 48.32 Gy (2.59-53.54 Gy). There were also differences in the exposure of the remaining brain (brain-GTV) between the 3D plans and the VMAT plans. For example, median V40 was 36.32% (29.38-39.19%) for the 3D plans, but only 25.66% (11.78-42.83%) for the VMAT plans showing the higher conformality.

Conclusion:

Overall, our investigation of real-world data from glioblastoma patients treated with CCNU and temozolomide in line with the CeTeG protocol demonstrates survival outcomes comparable to those presented in the initial trial.