Margin reduction in radiotherapy for glioblastoma through 18F-fluoroethyltyrosine PET? – A recurrence pattern analysis

• Published in: Radiotherapy and oncology 2020-04, Vol.145, p.49-55
• Main Authors: Fleischmann, Daniel F., Unterrainer, Marcus, Schön, Rudolph, Corradini, Stefanie, Maihöfer, Cornelius, Bartenstein, Peter, Belka, Claus, Albert, Nathalie L., Niyazi, Maximilian
• Format: Article
• Language: English
• Subjects: 18F FET PET; Glioblastoma; Margin reduction; Recurrence pattern
• ISSN: 0167-8140; 1879-0887
• DOI: 10.1016/j.radonc.2019.12.005

•Margin reduction through 18F-FET PET prior to primary radiochemotherapy.•PET-MRGTVs with 15 mm CTV margins versus MRGTVs with 20 mm CTV margins.•Significantly smaller PET-based target volumes with comparable recurrence pattern.•Basis for prospective studies on 18F-FET PET based margin adjustments. 18F-fluoroethyltyrosine (18F-FET) PET is increasingly used in radiation treatment planning for the primary treatment of glioblastoma (GBM) patients additionally to contrast-enhanced MRI. To answer the question, whether a margin reduction in the primary treatment setting could be achieved through 18F-FET PET imaging, a recurrence pattern analysis was performed. GBM patients undergoing 18F-FET PET examination before primary radiochemotherapy from 05/2009 to 11/2014 were included into the recurrence pattern analysis. Biological tumour volumes were semi-automatically created and fused with MR-based gross tumour volumes (MRGTVs). The pattern of recurrence was examined for MRGTVs and for PET-MRGTVs. The minimal margin including all recurrent tumour sites was assessed by gradual expansion of the PET-MRGTVs and MRGTVs until inclusion of all contrast-enhancing areas at recurrence. 36 GBM patients were included to the analysis. The minimal margin including all contrast enhancing tumour at recurrence was significantly smaller for the PET-MRGTVs compared to the MRGTVs (median 12.5 mm vs. 16.5 mm; p