Recurrence pattern after [(18)F]Fluoroethyltyrosine-Positron Emission Tomography-guided radiotherapy for high-grade glioma: A prospective study

Purpose To assess the failure pattern observed. after (18)F fluoroethyltyrosine (FET) planning after chemo- and radiotherapy (RT) for high-grade glioma; Methods: All patients underwent prospectively RT planning using morphological gross tumour volumes (GTVs) and biological tumour volumes (BTVs) The post-treatment recurrence tumour volumes (RTVs) of 10 patients were transferred on their CT planning First, failure patterns were defined in terms of percentage of RTV located outside the GTV and BTV. Second, the location of the RTV with respect to the delivered dose distribution was assessed using the RTV's DVHs. Recurrences with >95% of their volume within 95% isodose line were considered as central recurrences Finally, the relationship between survival and GTV( BTV mismatches was assessed Results. The median percentages of RTV outside the GTV and BTV were 41.8% (range, 10.5-92.4) and 62.8% (range, 34.2-81.1), respectively. The majority of recurrences (90%) were centrally located. Using a composite target volume planning formalists, the degree of GTV and BTV mismatch did not correlate with survivorship. Conclusions: The observed failure pattern after FET-PET planning and chemo-RT is primarily central. The target mismatch-survival data suggest that using FET-PET planning may counteract the possibility of BTV-related progression, which may have a detrimental effect on survival. (C) 2009 Elsevier Ireland Ltd All rights reserved Radiotherapy and Oncology 93 (2009) 586-592