Article
Identification of 18FET-PET time-to-peak as a prognostic marker specifically in IDH1/2 mutant diffuse astrocytoma
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Published: | June 9, 2017 |
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Objective: Stratification of glial tumors according to IDH1/2 mutation and 1p/19q co-deletion status has gained major importance in the new WHO classification and guides current clinical decision making. Parameters derived from 18FET-PET uptake dynamics such as minimal time-to-peak (TTPmin) analysis allow discrimination between different prognostic glioma subgroups, too. The present study aimed at exploring whether TTPmin analysis provides prognostic information beyond the new WHO classification.
Methods: Three-hundred patients with newly diagnosed WHO 2007 grade II-IV gliomas with 18FET-PET imaging at diagnosis were grouped according to IDH1/2 mutation and 1p/19q co-deletion status into 3 subgroups (IDH1/2 mut/1p/19q co-del; IDH1/2 mut/1p/19q non co-del and IDH1/2 wildtype). Clinical and imaging factors such as age, Karnofsky performance score, treatment, TTP analysis, biological tumor volume (BTV) and tumor-to-brain ratio (TBR) were analyzed with regard to progression-free and overall survival (PFS and OS) via univariate and multivariate regression analysis.
Results: PFS and OS were longest in the IDH1/2 mut/1p/19q co-del subgroup followed by IDH1/2 mut/1p/19q non co-del and IDH1/2 wt patients (p<0.0001). Further, outcome stratified by TTPmin with a cut-off of 17.5 minutes revealed significantly longer PFS and OS in patients with TTPmin >17.5 minutes (p<0.0001 for PFS and OS). Lower TBRmax values or the absence of 18FET-uptake were also associated with favorable outcome in the entire group. Longer median TTPmin times were associated with improved outcome specifically in the IDH1/2 mut/1p/19q non co-del group, but neither in the IDH1/2 mut/1p/19q co-del nor in the IDH1/2 wt group.
Conclusion: 18FET-PET-derived dynamic analysis defines prognostically distinct sub-groups of IDH1/2 mutant/ 1p/19q-non-co-deleted gliomas which cannot be distinguished as yet by molecular marker analysis.