title: Increased evidence for the prognostic value of primary tumor asphericity in pretherapeutic FDG PET for risk stratification in patients with head and neck cancer.
abstract: OBJECTIVE
  In a previous study, we demonstrated the first evidence that the asphericity (ASP) of pretherapeutic FDG uptake in the primary tumor provides independent prognostic information in patients with head and neck cancer. The aim of this work was to confirm these results in an independent patient group examined at a different site.
  
  
  METHODS
  FDG-PET/CT was performed in 37 patients. The primary tumor was delineated by an automatic algorithm based on adaptive thresholding. For the resulting ROIs, the metabolically active part of the tumor (MTV), SUVmax, SUVmean, total lesion glycolysis (TLG) and ASP were computed. Univariate Cox regression with respect to progression free survival (PFS) and overall survival (OS) was performed. For survival analysis, patients were divided in groups of high and low risk according to the parameter cut-offs defined in our previous work. In a second step, the cut-offs were adjusted to the present data. Univariate and multivariate Cox regression was performed for the pooled data consisting of the current and the previously described patient group (N = 68). In multivariate Cox regression, clinically relevant parameters were included.
  
  
  RESULTS
  Univariate Cox regression using the previously published cut-off values revealed TLG (hazard ratio (HR) = 3) and ASP (HR = 3) as significant predictors for PFS. For OS MTV (HR = 2.7) and ASP (HR = 5.9) were significant predictors. Using the adjusted cutoffs MTV (HR = 2.9/3.3), TLG (HR = 3.1/3.3) and ASP (HR = 3.1/5.9) were prognostic for PFS/OS. In the pooled data, multivariate Cox regression revealed a significant prognostic value with respect to PFS/OS for MTV (HR = 2.3/2.1), SUVmax (HR = 2.1/2.5), TLG (HR = 3.5/3.6), and ASP (HR = 3.4/4.4).
  
  
  CONCLUSIONS
  Our results confirm the independent prognostic value of ASP of the pretherapeutic FDG uptake in the primary tumor in patients with head and neck cancer. Moreover, these results demonstrate that ASP can be determined unambiguously across different sites.
authors.affiliation: PET Center, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328, Dresden, Germany, hofheinz@hzdr.de.
authors.forename: Frank
authors.initials: F
authors.lastname: Hofheinz
authors.forename: Alexandr
authors.initials: A
authors.lastname: Lougovski
authors.forename: Klaus
authors.initials: K
authors.lastname: Zöphel
authors.forename: Maria
authors.initials: M
authors.lastname: Hentschel
authors.forename: Ingo G
authors.initials: IG
authors.lastname: Steffen
authors.forename: Ivayla
authors.initials: I
authors.lastname: Apostolova
authors.forename: Florian
authors.initials: F
authors.lastname: Wedel
authors.forename: Ralph
authors.initials: R
authors.lastname: Buchert
authors.forename: Michael
authors.initials: M
authors.lastname: Baumann
authors.forename: Winfried
authors.initials: W
authors.lastname: Brenner
authors.forename: Jörg
authors.initials: J
authors.lastname: Kotzerke
authors.forename: Jörg
authors.initials: J
authors.lastname: van den Hoff
mesh_terms: D000328:Adult; D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D019788:Fluorodeoxyglucose F18; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D019275:Radiopharmaceuticals; D016019:Survival Analysis; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18