title: 18F-FDG PET-CT performed before and during radiation therapy of head and neck squamous cell carcinoma: Are they independent or complementary to each other?
abstract: BACKGROUND
  The aims of this study are to evaluate the prognostic value of metabolic parameters derived from (18) F-FDG PET-CT performed before definitive radiation therapy (RT) (prePET) in patients with mucosal primary head and neck squamous cell carcinoma (MPHNSCC) and to assess the additive prognostic values of FDG PET-CT performed during RT (iPET).
  
  
  METHODS
  One hundred patients with MPHNSCC treated with radical RT underwent staging prePET and iPET performed during the third week of treatment. The maximum standardized uptake value (SUVmax ), metabolic tumour volume (MTV) and total lesional glycolysis (TLG) of primary tumour were analysed for both prePET and iPET, and results were correlated with loco-regional recurrence-free survival (LRFS), disease-free survival (DFS), metastatic failure-free survival (MFFS) and overall survival (OS), using Kaplan-Meier analysis. Optimal cut-offs (OC) for prePET and iPET were derived from Receiver Operating Characteristic curves. Patients with metabolic parameters above/below the individual OC of prePET as well as iPET (i.e. combined prePET and iPET (comPET)) were evaluated against their outcomes.
  
  
  RESULTS
  Median age was 61 years (range 39-81), median follow-up of 20 months (range 4-70, mean 27), and AJCC 7th Edition clinical stage II, III and IV were 8, 24 and 68 patients respectively. Metabolic values below individual OC in comPET were found to be associated with statistically significant improvements (P < 0.05) in DFS, LRFS and OS. In addition, patients with SUVmax above the OC in comPET were associated with worse MFFS (P = 0.011) and confirmed on both univariate (P = 0.019) and multivariate analyses (P = 0.04).
  
  
  CONCLUSIONS
  Addition of iPET significantly improves the prognostic values of all three metabolic parameters and can potentially be used in future adaptive local and systemic therapy trials.
authors: Cancer Therapy Centre, Liverpool Hospital, Liverpool, New South Wales, Australia.|University of New South Wales, Liverpool, New South Wales, Australia.|Ingham Institute of Applied Medical Research, Liverpool, New South Wales, Australia.
authors: Myo
authors: M
authors: Min
authors: University of New South Wales, Liverpool, New South Wales, Australia.|Department of Nuclear Medicine and PET, Liverpool Hospital, Liverpool, New South Wales, Australia.|University of Western Sydney, Liverpool, New South Wales, Australia.
authors: Peter
authors: P
authors: Lin
authors: Cancer Therapy Centre, Liverpool Hospital, Liverpool, New South Wales, Australia.|University of New South Wales, Liverpool, New South Wales, Australia.
authors: Mark
authors: M
authors: Lee
authors: University of New South Wales, Liverpool, New South Wales, Australia.|Department of Nuclear Medicine and PET, Liverpool Hospital, Liverpool, New South Wales, Australia.|University of Western Sydney, Liverpool, New South Wales, Australia.
authors: Ivan Ho
authors: IH
authors: Shon
authors: University of New South Wales, Liverpool, New South Wales, Australia.|Department of Nuclear Medicine and PET, Liverpool Hospital, Liverpool, New South Wales, Australia.|University of Western Sydney, Liverpool, New South Wales, Australia.
authors: Michael
authors: M
authors: Lin
authors: Cancer Therapy Centre, Liverpool Hospital, Liverpool, New South Wales, Australia.|University of New South Wales, Liverpool, New South Wales, Australia.|Ingham Institute of Applied Medical Research, Liverpool, New South Wales, Australia.
authors: Dion
authors: D
authors: Forstner
authors: Department of Radiation Oncology, Calvary Mater Newcastle, Waratah, New South Wales, Australia.|University of Newcastle, Callaghan, New South Wales, Australia.
authors: Minh Thi
authors: MT
authors: Tieu
authors: Department of Nuclear Medicine and PET, Liverpool Hospital, Liverpool, New South Wales, Australia.
authors: Andrew
authors: A
authors: Chicco
authors: Cancer Therapy Centre, Liverpool Hospital, Liverpool, New South Wales, Australia.
authors: Victoria
authors: V
authors: Bray
authors: Cancer Therapy Centre, Liverpool Hospital, Liverpool, New South Wales, Australia.
authors: Allan
authors: A
authors: Fowler
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D019788:Fluorodeoxyglucose F18; D006801:Humans; D053208:Kaplan-Meier Estimate; D008875:Middle Aged; D000072078:Positron Emission Tomography Computed Tomography
chemical_list: D019788:Fluorodeoxyglucose F18
keywords: FDG PET; adaptive radiotherapy; head and neck cancer; metabolic parameters; predictive value