title: Early FDG-PET imaging after radical radiotherapy for non-small-cell lung cancer: inflammatory changes in normal tissues correlate with tumor response and do not confound therapeutic response evaluation.
abstract: OBJECTIVE
  To investigate the relationship between positron emission tomography (PET) detected inflammatory changes in irradiated normal tissues and metabolic response at tumor sites in patients receiving radical radiotherapy for non-small-cell lung cancer. The prognostic significance of these changes was also studied.
  
  
  METHODS
  In 73 consecutive patients, (18)F-fluorodeoxyglucose (FDG) PET was performed at a median of 70 days after completion of radical radiotherapy. Radiation-induced inflammatory change was scored for normal tissues within the radiation treatment volume using a 0-3 grading scale. Metabolic tumor response was assessed using a pattern-recognition algorithm comparing pre- and posttreatment scans. Prognostic significance of inflammatory changes was tested using the Cox proportional hazards regression model.
  
  
  RESULTS
  Increased FDG uptake in normal tissues (radiotoxicity) was associated with a greater likelihood of complete or partial tumor response on both PET (p = 0.0044) and computed tomography (p = 0.029). Prognostic stratification provided by PET response was both significant and of a similar magnitude in patients with low- and high-grade radiotoxicity.
  
  
  CONCLUSIONS
  Postradiotherapy inflammatory changes detected by FDG-PET are positively correlated with tumor response, suggesting that tumor radioresponsiveness and normal tissue radiosensitivity may be linked. Prognostic stratification provided by PET is not compromised by inflammatory changes if a meticulous visual response assessment technique is used.
authors.affiliation: Centre for Molecular Imaging, The Peter MacCallum Cancer Centre, Melbourne, Australia.
authors.forename: Rodney J
authors.initials: RJ
authors.lastname: Hicks
authors.forename: Michael P
authors.initials: MP
authors.lastname: Mac Manus
authors.forename: Jane P
authors.initials: JP
authors.lastname: Matthews
authors.forename: Annette
authors.initials: A
authors.lastname: Hogg
authors.forename: David
authors.initials: D
authors.lastname: Binns
authors.forename: Danny
authors.initials: D
authors.lastname: Rischin
authors.forename: David L
authors.initials: DL
authors.lastname: Ball
authors.forename: Lester J
authors.initials: LJ
authors.lastname: Peters
mesh_terms: D000230:Adenocarcinoma / Q000000981:diagnostic imaging / Q000532:radiotherapy; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging / Q000401:mortality / Q000532:radiotherapy*; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging / Q000532:radiotherapy; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging* / Q000378:metabolism; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000401:mortality / Q000532:radiotherapy*; D011379:Prognosis; D011446:Prospective Studies; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D014055:Tomography, Emission-Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18