title: Metabolic tumor burden predicts for disease progression and death in lung cancer.
abstract: OBJECTIVE
  In lung cancer, stage is an important prognostic factor for disease progression and survival. However, stage may be simply a surrogate for underlying tumor burden. Our purpose was to assess the prognostic value of tumor burden measured by 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging.
  
  
  METHODS
  We identified 19 patients with lung cancer who had staging PET-CT scans before any therapy, and adequate follow-up (complete to time of progression for 18, and death for 15 of 19). Metabolically active tumor regions were segmented on pretreatment PET scans semi-automatically using custom software. We determined the relationship between times to progression (TTP) and death (OS) and two PET parameters: total metabolic tumor volume (MTV), and standardized uptake value (SUV).
  
  
  RESULTS
  The estimated median TTP and OS for the cohort were 9.3 months and 14.8 months. On multivariate Cox proportional hazards regression analysis, an increase in MTV of 25 ml (difference between the 75th and 25th percentiles) was associated with increased hazard of progression and of death (5.4-fold and 7.6-fold), statistically significant (p = 0.0014 and p = 0.001) after controlling for stage, treatment intent (definitive or palliative), age, Karnofsky performance status, and weight loss. We did not find a significant relationship between SUV and TTP or OS.
  
  
  CONCLUSIONS
  In this study, high tumor burden assessed by PET MTV is an independent poor prognostic feature in lung cancer, promising for stratifying patients in randomized trials and ultimately for selecting risk-adapted therapies. These results will need to be validated in larger cohorts with longer follow-up, and evaluated prospectively.
authors.affiliation: Department of Radiation Oncology, Stanford University, Stanford, CA 94305-5847, USA.
authors.forename: Percy
authors.initials: P
authors.lastname: Lee
authors.forename: Dilani K
authors.initials: DK
authors.lastname: Weerasuriya
authors.forename: Philip W
authors.initials: PW
authors.lastname: Lavori
authors.forename: Andrew
authors.initials: A
authors.lastname: Quon
authors.forename: Wendy
authors.initials: W
authors.lastname: Hara
authors.forename: Peter G
authors.initials: PG
authors.lastname: Maxim
authors.forename: Quynh-Thu
authors.initials: QT
authors.lastname: Le
authors.forename: Heather A
authors.initials: HA
authors.lastname: Wakelee
authors.forename: Jessica S
authors.initials: JS
authors.lastname: Donington
authors.forename: Edward E
authors.initials: EE
authors.lastname: Graves
authors.forename: Billy W
authors.initials: BW
authors.lastname: Loo
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D018450:Disease Progression; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000401:mortality* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D010865:Pilot Projects; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D012044:Regression Analysis; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18