title: Cancer cachexia in the age of obesity: skeletal muscle depletion is a powerful prognostic factor, independent of body mass index.
abstract: OBJECTIVE
  Emerging evidence suggests muscle depletion predicts survival of patients with cancer.
  
  
  METHODS
  At a cancer center in Alberta, Canada, consecutive patients with cancer (lung or GI; N = 1,473) were assessed at presentation for weight loss history, lumbar skeletal muscle index, and mean muscle attenuation (Hounsfield units) by computed tomography (CT). Univariate and multivariate analyses were conducted. Concordance (c) statistics were used to test predictive accuracy of survival models.
  
  
  RESULTS
  Body mass index (BMI) distribution was 17% obese, 35% overweight, 36% normal weight, and 12% underweight. Patients in all BMI categories varied widely in weight loss, muscle index, and muscle attenuation. Thresholds defining associations between these three variables and survival were determined using optimal stratification. High weight loss, low muscle index, and low muscle attenuation were independently prognostic of survival. A survival model containing conventional covariates (cancer diagnosis, stage, age, performance status) gave a c statistic of 0.73 (95% CI, 0.67 to 0.79), whereas a model ignoring conventional variables and including only BMI, weight loss, muscle index, and muscle attenuation gave a c statistic of 0.92 (95% CI, 0.88 to 0.95; P < .001). Patients who possessed all three of these poor prognostic variables survived 8.4 months (95% CI, 6.5 to 10.3), regardless of whether they presented as obese, overweight, normal weight, or underweight, in contrast to patients who had none of these features, who survived 28.4 months (95% CI, 24.2 to 32.6; P < .001).
  
  
  CONCLUSIONS
  CT images reveal otherwise occult muscle depletion. Patients with cancer who are cachexic by the conventional criterion (involuntary weight loss) and by two additional criteria (muscle depletion and low muscle attenuation) share a poor prognosis, regardless of overall body weight.
authors.affiliation: University of Alberta, Edmonton, Alberta, Canada. vickie.baracos@ualberta.ca
authors.forename: Lisa
authors.initials: L
authors.lastname: Martin
authors.forename: Laura
authors.initials: L
authors.lastname: Birdsell
authors.forename: Neil
authors.initials: N
authors.lastname: Macdonald
authors.forename: Tony
authors.initials: T
authors.lastname: Reiman
authors.forename: M Thomas
authors.initials: MT
authors.lastname: Clandinin
authors.forename: Linda J
authors.initials: LJ
authors.lastname: McCargar
authors.forename: Rachel
authors.initials: R
authors.lastname: Murphy
authors.forename: Sunita
authors.initials: S
authors.lastname: Ghosh
authors.forename: Michael B
authors.initials: MB
authors.lastname: Sawyer
authors.forename: Vickie E
authors.initials: VE
authors.lastname: Baracos
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D001823:Body Composition; D015992:Body Mass Index; D002100:Cachexia / Q000175:diagnosis / Q000209:etiology* / Q000401:mortality; D002170:Canada / Q000453:epidemiology; D002173:Cancer Care Facilities; D005260:Female; D005500:Follow-Up Studies; D005770:Gastrointestinal Neoplasms / Q000150:complications* / Q000401:mortality / Q000628:therapy; D006801:Humans; D008175:Lung Neoplasms / Q000150:complications* / Q000401:mortality / Q000628:therapy; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000473:pathology*; D009367:Neoplasm Staging; D009765:Obesity / Q000453:epidemiology*; D011379:Prognosis; D012307:Risk Factors; D015996:Survival Rate