Friday, April 5, 2013
In a paper just published in the Journal of Clinical Oncology, Lisa Martin and colleagues from the University of Alberta studied around 1,500 patients with various stages of lung or gastrointestinal cancer presenting with a wide range of BMI (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 (measured by CT).
Irrespective of BMI, high weight loss, low muscle index, and low muscle attenuation were independently prognostic of survival.
Compared to a survival model containing conventional covariates (cancer diagnosis, stage, age, performance status), a model ignoring these variables but including only BMI, weight loss, muscle index, and muscle attenuation proved a far better predictor of patient survival.
Patients who had higher weight loss and lower muscle indicators survived 8.4 months, 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.
From these finding the authors conclude that, regardless of BMI, cancer patients presenting with involuntary weight loss, muscle depletion and muscle attenuation share the poorest prognosis.
Thus, the authors note that,
“Our findings provide evidence in support of the proposed international consensus definition of cancer cachexia as a multifactorial syndrome defined by an ongoing loss of skeletal muscle mass with or without loss of fat mass.”
Once again, simply stepping on a scale appears to be a rather limited measure of health.
Martin L, Birdsell L, Macdonald N, Reiman T, Clandinin MT, McCargar LJ, Murphy R, Ghosh S, Sawyer MB, & Baracos VE (2013). Cancer Cachexia in the Age of Obesity: Skeletal Muscle Depletion Is a Powerful Prognostic Factor, Independent of Body Mass Index. Journal of clinical oncology : official journal of the American Society of Clinical Oncology PMID: 23530101