Cancer patients with high weight loss, low muscle index, and low muscle attenuation have a poor prognosis regardless of body mass index (BMI), according to a study published online ahead of print in the Journal of Clinical Oncology.
To examine whether muscle depletion predicts survival in cancer, Lisa Martin, from the University of Alberta in Edmonton, Canada, and colleagues used computed tomography to assess 1,473 patients with lung or gastrointestinal cancer for weight loss history, lumbar skeletal muscle index, and mean muscle attenuation at presentation.
The researchers identified a wide variation in weight loss, muscle index, and muscle attenuation across all categories of BMI. Poorer survival was independently predicted by high weight loss, low muscle index, and low muscle attenuation. A model ignoring conventional variables and including BMI, weight loss, muscle index, and muscle attenuation gave a c statistic of 0.92, compared with a survival model including conventional covariates (cancer diagnosis, stage, age, and performance status), which gave a c statistic of 0.73. Regardless of BMI, patients with all three of these poor prognostic variables survived 8.4 months, whereas those with none of these features survived 28.4 months.
“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,” the authors write.