Measurements of resting energy expenditure and body composition before and after treatment of small cell lung cancer

Abstract
Many patients with small cell lung cancer are reported to lose weight, but the mechanism of this effect is unclear. Measurements of resting energy expenditure (REE), using indirect calorimetry and body composition (fat, fat-free mass and organ mass), using dual energy X-ray absorptiometry (DXA) and abdominal CT scans were measured in 38 patients with newly-diagnosed small cell lung cancer. Twenty-eight patients were restudied at the end of treatment. In those who responded to treatment there was no change in body weight, but a decrease in REE of 15.7 ±11.7 kJ/kg fat free mass/day, whilst in the non-re-sponders body weight decreased by 4.33 ± 5.4 kg, but REE was unchanged. This study provides evidence for tumour-induced hypermetabolism which is independent of changes in gross body composition, although the absolute increase is small, approximately 0.8 MJ/day. However since body weight was maintained in those patients who responded to treatment either total energy expenditure was decreased, implying decreases in physical activity, or energy intake was increased.