LAUSR

BACKGROUND & AIMS Resting energy expenditure (REE) is variable in cancer and might be influenced by changes in tumor burden, systemic inflammation, and body composition. The objective of this study was to assess REE change and the predictors of such in patients with stage III or IV colorectal cancer. METHODS REE was measured via indirect calorimetry and fat mass and fat-free mass (FFM) were assessed using dual X-ray absorptiometry as part of a unique analysis of two studies. C-reactive protein (CRP) was measured as an inflammatory marker. Linear regression was used to assess the determinants of REE at baseline and REE change, with days between baseline and follow-up measures included as a covariate. RESULTS One-hundred and nine patients were included at baseline (59.6% male; 67 ± 12 years; body mass index 24.1 ± 4.3 kg/m2); 49 had follow-up data (61.2% male; 65 ± 12 years; body mass index 25.4 ± 4.3 kg/m2), with median follow-up of 119 days (interquartile range: 113-127 days). At baseline, age, FFM, and CRP explained 68.9% of the variability in REE. A wide variability in REE change over time was observed, ranging from -156 to 370 kcal/day, or -13.0 to 15.7%/100 days. CRP change (1.7 ± 0.4 mg/L, p < 0.001) and stage (81.3 ± 38.7, p = 0.042) predicted REE change in multivariate analysis, controlling for age, FFM change, and days between visits (R2: 0.417 ± 88.2, p < 0.001). CONCLUSIONS Age, FFM, and CRP predicted REE at a single time point. REE change was highly variable and explained by inflammation and stage. Future research should investigate the validity and feasibility of incorporating these measures into energy needs recommendations.