Measurement of body mass by bioelectrical impedance analysis and computed tomography in cancer patients with malnutrition - a cross-sectional observational study.

Malnutrition and cachexia affects the majority of cancer patients and significantly worsens their quality of life and prognosis. However, the diagnostic criteria of malnutrition and cachexia remain a topic under constant debate. To overcome this hurdle, diagnostic tools to objectively detect and quantify the loss of muscle and fat mass are needed. Computed tomography (CT)-based measurement is currently considered the golden standard. Bioelectrical impedance analysis (BIA) is an economical, non-invasive tool but it is seen controversial in patients with cancer and malnutrition because of possible estimation errors.BIA and CT-based analysis of body mass compartments were performed 172 times in 118 cancer patients, within the nutrition program of our institution. Prevalence of malnutrition was determined according to the global leadership initiative on malnutrition criteria. Data obtained for muscle and fat mass from both BIA and CT were correlated using Pearson's ρ. All analyses were performed with an explorative significance level of 5%.45.7% of the cohort were classified as "malnourished." No significant differences were observed between the 2 groups regarding demographic data. Median body mass index, Karnofsky performance status, and nutritional risk score were lower in the malnourished group. Values for muscle and fat mass by BIA and CT were significantly lower in malnourished patients. Correlation of the measured parameters were highly significant between CT-based and BIA measurement. In the overall cohort, correlation of measured muscle mass values by CT and BIA was significant with Pearson's ρ = 0.794 (P < .01). Looking at patients without malnutrition only, Pearson's ρ was 0.754 (P < .01). The correlation of measured fat mass values was equally significant, with Pearson's ρ of 0.748 (P < .01) in the overall cohort and 0.771 (P < .01) in patients with malnutrition.To our knowledge, this is the first study comparing BIA to CT-based body mass analysis in a large cohort of cancer patients with malnutrition. The results suggest that BIA is a valid diagnostic tool for the assessment of muscle and fat mass, even in patients with malnutrition, and could be implemented for the early detection and short-term follow-up of malnutrition and cachexia.

Motor protein function in skeletal abdominal muscle of cachectic cancer patients.

Cachexia presents with ongoing muscle wasting, altering quality of life in cancer patients. Cachexia is a limiting prognostic factor for patient survival and health care costs. Although animal models and human trials have shown mechanisms of motorprotein proteolysis, not much is known about intrinsic changes of muscle functionality in cancer patients suffering from muscle cachexia, and deeper insights into cachexia pathology in humans are needed. To address this question, rectus abdominis muscle samples were collected from several surgical control, non-cachectic and cachectic cancer patients and processed for skinned fibre biomechanics, molecular in vitro motility assays, myosin isoform protein compositions and quantitative ubiquitin polymer protein analysis. In pre-cachectic and cachectic cancer patient samples, maximum force was significantly compromised compared with controls, but showed an unexpected increase in myofibrillar Ca(2+) sensitivity consistent with a shift from slow to fast myosin isoform expression seen in SDS-PAGE analysis and in vitro motility assays. Force deficit was specific for 'cancer', but not linked to presence of cachexia. Interestingly, quantitative ubiquitin immunoassays revealed no major changes in static ubiquitin polymer protein profiles, whether cachexia was present or not and were shown to mirror profiles in control patients. Our study on muscle function in cachectic patients shows that abdominal wall skeletal muscle in cancer cachexia shows signs of weakness that can be partially attributed to intrinsic changes to contractile motorprotein function. On protein levels, static ubiquitin polymeric distributions were unaltered, pointing towards evenly up-regulated ubiquitin protein turnover with respect to ubiquitin conjugation, proteasome degradation and de-ubiquitination.