The Impact Of Muscle And Adipose Tissue On Colon Cancer Survival

Low muscle mass at diagnosis is associated with decreased survival of colon cancer, but there is increasing interest in how muscle density and adipose tissue volumes affect cancer outcomes. Muscle density is a measure of muscle quality that describes the lipid infiltration in the muscle, with increased density correlating to increased muscle strength. PURPOSE: The project aims to determine the effect of muscle mass, muscle density and adipose tissue volume on stage III colon cancer recurrence-free survival. METHODS: Computed tomography (CT) scans from the time of diagnosis were used from individuals treated for stage III colon cancer at BC Cancer from 2012 to 2016. CT images at the level of the third lumbar vertebrae were used to estimate whole-body values using the automated image analysis software Slice-O-Matic (Tomovision, Magog, QC). CT-based body composition allows more in-depth analysis than the common measure of body mass index (BMI), which is height-adjusted weight. Muscle quantity is measured as skeletal muscle index (SMI), and quality is measured as skeletal muscle density (SMD). Visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) volumes were also measured. SMI is the cross-sectional muscle area divided by squared height, and SMD is the average attenuation of the muscle in Hounsfield units (HU). The cohort was stratified based on disease-free survival at 3 years (yes or no), and independent t-tests were performed for each body composition variable. RESULTS: The study included 350 individuals. The mean BMI was 27.1 kg/m2, SMI was 47.2 cm2/m2, SMD was 38.2 HU, VAT was 156.0 cm2 and SAT was 210.9 cm2. Individuals who experienced a recurrence or death within 3 years of diagnosis had significantly higher VAT (175.5 vs 148.1cm2, p = .047) and SAT (232.0 vs 202.3cm2, p = .045), and significantly lower SMD (36.2 vs 39.0 HU, p = .011). No significant differences were found for BMI (26.9 vs. 27.7 kg/m2, p = .25) or SMI (47.4 vs. 47.2, p = .89). CONCLUSION: Adipose tissue volumes and measures of muscle quality can both be used as prognostic factors in stage III colon cancer. Higher VAT and SAT volumes and lower muscle density predict shorter disease-free survival. These findings could inform the development of supportive care interventions to increase colon cancer survival. BC Cancer Foundation