Effect of changes in body composition and sociodemographic factors on colon cancer survival.

296 Background: Muscle mass, muscle quality, and adipose tissue volumes have been shown to affect colon cancer survival. Further research is required to understand how change in body composition during treatment impacts colon cancer outcomes, and how covariables such mental health and socioeconomic status affect this relationship. The aim of this project was to examine how changes in body composition during chemotherapy for colon cancer impact the duration of disease-free survival (DFS) and how sociodemographic covariables (age, sex, social isolation, depression, anxiety, income, community size) influence this relationship. Methods: Computed tomography (CT) scans from the time of diagnosis and the end of chemotherapy were obtained from individuals treated for stage III colon cancer with oxaliplatin at BC Cancer between 2012 and 2016. Whole body tissue volumes were estimated based on CT images at the level of the third lumbar vertebra, analysed using DAFS Express (Voronoi Health Analytics Inc., Vancouver BC). Muscle quantity was measured as skeletal muscle index (SMI), and muscle quality was measured as skeletal muscle density (SMD) and skeletal muscle gauge (SMG). Quantity of visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), intermuscular adipose tissue (IMAT), and total adipose tissue (TAT) were also measured. Social isolation, anxiety, and depression symptoms were measured using the validated Psychosocial Screen for Cancer–Revised. Neighbourhood income and community population were estimated using postal codes. Cox proportional hazard models were calculated for the effect of body composition variables on DFS, and interactions with sociodemographic variables. Results: Significant reductions in SMI, SMD, SMG, VAT, IMAT and TAT were observed between diagnosis and post-chemotherapy (n=282). Improved survival was associated with higher SMD and lower IMAT at diagnosis and post-chemotherapy, lower VAT at diagnosis, and an increase in VAT or TAT during chemotherapy. Body composition had a more significant effect on survival in individuals who were older, female, or lived in smaller communities. Conclusions: Significant reductions in SMI, SMD, SMG, VAT, IMAT and TAT were observed between diagnosis and post-chemotherapy (n=282). Improved survival was associated with higher SMD and lower IMAT at diagnosis and post-chemotherapy, lower VAT at diagnosis, and an increase in VAT or TAT during chemotherapy. Body composition had a more significant effect on survival in individuals who were older, female, or lived in smaller communities.