UBC Theses and Dissertations
The influence of social and psychological factors on the relationship between body composition and colon cancer outcomes Schulte, Hannah Kathleen
The current five-year survival rate for colorectal cancer in Canada is 65%, which is influenced by well-established factors (e.g., age, cancer stage). There is also consistent observational research that higher body mass or social factors (e.g., living alone) can negatively impact survival. This thesis project examined the association between body composition at diagnosis and relapse-free survival (RFS) at three years post-diagnosis, and how these relationships may be influenced by social or psychological factors at diagnosis in individuals with colon cancer. Methods: A cohort of individuals treated for stage III colon cancer at BC Cancer from 2012 to 2015 with clinical and demographic data available was created. CT scans of the third lumbar vertebra at diagnosis were analyzed to determine skeletal muscle index (SMI) (muscle cross-sectional area normalized for height), sarcopenia (using published SMI cut-off points), skeletal muscle density (SMD) (average attenuation of muscle), and skeletal muscle gauge (SMG) (SMI multiplied by SMD). Social and psychological factors were obtained at diagnosis and included social isolation, patient-reported concerns, and symptoms of anxiety and depression from BC Cancer’s Psychosocial Screen for Cancer-Revised, and community size and neighbourhood income based on individuals’ postal codes. Multivariable logistic regression models were used to examine: 1) The associations of SMI, SMD, SMG, and sarcopenia with RFS; 2) How social and psychological factors (selected using variable visualization and univariable regression) influenced the relationships. Results: Individuals were a median age of 62.0 years and 51.1% were male. Individuals with a lower SMD (OR= 0.97, 95% CI= 0.95,0.997), lower SMG (for a 100-unit change, OR= 0.93, 95% CI= 0.88,0.98), or sarcopenia (OR= 1.80, 95% CI= 1.06,3.10) had greater odds of having a relapse. This association was influenced by social isolation; for any given SMD, SMG, or sarcopenia status, individuals with one or more markers of social isolation had approximately two times greater odds of having a relapse than individuals without markers of social isolation. Conclusion: Consistent with the literature, sarcopenia was associated with RFS, as was SMD and SMG, measures for which there is less evidence surrounding their relationship with long-term outcomes. Social isolation appeared to influence these relationships.
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