Sarcopenia in colorectal cancer is related to socio-economic deprivation and Body Mass Index alone misrepresents underlying muscle loss in the deprived.

ABSTRACT

BACKGROUND & AIMS: Patients with colorectal cancer who are more socio-economically deprived have worse outcomes; deprivation is also associated with higher obesity rates, defined as a body mass index (BMI) of greater than thirty. Body composition (BC) factors such as sarcopenia and myosteatosis are also known to predispose to poorer outcomes following colorectal cancer surgery. There is limited evidence to date to relate the effect of deprivation upon these host characteristics that are linked to prognosis. We aimed to examine the relationship between deprivation and body composition in colorectal cancer. METHODS: Analysis was performed on a prospectively collected database of preoperative primary colorectal cancer patients at St Mark's - The National Bowel Hospital, UK. Body composition characteristics were identified by analysing the L3 axial slices of Computer Tomogram (CT) slices of preoperative staging using Slice-O-Matic software with Automatic Body composition Analyser using Computed tomography image Segmentation (ABACS) L3 plug-in. Deprivation status for each patient was determined using their postal code which was linked to the Index of Multiple Deprivation (IMD). Each domain of the IMD was examined individually in relation to BC characteristics. Binary logistic regression analysis was performed on the data using a model developed from previous published analyses of this dataset. RESULTS: Four hundred and nineteen patients were included in the final analysis, the median age was 69 years and 57% of the patient population was male. Patients who were more deprived were significantly more likely to be sarcopenic [OR 1.56 (95% CI 1.01-2.41, p = 0.045)] and myosteatotic [OR 1.69 (95% CI 1.019-2.81, p = 0.042)]. More deprived patients were also more likely to have a lower BMI [OR 0.60 (95% CI 0.38-0.94, p = 0.026)] despite no significant difference in visceral obesity between the most and least deprived. CONCLUSIONS: Deprivation is an important independent determinant of sarcopenia in the colorectal cancer population. Identifying these patients early and addressing reversible factors may help improve post-operative surgical outcomes in this poor prognostic group. Sarcopenia may be a premorbid state in the deprived colorectal cancer patient that may not be wholly driven by tumour characteristics.