Racial differences in body composition and survival among older adults with gastrointestinal malignancies

Introduction: Muscle and adipose tissue measures can be quantified from routinely obtained computed tomography (CT) images and are predictors of chemotherapy-related toxicities and survival among patients with gastrointestinal (GI) malignancies. Most studies to date have consisted of predominantly White patients, and the role of body composition among minoritized racial groups is unknown. We examined racial differences in body composition and survival among patients with GI malignancies. Materials and Methods: This was a prospective cohort study of patients with GI malignancies. Single slices of axial CT images from L3 segments were analyzed using Slice-O-Matic software. The skeletal muscle area (cm 2 ) was divided by height to obtain the skeletal muscle index (SMI, cm 2 /m 2 ). Skeletal muscle radiodensity (SMD) in Hounsfield units (HU) was used for muscle composition. We compared body composition parameters between non-Hispanic (NH) -White and NH -Black participants. Cox models were used to examine the impact of body composition on survival. We proposed new race-specific cutoffs for body composition using optimal stratification. Results: Five hundred forty patients were included, of which 24% were NH -Black. In Cox models stratified by race, each 5 cm 2 /m 2 decrease in SMI was associated with increase in risk of all-cause mortality in NH -Black patients (hazard ratio [HR] 1.25; 95% confidence interval [CI] 1.04 -1.49 p = 0.02). With the existing cut points, neither sarcopenia nor myosteatosis was associated with worse survival. Using a new cutoff for sarcopenia in NH -Black patients, NH -Black patients with sarcopenia (HR 2.31 95%CI 1.10 -4.88 p = 0.03) and myosteatosis (HR 2.63 95% CI 1.25 -5.53 p = 0.01) had worse survival. Discussion: NH -Black older patients with GI cancers and sarcopenia or myosteatosis have worse overall survival.