Association Between Low Relative Muscle Mass and the Risk of Colorectal Neoplasms

Goals: We aimed to ascertain whether low relative muscle mass is associated with colorectal neoplasm (CRN) risk. Background: CRN and sarcopenia have common pathophysiological mechanisms such as insulin resistance, chronic inflammation, and physical inactivity. However, the direct relationship between the 2 diseases has not been investigated. Study: A cross-sectional study was performed on 81,885 examinees who underwent colonoscopy as part of a health check-up. The skeletal muscle mass index (SMI) [SMI (%)=total skeletal muscle mass (kg)/body weight (kg)×100] was estimated using a bioelectrical impedance analyzer. Results: Of 81,885 participants, 52,272 were men and 29,613 were women. The prevalence rate of CRN in subjects in quartiles 1, 2, 3, and 4 of SMI was 22.8%, 20.5%, 18.2%, and 14.9% among men, and 14.8%, 11.8%, 9.7%, and 8.2% among women, respectively (Ptrend<0.001). In a multivariable-adjusted model, the inverse associations between SMI and prevalence of CRN remained significant. In men, the adjusted odds ratios (95% confidence interval) for overall CRN comparing each of the quartiles 1, 2, and 3 of SMI with the quartile 4 were 1.41 (1.32 to 1.52), 1.24 (1.16 to 1.33), and 1.12 (1.04 to 1.20), and those for advanced CRN were 1.64 (1.34 to 2.01), 1.38 (1.12 to 1.70), and 1.12 (0.90 to 1.40), respectively (all Ptrend<0.001). In women, those for overall CRN were 1.18 (1.04 to 1.33), 1.15 (1.01 to 1.30), and 1.05 (0.93 to 1.20), respectively (Ptrend=0.006). Conclusions: Relative muscle mass was negatively associated with CRN prevalence, supporting low muscle mass as an independent risk factor for CRN. Our results may provide a novel insight into the mechanisms linking low muscle mass and CRN.