Abstract
BACKGROUND: Skeletal muscle depletion is a prognostic factor in patients with cancer. Here, we evaluated the association between the skeletal muscle index (SMI) and local and systemic responses in patients with colon cancer. PATIENTS AND METHODS: We analyzed the relationships of the SMI with neutrophil, lymphocyte, monocyte, and platelet counts; the neutrophil-to-lymphocyte ratio; albumin levels; and C-reactive protein levels in a cohort of 561 patients, and with the circulating levels of 39 cytokines in a cohort of 125 patients. We also studied the association between the SMI and tumor local inflammatory response and the effect of SMI on survival. RESULTS: The median SMIs for male and female subjects were 44.1 and 34.2 cm(2)/m(2), respectively. We observed positive correlations of the SMI with neutrophil (p=0.022), lymphocyte (p=0.001), and monocyte counts (p=0.003). A low SMI correlated significantly with an increased platelet count (p=0.017), decreased albumin level (p=0.006), neutrophil-to-lymphocyte ratio >3 (p=0.021), and an increased interferon γ-induced protein 10 level (IP-10, r = -0.276, p=0.002). The SMI did not correlate significantly with local inflammatory reactions or the C-reactive protein level. Finally, the SMI was a significant prognosticator in patients with stage III colon cancer (3-year disease-free survival rates: 35.1% for the low SMI arms versus 46.0% in the high SMI arms; HR =2.036; p=0.034). CONCLUSION: This study highlights the association of a low SMI with a high systematic inflammatory response and IP-10 levels. Furthermore, low SMI is a predictor of poor disease-free survival in patients with stage III colon cancer.