BACKGROUND: Muscle loss, characterized by reduced muscle mass (myopenia), and infltration by intermuscular and intramuscular fat (myosteatosis), predicts a poor short-term prognosis in patients with colorectal cancer. However, little is known about the in?uence of myopenia and myosteatosis on long-term outcomes. OBJECTIVE: The present study aimed to evaluate the prognostic in?uence of both myopenia and myosteatosis on long-term outcomes after curative colorectal cancer surgery. DESIGN: This is a retrospective analysis using a propensity score-matched analysis to reduce the possibility of selection bias. SETTINGS: The study was conducted at a single institution. PATIENTS: We performed a retrospective analysis of 211 consecutive patients with stage I to III colorectal cancer who underwent curative surgery between 2010 and 2011. INTERVENTION: CT scans were analyzed to calculate the lumbar skeletal muscle index and mean muscle attenuation using a SYNAPS VINCENT. MAIN OUTCOME MEASURES: The primary outcome measure was cancer-specifc survival. Secondary end points included overall survival and disease-free survival. RESULTS: Of 211 patients, a total of 102 and 106 were matched for myopenia and myosteatosis analyses. The median follow-up was 57.6 months. Versus the nonmyopenia group, the myopenia group manifested a signifcantly shorter cancer-specifc survival, overall survival, and disease-free survival. Signifcantly shorter cancer-specifc survival and overall survival times were also identifed for the myosteatosis versus the nonmyosteatosis group. Before matching, multivariate analyses identifed both myopenia and myosteatosis as independent prognostic factors for cancer-specifc survival (p = 0.04 and p < 0.01), overall survival (p = 0.03 and p < 0.01), and disease-free survival (p < 0.01 and p < 0.01). LIMITATIONS: This study is limited by its retrospective, nonrandomized design. CONCLUSIONS: Myopenia and myosteatosis adversely affect long-term outcomes after curative colorectal cancer resection.
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