Morphologic change of the psoas muscle as a surrogate marker of sarcopenia and predictor of complications after colorectal cancer surgery

Sarcopenia is reported to be associated with complications after surgery. However, there is no established optimal parameter to determine sarcopenia affecting surgical outcome. This study investigated whether morphologic change of the psoas muscle (MPM) reflects sarcopenia and could be a predictor of complications after colorectal cancer surgery. Colorectal cancer patients who underwent primary tumor resection with anastomosis between 2015 and 2016 were analyzed. MPM score was evaluated as the ratio of the short-to-long axis of the psoas muscle in CT images at the L3 vertebrae and classified into five MPM grades. Then, the impact of MPM grade on development of postoperative complications was investigated. A total of 133 patients were studied. MPM score was significantly correlated to the sectional areas of the psoas muscle at the L3 vertebrae which was evaluated by manual tracing. 21.1% of the subjects were classified into severe MPM (defined as MPM grade 3–4). Overall and infectious complications were noted in 37 (27.8%) and 16 (12.0%) patients. Severe MPM (odds ratio [OR] 2.71, 95% confidence interval [CI] 1.09–6.73), longer operative time (OR 1.01, 95%CI 1.001–1.01), and open surgery (OR 2.73, 95%CI 1.17–6.35) were identified as independent risk factors of overall complications. Severe MPM (OR 4.26,95%CI 1.38–13.10) and open surgery (OR 3.42, 95%CI 1.11–10.48) were identified as independent factors associated with infectious complications. MPM grade may be used as a simple and convenient marker of sarcopenia and to identify patients at increased risk of complications after colorectal cancer surgery.