Prognostic value of sarcopenia in patients with rectal cancer: A meta-analysis

BACKGROUND: Sarcopenia is usually characterized by the loss of skeletal muscle mass and impaired muscle function which is commonly seen in the elderly. It has been found to be associated with poorer prognoses in many types of cancer. Computed tomography (CT) scan is frequently used to assess skeletal muscle mass and further calculate skeletal muscle index (SMI) at the third lumbar vertebra level (L3), which is used to define sarcopenia. The purpose of this meta-analysis was to assess the prognostic value of sarcopenia for overall survival (OS) in patients with rectal cancer. METHODS: We performed a systematic search to find relevant studies published up to 14 January 2021 in PubMed, Embase, Web of science and Scopus. In our meta-analysis, studies comparing OS in rectal cancer patients with sarcopenia versus those without were included. Quality assessment for included studies was evaluated according to the Quality in Prognosis Studies (QUIPS) tool. We directly extracted hazard ratios (HRs) with 95% confidence intervals (CIs) in both univariate and multivariate analyses from each study. The Cochrane Collaboration's Review Manager 5.4 software was applied to analyze data. The quality of evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) guidelines and website GRADEpro. RESULTS: Finally, a total of 7 studies involving 2377 patients were included. The pooled HRs were 2.10 (95% CI 1.33-3.32, P = 0.001) and 2.37 (95% CI 1.13-4.98, P = 0.02) using random-effects models in univariate and multivariate analyses, respectively. The results showed a significant association between sarcopenia and OS in patients with rectal cancer. The quality of the evidence for OS was moderate for both univariate and multivariate analyses. CONCLUSION: CT-defined sarcopenia is an independent predictor for worse OS in patients with rectal cancer. Future studies with a more stringent definition of sarcopenia are required to further confirm our findings.