Prognostic value of computed tomography-based sarcopenia for overall and disease-free survival in rectal cancer: an updated systematic review and meta-analysis

INTRODUCTION: Computed tomography (CT)-based sarcopenia has been proposed as a prognostic marker in rectal cancer (RC), but methodological heterogeneity limits comparability across studies. We conducted a systematic review and meta-analysis to assess the association of CT-based sarcopenia with overall survival (OS) and disease-free survival (DFS) in patients with RC, and to explore potential methodological sources of heterogeneity. METHODS: PubMed, Web of Science, Scopus and EMBASE were searched through August 2025. Observational studies reporting hazard ratios (HRs) for OS and/or DFS according to preoperative CT-based sarcopenia were selected. Crude and adjusted HRs were analyzed separately using three-level random-effects meta-analytic models to account for within-study multiplicity. Meta-regression, subgroup, and sensitivity analyses were performed to explore heterogeneity. Risk of bias and certainty of evidence were assessed using the Quality in Prognosis Studies and the Grading of Recommendations Assessment, Development and Evaluation approaches, respectively. RESULTS: Twenty-five studies comprising 7569 patients were included. CT-based sarcopenia was associated with worse OS in both crude (pooled HR 2.02; 95% CI 1.64-2.50) and adjusted analyses (pooled HR 2.21; 95% CI 1.74-2.81), and with worse DFS in both crude (pooled HR 1.34; 95% CI 1.10-1.62) and adjusted analyses (pooled HR 1.74; 95% CI 1.41-2.14). Prediction intervals crossed the null for crude OS and crude DFS, but not for adjusted OS. Higher sarcopenia prevalence was associated with attenuated adjusted OS effects, whereas lower SMI cut-offs were associated with larger crude OS effects. No consistent effect modification was observed according to geographic region or timing of sarcopenia assessment. Certainty of evidence ranged from moderate for crude OS to low for adjusted OS and both DFS analyses. CONCLUSIONS: CT-based sarcopenia is associated with worse OS and DFS in patients with RC across crude and adjusted analyses, supporting its potential prognostic value in RC. However, greater standardization and prospective validation are needed before routine clinical implementation.