Supplementary Material for: Exploring the Impact of Sarcopenia on Mortality in Breast Cancer Patients: A Comprehensive Systematic Review and Meta-Analysis

Background: This study assesses the frequency of sarcopenia in patients with breast cancer (BC) and its association with mortality rates. Methods: An all-encompassing search across (PubMed, Scopus, Web of Science, and CINAHL) was done, to identify studies, published until August 2023, that report data on sarcopenia and mortality in BC patients. A meta-analysis was then done using a random-effects model. Results: Out of 989 initially identified potential studies, 19 met inclusion criteria. Analysis of 15 studies showed a rate of sarcopenia of 38% (95% CI 29-48%), with moderate heterogeneity (I2 = 25.8%). Sarcopenia was linked to increased mortality risk in BC patients across 16 studies (HR: 1.77, CI: 1.35 – 2.32, p = <0.001) with both shorter and longer follow-up periods. Similarly, mortality risks were significantly higher in metastatic (HR: 1.52, CI: 1.14 – 2.03, p = 0.004) and non-metastatic (HR: 2.55, CI: 1.66 – 3.93, p < 0.001) BC patients with sarcopenia. Conclusion: Our analysis demonstrates a substantial prevalence of sarcopenia in BC patients. Importantly, sarcopenia was significantly linked to elevated risk of mortality in this population. Subgroup analyses, stratified by follow-up periods and disease stage, consistently reveal increased mortality risks associated with sarcopenia, underscoring its clinical relevance in both short- and long-term patient outcomes. Our findings further strengthen the need to recognize and address sarcopenia as a critical factor in BC management and prognosis.