The relationship between sarcopenia and breast cancer: mechanistic pathways and clinical relevance.

Breast cancer is the most frequently diagnosed malignancy among women worldwide and one of the leading causes of cancer-related mortality. Despite advances in screening and therapeutic strategies, its prevention and treatment continue to face considerable challenges due to pronounced tumor heterogeneity, therapeutic resistance, and treatment-related toxicities. Sarcopenia, a syndrome characterized by progressive loss of skeletal muscle mass (SMM) and function, is increasingly prevalent in patients with breast cancer and has been consistently associated with adverse clinical outcomes. In this review, we systematically summarize epidemiological evidence linking sarcopenia to breast cancer and elucidate its association with increased postoperative complications, heightened toxicity from systemic therapies, and inferior survival outcomes. We further explore potential pathophysiological mechanisms underlying this association, including altered pharmacokinetics that may contribute to exacerbated drug toxicity, dysregulated myokine signaling, and chronic inflammation that is linked to tumor progression, insulin resistance, and detrimental changes in physical function and health behaviors. In addition, current evidence regarding strategies for the identification and management of sarcopenia-encompassing diagnostic assessments, pharmacological interventions, nutritional support, and exercise training-is critically evaluated. By integrating current findings, this review highlights the pivotal role of sarcopenia in the development and progression of breast cancer and provides insight into multimodal intervention strategies that may improve clinical outcomes in this population.