Pretherapeutic radiological sarcopenia in pancreatic ductal adenocarcinoma: a narrative review.

Pancreatic ductal adenocarcinoma (PDAC) remains one of the deadliest solid malignancies despite advances in surgery, perioperative care, and systemic therapies. Pretherapeutic radiological sarcopenia has emerged as a clinically relevant body-composition phenotype associated with poor outcomes in oncology. This imaging-based concept differs from contemporary geriatric definitions of sarcopenia, which require impaired muscle strength and incorporate low muscle quantity and/or quality. This narrative review critically examines radiological assessment, biological context, prognostic implications, artificial intelligence (AI)-enabled quantification, and interventional evidence in PDAC. A structured narrative search of PubMed/MEDLINE, Embase, and Google Scholar was conducted from database inception through July 31, 2026. Computed tomography (CT)-based skeletal muscle index remains the most widely validated imaging biomarker, although substantial heterogeneity persists in methods and diagnostic thresholds. Low muscle mass is most consistently associated with reduced survival, whereas associations with postoperative morbidity and systemic treatment toxicity are more heterogeneous. Exercise, nutritional, and multimodal cachexia interventions appear feasible and may provide functional or nutritional benefits, but evidence remains insufficient to establish a survival benefit from improving muscle status. AI-based approaches enable scalable body-composition analysis, although external validation, methodological standardization, and prospective clinical integration remain necessary. Overall, radiological sarcopenia is a promising prognostic and potentially actionable phenotype in PDAC.