[Sarcopenia in gastrointestinal oncology: Diagnostic criteria, clinical implications and management].

Sarcopenia is defined as a loss of muscle mass and strength. It represents a frequent and multifactorial complication in patients with gastrointestinal cancers, resulting from the combined effects of malnutrition, chronic inflammation, metabolic alterations, and reduced physical activity level. Its assessment relies on a combined approach integrating imaging tools and functional tests. Computed tomography, widely available in oncology, represents the reference method for the evaluation of body composition, particularly skeletal muscle mass and quality. Functional tests allow assessment of muscle strength and physical performance. Sarcopenia, including sarcopenic obesity phenotype, has a major prognostic impact from localized disease to advanced stages, being associated with an increased risk of postoperative complications, reduced tolerance to anticancer treatments, and decreased survival. Its management should be early, personalized, and multimodal, combining nutritional support, adapted physical activity, and a global patient-centered approach. Prehabilitation programs illustrate the benefits of an integrated strategy, whereas pharmacological approaches remain limited to date. Thus, sarcopenia should be considered an essential component of the care pathway in gastrointestinal oncology.