Anorexia and Cachexia

Cachexia is a severe, multifactorial condition characterized by the significant loss of skeletal muscle mass and adipose tissue, commonly observed in patients with advanced cancer, chronic infections, and long-term illnesses such as chronic obstructive pulmonary disease (COPD), renal failure, heart failure, and late-stage, inflammatory autoimmune diseases. This condition is associated with increased proinflammatory factors and profound metabolic changes that differentiate it from simple starvation. In cachexia, fat stores are mobilized to replace glucose as the primary energy source, causing an altered metabolic state and an energy deficit. This metabolic dysregulation, combined with systemic inflammation, alimentary tract dysfunction, and anorexia, makes conventional nutritional support ineffective in reversing the condition. When significant anorexia accompanies cachexia, it is referred to as the anorexia-cachexia syndrome. Cachexia's frequency and severity vary among different cancers. Patients with gastrointestinal, pancreatic, and lung cancers experience cachexia more frequently, whereas those with breast cancer, sarcomas, and hematologic malignancies are less commonly affected. Cachexia, regardless of its underlying cause, diminishes overall well-being, impairs tolerance to medical and surgical treatments, and is linked to reduced survival rates. Diagnosing cachexia involves a multifactorial approach, incorporating clinical, biochemical, and functional assessments. Professional organizations have developed overlapping diagnostic criteria and management recommendations, but no universally accepted guidelines exist. The American Society of Clinical Oncology (ASCO) defines cancer cachexia as a multifactorial syndrome characterized by an ongoing loss of skeletal muscle mass not fully reversed by conventional nutritional support, leading to progressive functional impairment. The diagnostic criteria include weight loss of greater than 5% in 6 months or greater than 2% in individuals already exhibiting sarcopenia or a low body mass index (BMI) of less than 20 kg/m². In addition, the Society of Cachexia and Wasting Disorders has proposed diagnostic criteria for non–cancer-specific cachexia, including weight loss of 5% in 6 months with at least 3 of 5 clinical symptoms—fatigue, anorexia, decreased muscle strength, reduced fat-free mass, or systemic signs of inflammation. The Asian Working Group for Cachexia criteria include the presence of an underlying chronic disease, weight loss of greater than 5% in 6 months or a BMI of less than 20 kg/m² with ongoing weight loss of greater than 2%, and at least 1 of the following—anorexia with loss of appetite or reduced food intake, decreased muscle strength measured by grip strength, and elevated inflammatory markers such as a C-reactive protein level greater than 5 mg/L. The pathophysiology of cachexia involves a complex interplay of systemic inflammation and metabolic derangements. These factors contribute to weight loss, muscle atrophy, and diminished physical function, worsening patients' prognosis. Recognizing and managing cachexia early is crucial, as its progression significantly impairs quality of life and treatment outcomes. This educational activity reviews the etiology, diagnosis, and management of cachexia. The activity provides healthcare professionals with essential knowledge and strategies for evaluating patients with cachexia, assessing their nutritional status, identifying the underlying causes, and implementing effective interventions. By enhancing understanding of the pathophysiology and prognosis of cachexia, this course aims to improve patient care and clinical outcomes.