Cachexia may well represent the flip side of the tremendous achievements of modern medicine. Many diseases rapidly leading patients to death just a few years ago, are now better controlled by new therapies, and even if we cannot cure and eradicate them, their natural history has significantly increased by months and years. Although these new therapeutic strategies represent a remarkable advantage over the standards of care, it is impossible to ignore that many more patients are now facing the nutritional consequences of prolonged immunological and metabolic challenges deriving from ongoing diseases and aggressive therapies. Aim of the volume, written by world-renowned scientists, is to provide the best available evidence on the pathogenesis, clinical features and therapeutic approach of cachexia, and to facilitate the understanding of the complex yet unequivocal clinical role of this syndrome, that truly represents a disease, or, better still, a disease within other different diseases.