[Causes and impact of hyponutrition and cachexia in the oncologic patient].

The maximal expression of hyponutrition in cancer is tumoral cachexia, which will direct or indirectly account for mortality in one third of cancer patients. Causes of hyponutrition in cancer are related with the tumor, the patient, or therapies, and summarily we may differentiate four main mechanisms by which hyponutrition may occur in cancer patients: Poor energy and nutrients intake; Impairments of nutrient digestion and/or absorption; Increased demands; Impairments of nutrient metabolism; Any modality of oncologic therapy induces hyponutrition occurrence, especially in those cases in which several therapies are administered to cure cancer (surgery, radiotherapy, chemotherapy). Hyponutrition in cancer patients produces a decrease in muscle mass, which leads to strength loss, having important consequences on functional status of the individual since it increases dependence on others (relatives, caregivers) and decreases quality of life. Besides, hyponutrition is associated to poorer response to radiotherapy and chemotherapy, or poorer tolerability of such therapies. Hyponutrition also impairs scarring mechanisms and increases the risk for surgical complications such as suture dehiscence or infections. Both infectious complications and surgically derived complications entail longer hospital staying, which contributes to increase management costs. Finally, effects of hyponutrition on mortality should not be neglected, with severe weight loss being associated to lower survival.