Pathophysiology of metabolic changes and malnutrition in colorectal cancer’s patients

Abstract: Metabolic changes, mostly leading to malnutrition, are common in colorectal cancer (CRC) patients and can jeopardize therapeutic actions, outcomes, and quality of life. Both, the cancer itself and the administered medical and surgical treatments can impair patient’s metabolism. Indeed, all the cancers produce inflammatory molecules that interfere with hunger and satiety mechanisms, such as tumor necrosis factor α, interleukins, calcitonin gene-related peptide, or insulin-like growth factor-1. Moreover, CRC affects nutrients absorption through bowel epithelium disruption and dysregulation of intestinal microbiota composition. Medical and surgical treatments furtherly contribute to metabolic changes, accelerating metabolic status impairment and ultimately leading to malnutrition. Chemotherapy and radiotherapy reduce appetite but also intestinal absorption, mainly because of the cytotoxic effect that alter the regenerative capability of the mucosa. Surgical resection alters the microbiota composition and induces an inflammatory response that generates a catabolic state capable to change the metabolism of glucose, lipids, proteins, and nucleic acids. Furthermore, it reduces or alter the surface of absorption of the bowel. A comprehensive knowledge and early diagnosis of the metabolic changes affecting CRC patients during their treatments, is crucial to prevent malnutrition, and ultimately to permit the best therapeutic regimen. The present review examines the pathophysiology of metabolic changes in this group of patients and offers an overview of strategies aimed to reduce their impact on patients’ health, to improve clinical and oncological outcomes, and quality of life.