Many family members of tumor patients will wonder why patients will gradually lose weight and be weak. This is tumor-induced malnutrition, which affects the treatment in mild cases and leads to significantly shorter survival time of patients in serious cases. Some patients, even if the tumor site is not in the digestive tract, will suffer from anorexia, early satiety, nausea, vomiting, etc., which will lead to emaciation and decrease of resistance; while the other part of patients, who do not have digestive symptoms, eat roughly the same as when they are usually healthy, but a part of these patients also have progressive weight loss. This is because the metabolism of the three major nutrients, protein, fat and carbohydrate, induced by the tumor is disturbed. Tumors stimulate the body to secrete interleukins 1 and 6, tumor necrosis factor TNFa, etc., which cause the body to produce a process similar to the inflammatory response, affecting the patient’s nutritional intake. On the other hand, treatments such as surgery and chemotherapy can also affect the nutritional intake of patients to a certain extent, thus inducing or aggravating malnutrition. In order to reduce the impact of these conditions, tumor patients should receive nutritional therapy after admission to the hospital, and you may hear the two most common words spoken by the medical staff of the Department of Nutrition – quantification. The so-called quantification is to standardize the intake of various types of food at each meal in nutritional therapy. For example: the number of cereals, meat, eggs, etc.. Another example: a bun for breakfast, then we have to express it as how big the bun (expressed in two), what filling (all meat? Full vegetarian? Half meat, half veggie? How many proportions of meat, how many proportions of vegetables, etc.), and this is the process of quantification. Quantification is mainly to more accurately assess the intake of various nutrients and energy, to determine whether it is necessary to adjust the diet and nutritional treatment plan, to ensure that the patient is in a state of energy balance, to improve the organ function and immune status of the body, to alleviate the toxic side-effects caused by antitumor treatment, to improve the quality of life of patients with tumors, and to prolong the survival time. When patients are determined to need nutritional therapy after standardized nutritional screening and nutritional assessment, the nutritional therapy pathway should be solved firstly, and they should try to eat orally if they can, when there are chewing, swallowing, and consciousness obstacles they can go through nasogastric tube, nasoenteric tube, gastrostomy, enterostomy, and other pathways to carry out enteral nutritional therapy. When gastrointestinal dysfunction, parenteral nutrition therapy is needed through the intravenous route. The general principle: the intestinal tract can be used intestinal, intestinal insufficiency of parenteral supplementation. Enteral nutrition is the preferred treatment route. Although enteral nutrition and parenteral nutrition treatment pathways are different, but the same is that all the nutrients given should be balanced and reasonable, in line with the metabolic characteristics of the human body’s physiological and pathological state.