The relationship between tumor and nutrition is a question that confuses many tumor patients and their families. Should doctors give nutritional support treatment to patients after they have tumors? Will nutritional support therapy really “nourish” cancer cells and accelerate tumor development? Without nutritional support, tumor can still grow wildly: Nutrient metabolism in human body is a complex process. Even if no nutritional support therapy is given to tumor patients, tumor still consumes energy in the form of vigorous glycolysis and damages the immune function of the body. In other words, even if a tumor patient does not eat or drink all day, the tumor can still grow wildly. Without nutritional support, there is no treatment: malignant tumor patients often have different degrees of malnutrition. Severe malnutrition causes patients to be unable to receive treatment such as surgery, radiotherapy and chemotherapy. Nutritional support therapy can help patients complete various tumor treatments, improve their quality of life and prolong their survival.