Cancer is a collective term for a large group of diseases that may occur in various parts of the body. It is possible for cancer patients to lose weight continuously due to higher consumption, but not all cancer patients will lose weight continuously. There are some cases that after anti-tumor treatment, such as radiotherapy, with better dietary and nutritional improvement, it is possible that the weight will not decrease but will gradually increase, indicating a more obvious improvement in nutritional status. Cancer consumption is relatively large, if the patient’s diet and nutrition cannot keep up while doing anti-tumor treatment, in this case, there may be no way to continue to tolerate radiotherapy, and the patient’s weight will gradually decrease, which is a bad performance and may lead to a decrease in patient’s resistance, the outbreak of disease and recurrence of metastasis. Therefore, it is necessary to strengthen nutrition.