Precautions before chemotherapy are as follows: 1. Fully communicate with patients and their families before chemotherapy, informing them of the precautions and possible side effects of chemotherapy to reduce their psychological burden; 2. Review blood routine, liver and kidney function, blood coagulation, electrocardiogram and other tests before chemotherapy to assess cardiac function and determine whether chemotherapy can be tolerated, and conduct tumor marker testing to facilitate comparison of treatment effects before and after chemotherapy; 3, Chemotherapeutic drugs are irritating to blood vessels, so it is recommended to place a deep vein tube before chemotherapy to avoid tissue damage caused by extravasation of chemotherapeutic drugs; 4. Fully understand the patient’s past medical history and current condition before chemotherapy, and formulate a specific chemotherapy plan according to the specific situation; 5. Calculate the patient’s height, weight and body surface area, and calculate the dosage of chemotherapy drugs according to the body surface area. Before chemotherapy, you can eat nutritious, high-protein and high-fiber foods to facilitate recovery.