PICC is usually used in oncology, especially in medical oncology, where many chemotherapeutic drugs can have an irritating effect on the surrounding blood vessels, causing pain in the patient’s veins during infusion, and some of the pain can be very severe. Also, if chemotherapy drugs are infused frequently, it may cause sclerosis of fine blood vessels; if some chemotherapy drugs accidentally leak into the skin around the blood vessels, it may cause skin necrosis or even failure to heal. Therefore, if a tumor patient needs to have a PICC tube for chemotherapy drug infusion, the end of the PICC tube is placed in the superior vena cava, which is relatively wide and will not be damaged during chemotherapy. In addition to chemotherapy drug infusion, there are some patients who can also consider PICC placement if they have long term infusion of intravenous nutrition drugs.