The three-step pain relief for cancer was proposed by the World Health Organization in 1986 to treat cancer in three steps, which mainly include: 1. First step: for mild pain, non-opioid drugs, such as ibuprofen, are generally used to relieve mild pain; 2. Second step: for moderate pain, patients with relatively heavy pain can be treated with weak opioid drugs, such as prednisolone, tramadol, etc. to control and relieve pain; 3. Third step: for severe cancer pain, opioid drugs, such as morphine extended-release tablets, can be used to effectively control cancer pain and relieve patients’ pain. Because cancer pain is very painful for cancer patients, the World Health Organization currently manages pain as a type of disease, so it is important for cancer pain to be fully evaluated and effectively controlled to improve the quality of survival of cancer patients and reduce their pain.