The WHO three-step cancer pain treatment program is an internationally accepted drug treatment for cancer pain. 90% of cancer pain can be well controlled if the basic principles of the program are followed correctly. Five basic principles must be observed in drug administration: 1. oral; 2. regular; 3. stepwise; 4. individualized administration; 5. attention to specific details. NSAIDs are generally preferred for mild to moderate pain, commonly paracetamol, aspirin; if pain persists or increases, add (not replace) opioids to NSAIDs, such as codeine or hydrocodone; for persistent pain or pain initially manifesting as moderate to severe, opioid doses should be selected or increased and supplemented with “if necessary The dose of opioids should be increased, supplemented by “if necessary” increased doses, such as morphine preparations. In addition, when severe pain cannot be controlled (e.g., tumor-induced pressure symptoms, neurological destruction, or burning-like pain) additional adjuvant medications should be used, such as the anticonvulsant carbamazepine, the antidepressant amitriptyline, and dexamethasone. If continuous use of opioids is required, do not use pethidine (dulcolax) because of its short duration of action (only 2-3 h) and repeated use can cause central nervous system toxicity (tremor, confusion, seizures). Mode of administration There are various dosage forms of opioid analgesics. Whenever possible, strive for oral administration, and if the patient cannot take them orally, choose rectal or percutaneous noninvasive routes of administration, and finally, invasive administration.