Prospective Randomized Controlled Clinical Study of Acupoint Application With Gutong Plaster in the Treatment of Moderate to Severe Cancer Pain

Inclusion Criteria: 1. The subject has signed the informed consent form. 2. Age ≥ 18 years, including males and females. 3. According to the investigator's assessment, the subject has relatively stable cancer pain and requires continuous analgesic medication (estimated treatment duration ≥ 2 weeks). 4. Estimated life expectancy ≥ 3 months. 5. Eastern Cooperative Oncology Group (ECOG) performance status score of 0-3. 6. Adequate organ function. 7. Patients with moderate to severe cancer pain, defined as 4 ≤ NRS (Numeric Rating Scale) score ≤ 8. Exclusion Criteria: 1. Known allergy to any active ingredient or excipient of the study drug, or a history of allergy to other opioids and their related components. 2. Persistent pain caused by other diseases or unknown causes. 3. Subjects presenting with urgent symptoms such as intestinal obstruction/perforation, spinal cord compression, or pathological fracture. 4. History of severe psychiatric disorders, such as schizophrenia and depression. 5. Patients currently receiving chemotherapy or still in the chemotherapy reaction period (patients in the chemotherapy interval may be included. That is, patients who have completed chemotherapy for more than 1 week can be enrolled, or patients who have just finished chemotherapy may be enrolled at the investigator's discretion). 6. Patients who have received radiotherapy to the pain area within 4 weeks before enrollment (those who have received radiotherapy to areas other than the pain area may be included), or those who plan to receive radiotherapy to the pain area during the study. 7. Other conditions deemed unsuitable for participation in this study by the investigator, such as poor compliance.