Effect of Patient-Controlled Transcutaneous Electrical Acupoint Stimulation on Quality of Life in Chronic Cancer Pain

Inclusion Criteria:

* Age between 18 and 80 years, regardless of gender;
* Diagnosis of primary or metastatic malignant tumor confirmed by histopathology and/or cytology, consistent with the American Cancer Society criteria for malignancy;
* Presence of cancer-related pain, defined as an average Numeric Rating Scale (NRS) score ≥ 2 over the preceding week or current regular use of opioid analgesics;
* Life expectancy ≥ 3 months;
* Eastern Cooperative Oncology Group Performance Status (ECOG-PS) score ≤ 2, stable vital signs, clear consciousness, intact pain perception, unimpaired communication, ability to cooperate with study procedures and complete assessments;
* Provision of signed informed consent by the patient or their legal guardian after comprehensive explanation of the study;

Exclusion Criteria:

* Pain not attributable to cancer;
* Severe cardiopulmonary dysfunction or respiratory depression;
* Implantation of cardiac pacemaker or metallic implants at stimulation sites;
* Local skin lesions or conditions unsuitable for TEAS at the acupoint sites;
* Severe psychiatric disorders or significant cognitive impairment;
* Concurrent participation in other clinical trials that may interfere with the outcome evaluation of this study;
* Previous history of transcutaneous electrical acupoint stimulation (TEAS) or transcutaneous electrical nerve stimulation (TENS);