The purpose of this study is to compare the effects of dual acupoints and single acupoint transcutaneous electrical acupoint stimulation (TEAS) pretreatment on incidence of Post-Mastectomy Pain Syndrome(PMPS) in patients undergoing operation of breast cancer.

Patients were randomly assigned to three groups, receiving 30min TEAS before anesthesia respectively. The acupoints of dual point group are bilateral Neiguan points(PC6) combined with Danzhong point(RN17), single point group is bilateral Neiguan points(PC6), and the false stimulation group only attach electrodes without electric current. The frequency of TEAS is set to 2/15 Hz. Intraoperative anesthetic dosage of propofol and remifentanil was recorded. Three and six months after surgery, follow-up about chronic pain was made by telephone or face-to-face using the follow-up questionnaire. The adverse events were recorded.

Inclusion Criteria:

• Scheduled for operation of breast cancer；
• ASA（American Society of Anesthesiologists）I-II；
• Aged between 18 and 65；
• Informed consented。

Exclusion Criteria:

• Suffered from the contraindication of TEAS including the local skin breakage, infection or planted with the electrophysiology device；
• Unable to communicate and coordinate with the researcher, such as suffering from language comprehension deficits or mental diseases；
• Certain/suspicious addiction with alcohol, analgesics or other drugs；
• Unstable Angina or myocardial infarction occurred in 3 months; NYHA（New York Heart Association） is 3 or higher;
• Blood pressure ≥ 180/110 mm Hg while preoperative visiting;
• Suffered from diabetic complications including diabetic ketoacidosis, hyperosmolar coma, infection, macroangiopathy, diabetic nephropathy, retinopathy, cardiomyopathy, neuropathy and diabetic foot;
• Severe dysfunction of liver or kidney meaning one of ALT（Alanine Transaminase）, AST（Aspartate Transaminase）, ALP（alkaline phosphatase） or TBIL（total bilirubin） is 2 times higher that normal or creatinine clearance < 30 ml/min or serum creatinine > 177umol/L;
• Participate in the other clinical trial 3 month before the enrollment.

IPD including those about primary endpoint and secondary endpoints would be available to other researchers.

the data will become available after manuscript published, for 5 years.