Study of the Effects of Transcutaneous Vagus Nerve Stimulation on Cancer Patients

Patients diagnosed with breast cancer who received assisted radiotherapy were recruited and the transcutaneous auricular vagus nerve stimulation (taVNS) was applied. The aim of of study is : 1) to study whether taVNS could improve the patient's fatigue, quality of life under radiotherapy or chemotherapy; 2) to investigate the effects of taVNS on the levels of patients' lymphocyte subsets and proinflammatory cytokines.

A prospective, randomized, double-blind, parallel controlled trial was conducted. This trail is to recruit 261 patients. Patients were randomly assigned in 2:1 ratio to two groups: 1) taVNS with conventional radiotherapy(intervention group); 2)sham taVNS with conventional radiotherapy (control group). taVNS was conducted at every radiotherapy day. taVNS stimulation method: for taVNS group, the electrodes were attached to the tragus of left ear after skin preparation with an alcohol pad, the stimulation current was a single-phase rectangular pulse with the following stimulation parameters: duty circle: 60 s "on" periods and 10 s "off" periods; frequency: 30 Hz; pulse width: 200 μs; pulse amplitude of 0.5 mA to 1.5 mA; stimulation time:30 min. For staVNS group, the clip electrodes were also placed on the left tragus but with no current output. The Fatigue Scale (BFI), the European Organization for Reasearch and Treatment of Cancer Quality of Life Questionnaire(EORTC QLQ-C30), Pittsburgh sleep quality index (PSQI) and Hospital Anxiety and Depression Scale (HADS) assessment, lymphocyte subpopulations,level of proinflammatory factors, blood routine testing and electrocardiogram testing were performed within 2 weeks before treatment (baseline), 4 weeks after intervention, end of chemoradiation and 1 month after the end of chemoradiation; weekly blood routine testing during intervention under radiotherapy and chemotherapy; the incidence of side effects and sleep quality score were evaluated at baseline, 2 weeks and 4 weeks after the intervention, at the end of radiotherapy and chemotherapy, and 1 month after the end of radiotherapy. The number of recruited participants met the statistical requirements.

Eligibility Criteria:
Inclusion Criteria:

1. Participants diagnosed with breast cancer, suitable for adjuvant radiotherapy after surgery;
2. Eastern Cooperative Oncology Group (ECOG) physical condition score: 0\~1 point.

Exclusion Criteria:

1. Participants with organic brain lesions (cerebral hemorrhage, large-area cerebral infarction, encephalitis, epilepsy, etc.);
2. Participants with peptic ulcer, arrhythmia, or cardiac corrected QT interval\> 450ms;
3. Participants who have slow breathing (less than 10 breaths per minute);
4. Participants who are or have been diagnosed with other major diseases (coronary heart disease, pulmonary heart disease, etc.);
5. Participants who are currently or have been diagnosed with mental disorders other than major depressive disorder;
6. Participants who are or have participated in vagus nerve or transcranial electrical stimulation treatment for less than 3 months;
7. Participants who are not suitable for vagus nerve stimulation treatment;
8. Participants who refuse to sign informed consent.