Study protocol for the effect of intraoperative subanaesthetic dose esketamine on the incidence of postoperative depressive symptoms in patients with breast cancer: a multicentre, prospective, randomised controlled trial.

introductionPostoperative depressive symptoms are common after breast cancer surgery and can adversely affect recovery and quality of life. This multicentre trial aims to determine whether a single intraoperative subanaesthetic dose of esketamine, as an adjunct to antidepressant therapy, improves postoperative depressive outcomes at postoperative day (POD) 30. METHODS AND ANALYSIS: This multicentre, prospective, randomised, triple-blind, placebo-controlled trial will enrol 824 women aged 18-80 years with stage I-III breast cancer (American Society of Anesthesiologists physical status I-III) who are scheduled to undergo surgery. Participants will be randomised 1:1 to receive 0.2 mg/kg esketamine or an equivalent volume of normal saline after anaesthesia induction and before surgical incision. The primary outcome is the incidence of depressive symptoms at POD 30, assessed using the Hospital Anxiety and Depression Scale Depression (score ≥8). Secondary outcomes include acute and chronic pain, and anxious symptoms, etc. Primary analysis will use a generalised linear mixed model with a logit link on an intention-to-treat basis. ETHICS AND DISSEMINATION: The study protocol has been formally approved by the institutional ethics committee of the National Cancer Center (Approval No.25/483-5429). Written informed consent will be obtained from all participants prior to enrolment. Results will be disseminated through peer-reviewed journals and international scientific conferences. TRIAL REGISTRATION NUMBER: ChiCTR2600117573.