Background: Various analgesic modalities are adopted for perioperative analgesia in breast cancer surgeries. Opioid-free and opioid-sparing techniques are gaining popularity due to the lack of opioid-dependent undesirable effects, including respiratory depression, urinary retention, nausea and vomiting, constipation, itching, opioid-induced hyperalgesia, tolerance, addiction, and immune system disorders. The goal of this prospective randomized clinical trial is to investigate the impact of opioid-free anaesthesia (OFA) versus conventional general anaesthesia (CGA) on postoperative analgesic requirements after breast cancer surgery (lumpectomy/mastectomy, with or without axillary lymph node excision). Secondary objectives include comparative perioperative evaluation of cognitive function and postoperative adverse events during the first 48 hours atfter surgery. Comparative evaluation of intraoperative haemodynamics and hospital length of stay are also secondary objectives, as well as the incidence of neuropathic pain assessed by validated questionnaires at 3 and 6 months postoperatively. During the preoperative screening, body measurements, age, gender, ASA (American Society of Anesthesiologists) physical status classification, educational level (using a 6-level scale: elementary, middle school, high school, higher education, higher education, and postgraduate/doctoral degree), home medication, and comorbidities (using the Charlson Comorbidity Index) are recorded. Intraoperatively, the duration of anaesthesia, duration of surgery, associated intraoperative data (e.g., haemodynamic instability, adverse effects associated with protocol-administered pharmaceutical agents, etc.), and medications administered (type and quantity) are recorded. The investigators expect to recruit at least 100 participants per group.