Background: Opioid-based anaesthesia (OBA) has traditionally been used for perioperative analgesia in oncologic surgery; however, opioid-related adverse effects such as postoperative nausea and vomiting (PONV), respiratory depression, and increased opioid consumption have raised concerns. Opioid-free anaesthesia (OFA), employing multimodal non-opioid analgesic strategies, has emerged as a potential alternative aimed at improving postoperative recovery.

Objectives: To compare opioid-free anaesthesia with conventional opioid-based anaesthesia in patients undergoing elective oncologic surgery with respect to postoperative pain scores, opioid consumption, incidence of PONV, rescue analgesic requirement, and recovery parameters over the first 72 postoperative hours.

Methods: This prospective randomized controlled study included 60 adult patients (ASA I–III) undergoing elective oncologic surgery under general anaesthesia with thoracic epidural analgesia. Patients were randomized into two groups: OBA (n = 30) and OFA (n = 30). Postoperative pain was assessed using the Visual Analogue Scale (VAS) at 2, 6, 12, 24, 36, 48, and 72 hours. Total postoperative morphine consumption, incidence of PONV, need for rescue analgesia, intraoperative analgesic requirements, and PACU stay were recorded. Statistical analysis was performed using appropriate parametric and non-parametric tests.

Results: VAS scores were significantly lower in the OFA group at most postoperative time points (p <0.01). Postoperative morphine requirement was markedly reduced in the OFA group (1.30 ± 1.6 mg vs. 6.60 ± 1.3 mg; p < 0.0001), with fewer patients requiring opioids. PONV occurred in 60% of OBA patients and none in the OFA group (p < 0.0001). PACU stay was shorter in the OFA group without increased adverse events.

Conclusion: Opioid-free anaesthesia provides superior postoperative analgesia, significantly reduces opioid consumption and PONV, and enhances recovery in oncologic surgery, making it a safe and effective alternative to opioid-based techniques.

KEYWORDS: Opioid-free Anaesthesia, Opioid-based Anaesthesia, Oncologic Surgery, Postoperative Pain, Multimodal Analgesia, Postoperative Nausea and Vomiting.