More than half of all patients with cancer suffer from pain, which may be associated with both the disease and treatment. [1,2] Pain is generally at least moderate in intensity, may be chronic, acute, and episodic, and it impacts significantly on emotional wellbeing, disability, and quality of life. The prevalence of cancer pain increases as the disease progresses, such that around 80 % of those with advanced cancer experience moderate or severe chronic pain. [2-5] Cancer pain treatment

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... es, including those from the European Society for Medical Oncology (ESMO) [6], European Association for Palliative Care (EAPC)[7], World Health Organisation (WHO)[8], and National Comprehensive Cancer Network (NCCN)[9] recommend strong opioids as a first-line option and the mainstay of analgesic therapy for the management of moderate to severe cancerrelated pain. Nevertheless, despite it being so common and the availability of clear treatment guidelines, cancer pain is frequently poorly managed and poorly controlled. Reasons include patients' reluctance to report pain, poor treatment adherence, and fear of side effects. Physicians often feel insufficiently knowledgeable about pain management, concerned about opioid side effects, respiratory depression, and addiction, and afraid or unsure how to prescribe the higher-dose, high-potency opioid analgesics and/or combination therapies that may be necessary. [2,5,10,11] The side effects associated with opioids are well described and include nausea and vomiting, bloating, constipation, drowsiness, cognitive impairment, hallucinations, pruritus, myoclonus, urinary retention, postural hypotension and rarely respiratory depression and opioid-induced hyperalgesia. Many of these adverse effects are transient and may be addressed by the temporary reduction of opioid