Cancer Pain in the UK
Cancer pain is one of the most significant and undertreated clinical challenges in oncology. In the UK, there are approximately 375,000 new cancer diagnoses each year. At the time of diagnosis, around 30 to 40% of cancer patients experience significant pain, rising to 70 to 90% in advanced stages. Cancer pain arises from multiple mechanisms: direct tumour invasion of bone, nerve, or soft tissue; inflammatory mediator release; and treatment-related pain including chemotherapy-induced peripheral neuropathy.
Even with optimised opioid therapy, up to 30% of cancer patients experience refractory pain, and the side-effect burden of high-dose opioids significantly reduces quality of life. For patients who have reached the limits of conventional analgesia, cannabis-based medicines represent a clinically valid and evidence-supported option.
Cannabinoids and Cancer Pain Mechanisms
The mechanisms by which cannabinoids relieve cancer pain are multifaceted:
- Peripheral analgesia: CB1 and CB2 receptors are expressed on sensory neurons and at sites of tumour-induced inflammation. Cannabinoids reduce nociceptor sensitivity and inflammatory mediator release.
- Spinal analgesia: In the dorsal horn of the spinal cord, CB1 activation suppresses the synaptic transmission of pain information.
- Supraspinal modulation: The periaqueductal grey and rostral ventromedial medulla, key centres of descending pain modulation, are rich in CB1 receptors. Cannabinoid activation enhances descending inhibitory control of pain.
Clinical Evidence
- A pivotal Phase III trial of nabiximols (Sativex) in advanced cancer patients with uncontrolled pain despite optimised opioid therapy found significant pain reduction versus placebo, establishing proof of concept for the opioid-sparing approach.
- A 2022 systematic review in British Journal of Cancer analysed 11 RCTs involving 1,815 cancer patients and found cannabinoids were associated with a significant reduction in pain intensity and a higher proportion achieving meaningful pain reduction.
- UK registry data from Drug Science shows that cancer patients prescribed cannabis-based medicines report meaningful improvements in pain, nausea, appetite, and sleep.
Opioid-Sparing Potential
One of the most clinically significant potential benefits of medical cannabis in oncology is opioid dose reduction. Real-world data from several countries suggests that cannabis co-prescribing is associated with meaningful reductions in opioid requirements, allowing patients to maintain pain control at lower opioid doses with consequent improvement in alertness, bowel function, and overall quality of life.
Chemotherapy-Induced Nausea
Nabilone, a synthetic cannabinoid, holds a UK licence for the treatment of nausea and vomiting caused by cytotoxic chemotherapy that has not responded to conventional antiemetic agents. For patients experiencing inadequate CINV control with standard treatments, a specialist may consider a cannabis-based medicine as an adjunct antiemetic.
Access and Prescribing Pathway
Cancer patients wishing to access medical cannabis in the UK should request a referral to a specialist in pain medicine, oncology, or palliative care with experience in cannabis-based medicines. Cannamedical Britannia works with a network of GMC-registered specialists who can provide prompt consultation and, where appropriate, issue a Schedule 2 controlled drug prescription fulfilled via a licensed UK pharmacy.