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Medical cannabis reduces opioid use in cancer-related pain, research finds

Medical cannabis use among those with cancer-related pain is safe and effective and also reduces opioid consumption, according to a new study published in the BMJ.

In a previous systematic review of 52 studies, some 59% of patients undergoing anti-cancer therapy reported experiencing pain. The World Health Organization recommends the use of NSAIDs, paracetamol or opioids, either alone or in combination, for initial pain management in cancer. In addition, opioids are the preferred treatment choice for ongoing pain relief.

However, emerging data points to an important adjunctive role for medical cannabis (MC) in treating cancer-related pain in those using opiates. MC use also reduces both opioid and benzodiazepine use in patients with intractable pain. But the extent to which MC reduces pain medication use in those with cancer in real-world studies is still unclear.

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‘MC is safe and effective’

In the current study, Canadian researchers analysed registry data to determine if medical cannabis could reduce both pain and pain medicine use in cancer patients. Information on the use of MC products was collated as either cannabidiol (CBD) dominant, tetrahydrocannabinol (THC) dominant or CBD-THC balanced. Outcome measures regarding MC use included the brief pain inventory (BPI) assessed at baseline and after three, six and nine months. The medication quantification scale (MQS) assessed medication burden over time and the morphine equivalent daily dose (MEDD), considered the opioid-sparing effect of MC use.

There were 358 cancer patients experiencing pain and with available data for analysis. Significant decreases in BPI scores occurred from baseline to month nine (5.5 vs 3.6, p < 0.01). Overall pain severity scores also reduced from baseline over this time frame (3.7 vs 2.4, p < 0.01). Medical cannabis use lowered MQS in 26.2% of patients after nine months. Similarly, MEDD scores reduced in 14.3% of patients after nine months.

Only two serious adverse occurred with both considered unlikely to be caused by medical cannabis. The authors also observed better pain relief among patients using balanced CBD-THC products.

The findings led the authors to suggest that medical cannabis is a safe and effective complementary treatment for cancer-related pain. They called for randomised controlled trials to confirm these findings.

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