Cannabinoids Do Not Reduce Cancer-Related Pain, Has No Clear Effect on Sleep Problems

By Will Boggs MD

January 28, 2020

NEW YORK (Reuters Health) - Cannabinoids do not reduce cancer-related pain, and their effects on sleep problems in patients with chronic pain are unclear, according to a pair of new studies.

Up to 60% of patients undergoing anticancer therapy, and 90% of those with advanced disease report cancer-related pain. Surveys have found that many cancer patients resort to cannabinoids to address their pain, but reviews have found only very-low-quality evidence supporting their efficacy for reducing pain.

Dr. Jason W. Boland, who worked on one of the studies, a systematic review and meta-analysis, told Reuters Health by email, "Based on current evidence, cannabinoids (the active chemicals in medicinal cannabis) do not have a role in cancer-related pain."

Dr. Boland, of Hull York Medical School, University of Hull, in the UK, and colleagues found six randomized controlled trials relevant for evaluating the beneficial and adverse effects of cannabinoids, compared with placebo or other active agent, for the treatment of cancer-related pain in adults.

Change in pain as measured by a numeric rating scale did not differ significantly between cannabinoids and placebo overall and when only phase-3 studies were included in the meta-analysis.

Change in pain intensity, a secondary outcome in one trial, did not differ significantly between cannabinoids and placebo either, the researchers report in The BMJ Supportive & Palliative Care.

Cannabinoids generally carried a higher risk of adverse events, compared with placebo; in the meta-analysis, produced a 2.69-fold increase in the odds of somnolence (P<0.001) and 58% rise in the odds of dizziness (P=0.05), as well as nonsignificantly higher odds of nausea and vomiting.

Patients treated with cannabinoids had 33% higher odds of study dropout due to adverse events, compared with placebo, but this difference fell short of statistical significance.

In the other study, published in the same journal, Dr. Sharon R. Sznitman of the University of Haifa Faculty of Social Welfare and Health Sciences, in Israel, and colleagues examined the association between sleep problems and medical cannabis in 129 chronic-pain patients aged 50 years and older.

Compared with patients not using medical cannabis, those using medical cannabis were less likely to report waking up at night, but there were no differences between the groups in terms of sleep latency and early awakenings.

Among patients using medical cannabis, more frequent use was associated with more problems related to waking up at night and falling asleep.

"Cannabis may potentially help improve sleep, but it is also potentially true that long-term and frequent cannabis use may lessen the sleep-inducing effects of cannabis," Dr. Sznitman said. "Much more research is needed. We are only beginning to scrape the surface."

"Cannabis may be effective for treating sleep problems, but we are far away from a strong evidence base for this," she said. "Physicians may also speak to their patients who use cannabis long-term and frequently about the potential for cannabis to be related to poorer sleep."

Michelle Sexton, a naturopathic doctor at the University of California, San Diego, who recently surveyed cannabis users regarding its acute effects and withdrawal symptoms, told Reuters Health by email the Israeli study "supports what we see in our clinical practice at UCSD. I was surprised to see so many people reporting 'smoking' cannabis. Given that there are vaporizer devices, there is no need to smoke cannabis. Also, the pharmacokinetics of oral cannabis would lend itself better to maintaining sleep across the night."

"Overall, the safety profile of THC (delta-9-tetrahydrocannabinol) appears to be better than that of benzodiazepines, opioids, or other sleep medications," said Dr. Sexton, who was not involved in the new studies. "The beneficial effects of THC for sleep need further investigation."

Dr. Sexton added, "These subjects were using THC-dominant cannabis, not cannabidiol (CBD). This is important as the two molecules have no shared pharmacology and should not be expected to have similar pharmacodynamic properties. THC is an important medicinal component about which much more is known than CBD."

SOURCE: and BMJ Supportive & Palliative Care, online January 20, 2020.