Cannabis use among patients with cancer helped relieve pain and improve sleep quality as well as subjective cognitive function, a small observational study of 25 participants suggests.
Over a 2-week period, patients reported significant improvements in sleep quality from baseline as well as lower pain intensity, particularly among those reporting higher cannabidiol (CBD) use. Although cannabis use had minimal influence on anxiety or depression, patients reported being able to think more clearly.
“We thought we might see some problems with cognitive function,” senior author Angela Bryan, MD, professor of psychology and neuroscience at University of Colorado, Boulder, and a cancer survivor, said in a press release. But “we found that when patients’ pain levels came down after using cannabis for a while, their cognition got better.”
However, Donald I. Abrams, MD, who was not involved in the research, pointed out that “25 patients is not going to be a major practice changer.”
“It’s an observational study, it was started in 2018, so why was it so small?” asked Abrams, professor emeritus of medicine at the University of California, San Francisco, and integrative oncologist at the UCSF Osher Center for Integrative Medicine.
The authors explained that COVID-19 did interrupt the study initially, but that doesn’t fully account for the low patient numbers. First author Greg Giordano, MS, said that future research needs to expand on the cohort size and study period. “Studies should include larger and more diverse samples, as well as collect data over longer timeframes to be able to observe changes following sustained use,” Giordano, also of the University of Colorado, Boulder, told Medscape Medical News.
The study was published online on April 26 in Exploration of Medicine.
Cannabis use has been rapidly increasing in recent years and has become a popular option in palliative care. Cancer is an indication for medical cannabis use in most US states with comprehensive medical cannabis programs.
Surveys in the United States, Israel, and Canada have suggested that as many as 40% of people with cancer may be users. A recent survey of US patients with breast cancer, for instance, found that 42% were using cannabis, primarily to relieve side effects associated with treatment, such as pain, anxiety, nausea, and insomnia.
Although oncologists generally support cannabis use for adults and children with cancer, about one third say they feel “sufficiently informed” to provide recommendations to their patients. Cannabis research is complicated by its classification as a Schedule 1 substance under the federal Controlled Substances Act.
In the current analysis, Giordano and colleagues assessed how cannabis purchased legally at dispensaries in Colorado affected cancer symptoms and chemotherapy side effects. The team conducted an observational study with 25 patients who had been diagnosed with any type of solid tumor and had undergone or was undergoing either curative or palliative treatment.
The patients first had an initial appointment where baseline levels of pain, sleep patterns, and cognitive function were assessed and then, 2 weeks later, had an acute administration appointment that included assessments before cannabis use as well as 1-hour and 2-hours post-use.
During the 2-week period, patients consumed an edible cannabis product of their choice from a dispensary and used it as much or as often as needed or desired for 2 weeks without any instruction from research staff about dosing or frequency. Participants were also instructed not to use any other cannabis products during this period.
Participants completed self-report questionnaires about their pain and sleep quality, rating their sleep quality on a scale from 0 (very good) to 3 (very bad) and their average pain, ranging from 0 (no pain) to 10 (worst pain imaginable). Researchers also measured participants’ cognitive function with the Stroop task.
With sustained use, sleep quality improved from baseline to the acute administration appointment (baseline mean, 1.2; pre-use at acute administration mean, 0.87; B, -0.43; P = .02).
Pain intensity also improved from baseline to the acute administration appointment (baseline mean, 3.08; pre-use at acute administration mean, 2.48; B, -0.63; P = .02). Participants reporting higher CBD use showed steeper reductions in pain intensity.
When controlling for total tetrahydrocannabinol (THC) and CBD ingested, the authors observed a significant effect of time on pain interference (baseline mean, 53.43; pre-use at acute administration mean, 50.15; B, -3.99; P = .01).
The effect of cannabis use on anxiety and depression was marginal, with no significant interactions between cannabinoid level and either anxiety or depression and no overall change in general quality of life.
Sustained cannabis use was, however, associated with improvements in subjective cognitive function as well as reaction times, as measured by the Stroop task.
Unlike previous findings, the current study found that high CBD use among patients but not the psychoactive component, THC, was associated with stronger improvements in pain intensity and sleep quality.
That finding “contradicts” other studies that “found no benefit for CBD,” Abrams said. One recent randomized trial assessing 144 patients with advanced cancer compared CBD oil with placebo “found no improvement in symptoms compared with palliative care alone,” Abrams noted.
In addition to the small number of patients in the study, Abrams highlighted another limitation: Patients could use any kind and amount of edible they wanted, which left that factor “completely uncontrolled.”
Despite the study limitations, Abrams noted that cannabis has been used for thousands of years and as a researcher who has studied the health effects of medical cannabis extensively, “I’ve seen countless patients benefit from its use — mostly for symptom relief.”
“But right now, there is very little literature on the therapeutic benefits because of its status as a Schedule 1 drug,” Abrams said, and “that is a real barrier.”
Because “many oncologists don’t feel sufficiently informed to provide recommendations to their patients around cannabis use,” Giordano noted, patients may make “these decisions on their own.”
“We need more data about the potential benefits and harms of cannabis use to better inform patient and clinician decisions,” he said.
Funding for this study was provided by the University of Colorado Cancer Center. LPG is supported by a National Science Foundation Graduate Research Fellowship. The authors declare that they have no conflicts of interest. Abrams owns stock in Cannformatics and Lumen; he has received honorarium from Clever Leaves and Maui Grown Therapies, and speaker honorarium from GW Pharmaceuticals.
Explor Med. Published online April 26, 2023. Full text
Roxanne Nelson is a registered nurse and an award-winning medical writer who has written for many major news outlets and is a regular contributor to Medscape.
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