The claim: Cannabis kills cancer cells
Cancer accounted for about 10 million deaths worldwide in 2020, according to the World Health Organization. One popular social media post suggests some of those deaths could have been avoided if cancer patients used cannabis.
A two-minute Facebook video shared Jan. 31 shows various images of the cannabis sativa plant. A voiceover describes the benefits of the plant, including its ability to treat cancer.
“Cannabis Kills Cancer Cells Without Damaging Healthy Ones!” reads the caption of the video.
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The post generated close to 1,400 interactions and 92,000 views in less than a week. Variations of this claim have amassed hundreds of likes on Facebook.
But the claim doesn’t tell the whole story.
Experts told USA TODAY that, while some studies have shown chemical compounds in cannabis can kill cancer cells, those findings have not been replicated in clinical trials involving humans. And while the Food and Drug Administration has approved cannabis-based products for the treatment of cancer-related side effects, they are not proven to cure cancer.
USA TODAY reached out to the social media users who shared the claim for comment.
Effects only shown in preclinical trials
Cannabinoids, chemical compounds in the cannabis plant, have long been demonstrated to kill cancer cells in test tube experiments, according to Dr. Donald Abrams, an integrative oncologist at the University of California-San Francisco.
However, these findings have not been replicated in clinical studies involving humans – the gold standard of medical research.
Dr. Christopher Holstege, chief of the division of toxicology at the University of Virginia, told USA TODAY he could find no ongoing clinical trials of cannabis as a treatment for cancer in humans. Studies also don’t typically use cannabis in its raw form, he said.
“Researchers tend to use more purified products as opposed to raw plant material in part because they want to know exactly what is being used in the study,” Holstege said.
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There are about 80 to 100 cannabinoids in the cannabis plant, with tetrahydrocannabinol (THC) and cannabidiol (CBD) being the main two, according to the Alcohol and Drug Foundation. Cannabinoids can interact with receptors in the nervous system and regulate cell activity.
The earliest published research on the anticarcinogenic effects of cannabinoids is a 1975 study that found the compounds inhibited lung adenocarcinoma cancer cell growth in vitro and in mice, according to a 2016 literature review. Preclinical studies published in later years also found cannabinoids inhibited cancer cell growth for conditions like breast cancer, melanoma skin cancer and thyroid cancer.
Some studies have shown cannabinoids eliminate cancer cells without damaging healthy ones, according to the National Cancer Institute. A 2021 study also found that extracts from the cannabis plant protect normal colon cells while reducing the viability of cancerous cells.
Those studies are promising. But there is still no “solid basis for ongoing claims by proponents of highly concentrated cannabis extracts or oils that these preparations can ‘cure cancer,'” according to a 2015 literature review published in the journal Clinical Pharmacology & Therapeutics. That’s still true today, Holstege said.
Cannabis isn’t a proven cancer cure
While research has indicated some compounds in cannabis can inhibit the growth of cancerous cells, that doesn’t mean it’s a cure. Cancer patients who rely on cannabis to treat their condition can face potential health risks, according to Holstege.
“You want to do the proven therapies, not unproven therapies, or you might die from your cancer,” Holstege said. “If you’re doing cannabis products, you really need to remember that there can be drug interactions that occur with other medications that you’re taking.”
Adverse side effects from taking cannabis products include drowsiness, sleepiness, blood pressure change, increased heart rate and nausea, according to the Memorial Sloan Kettering Cancer Clinic.
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“One problem with the public taking US cannabis products is that there is little quality control and you do not know what you are getting in the products purchased,” Holstege said.
Two commercially available cannabis-based drugs, dronabinol and nabilone, are FDA-approved “for the treatment of cancer-related side effects,” according to the National Cancer Institute. However, the FDA has not approved any cannabis products for the treatment of cancer itself.
Our rating: Missing context
Based on our research, we miss MISSING CONTEXT the claim that cannabis kills cancer cells. Preclinical studies have shown that cannabis compounds can kill cancer cells, but no clinical trials in humans have replicated those results. While some cannabis-based drugs are approved by the FDA to treat cancer-related side effects, experts caution that they are not a substitute for cancer treatment. They could also have some adverse side effects.
Our fact-check sources:
- Dr. Donald Abrams, Feb. 2, Email exchange with USA TODAY
- Dr. Adam Friedman, Feb. 2, Phone interview with USA TODAY
- Dr. Christopher Holstege, Feb. 5, Phone interview with USA TODAY
- National Cancer Institute, accessed Feb. 7, Cannabis and Cannabinoids (PDQ®)–Health Professional Version
- Clinical Pharmacology & Therapeutics, June 2015, Cannabis in cancer care
- Jama Network, June 23-30, 2015, Cannabinoids for Medical Use
- American Cancer Society, Aug. 4, 2020, Marijuana and Cancer
- Alcohol and Drug Foundation, Nov. 10, 2021, What is cannabis?
- Cancer Letters, Nov. 28, 2011, The antimitogenic effect of the cannabinoid receptor agonist WIN55212-2 on human melanoma cells is mediated by the membrane lipid raft
- Life Sciences, Oct. 1, 2015, Differential role of cannabinoids in the pathogenesis of skin cancer
- Current Oncology, March 2016, Anticancer mechanisms of cannabinoids
- National Center for Complementary and Integrative Health, November 2019, Cannabis (Marijuana) and Cannabinoids: What You Need To Know
- National Library of Medicine, March 2019, Learn About Clinical Studies
- Cancer Medicine, March 2018, The current state and future perspectives of cannabinoids in cancer biology
- National Institutes of Health, Jan. 19, 2019, False News of a Cannabis Cancer Cure
- Cancer Research, July 1, 2006, Cannabinoids induce apoptosis of pancreatic tumor cells via endoplasmic reticulum stress-related genes
- World Health Organization, Feb. 3, Cancer
- Oncogene, Aug. 28, 2008, JunD is involved in the antiproliferative effect of Delta9-tetrahydrocannabinol on human breast cancer cells
- The FASEB Journal, September 2003, Inhibitory effects of cannabinoid CB1 receptor stimulation on tumor growth and metastatic spreading: actions on signals involved in angiogenesis and metastasis
- Plants, March 17, 2021, Different Cannabis sativa Extraction Methods Result in Different Biological Activities against a Colon Cancer Cell Line and Healthy Colon Cells
- Memorial Sloan Kettering Cancer Center, June 29, 2021, Cannabis
- Journal of the National Cancer Institute, September 1975, Antineoplastic activity of cannabinoids
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