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Cannabis and Cancer: Facts vs. Myth

January 2, 2020

Cannabis and Cancer_Facts vs MythThe use of cannabis has exploded across the country and in Maine with recent laws permitting medical and/or recreational use. The term cannabis refers to two main categories of the plant; marijuana and hemp. The THC content determines if a cannabis is categorized as marijuana or hemp. Hemp is legally defined as a cannabis containing up to 0.3% of THC while marijuana contains more than 0.3% THC. All cannabis is now considered Cannabis sativa. Marijuana continues to be listed as “sativa” or “indica” but the distinction is based on biological effects rather than botanical differences.

The 2018 Farm bill legalized the production and sale of Hemp in the U.S. while marijuana remains federally illegal. At the state level, currently 22 states allow for medical use of marijuana and an additional 11 states and DC permit recreational use. Maine permits both medical and recreational use of marijuana.

Date Action
1913 Initially prohibited
1976 Possession of small amounts decriminalized
1999 Medical Marijuana law passed
2016 Marijuana Legalization Act; recreational use permitted
2017 Governor LePage vetoed a bill for practical implementation of the 2016 Law
2018 State Legislature overturned LePage veto
2019 Governor Mills enacted rules for full implementation of 2016 Law


The human body produces cannabinoids naturally, endocannabinoids, which bind to cannabinoid (CB1/CB2) receptors found throughout the body. The Endocannabinoid system assists in maintaining balance through regulation of the neurological system, hormones, and immune function.

Cannabis contains over 400 constituents including cannabinoids, terpenes, and flavonoids. THC (Delta-9-tetrahydrocannabinoid) and CBD (Cannabidiol) are the most well known and most prominent cannabinoids found in cannabis. Cannabinoids bind to CB ½ receptors and elsewhere to exert multiple effects throughout the body, acting both individually and as a group.

Biological Effects of Cannabis


  • Muscle relaxant
  • Anti-nausea
  • Appetite Stimulant
  • Anti-inflammatory
  • Analgesic
  • Anti-depressant
  • Anti-seizure
  • Lowers Blood pressure
  • Anti-spasm/tremor


  • Muscle relaxant
  • Anti-nausea/vomiting
  • Anti-inflammatory
  • Analgesic
  • Anti-anxiety
  • Anti-psychotic
  • Anti-seizure
  • Nerve protector
  • Anti-spasm
  • Blood sugar regulation
  • Reduction of panic attacks
  • Anti-oxidant
  • Anti-microbial
Although the current state of the evidence is insufficient to support cannabis as a cancer treatment, future studies may demonstrate benefit.


Claims asserting the curative powers of cannabis exist everywhere. The popularity of cannabis as a cancer cure has grown exponentially with increasing legality. Anecdotal reports of cures, alongside questionably safe instructions for use and production of highly concentrated cannabis oil, abound online. Unfortunately, current research does not support these claims. First/second/third-hand stories of someone curing their cancer with cannabis oil doesn’t constitute scientific evidence and should not be used to determine one’s cancer treatment.

Anecdotal evidence (i.e. individual stories) lacks an unbiased assessment and evaluation of effectiveness. One person’s experience can’t be broadly applied because each person and every type of cancer is unique. In addition, stories rarely disclose or detail the full clinical picture, which is necessary for determining the effectiveness of a therapy. Finally, anecdotal stories published online do not go through any verification or vetting. The truthfulness and accuracy of these stories is impossible to assess.

Research is broadly categorized into four tiers. From weakest to strongest they are:

  • in vitro (i.e cellular studies/ test tube)
  • Animal studies
  • Human observational
  • Human experimental

In vitro studies comprise most of the data supporting the claims made about cannabis curing cancer. As the weakest form of scientific evidence, in vitro studies do not reliably predict clinical response or efficacy. Animal studies showing anti-cancer effects of cannabis are promising. However, extrapolating clinical response from animal studies is challenging. The route of administration (direct injection into the tumor) and dose used in the animal studies may not be reasonable or realistic for people. There are only a few, small human trials assessing the efficacy of cannabis on tumor growth, and they are inconclusive.

The legal restrictions on cannabis, historically preventing scientific exploration of its therapeutic benefits, is slowly changing. Although the current state of the evidence is insufficient to support cannabis as a cancer treatment, future studies may demonstrate benefit. However, until more human trials are conducted, cannabis as a primary treatment for cancer is not recommended.

Alternatively, multiple studies show improved quality of life and reduced symptoms associated with cancer and cancer treatment from cannabis.

1. Pain: Pain is the most frequently cited purpose for medical cannabis use in the U.S. Human cannabis trials consistently show reduction in chronic pain. The National Academies of Sciences, Engineering, and Medicine (NAS) 2017 summary report concluded that, “there is substantial evidence that cannabis is an effective treatment for chronic pain in adults.” Concurrent use of cannabis with opioids reduced number of opioids used, and improved pain reduction.

2. Insomnia: Sleep disturbances related to cancer diagnosis and/or treatment occur frequently. The NAS 2017 report found moderate evidence supporting the use of cannabis to address sleep disorders. The causes of insomnia likely impact the efficacy of cannabis; insomnia due to pain may respond better than insomnia from hormone imbalances.

3. Gastrointestinal Benefit: Cannabis improves digestive complaints and gastrointestinal disorders associated with cancer treatment and diagnosis. Two literature reviews found that cannabis was superior to placebo, and comparable to conventional medications, for controlling chemotherapy-induced nausea and vomiting. Although the data remains limited in assessing the efficacy of cannabis for weight loss and reduced appetite in individuals with cancer, a recent pilot study found improvement with standardized THC capsules. The study is small and not placebo-controlled but builds upon previous animal studies. Based on the demonstrated benefit in irritable bowel syndrome (IBS)-diarrhea, cannabis may also benefit diarrhea due to cancer treatment.

4. Mood: Mood management is another common indication for using cannabis. Anxiety impacts many individuals diagnosed with cancer and undergoing treatment. According to the literature, there appears to be benefit in reducing anxiety and improving post-traumatic stress disorder (PTSD). An increase in depression has been seen in recreational cannabis users. It’s unclear if cannabis caused the depression or was more frequently used by depressed individuals. Regardless, if depression symptoms develop or worsen, cannabis should be discontinued.

Although generally well-tolerated in adults, cannabis should be used with caution and under the supervision of a qualified medical provider. Cannabis use is contraindicated in pregnant and lactating women as it may cause reduced fetal growth, delayed development, and contribute to childhood illness. Children and adolescents should also avoid use unless under the care of a qualified medical professional. Individuals with the following conditions should avoid cannabis or seek medical advice prior to use: Hepatitis C, unstable cardiac disease, psychosis, and/or lung disease.

Cannabis may interact with some medications increasing side effects and/or decreasing efficacy of the medications. Concurrent use with medications should only be done under medical guidance. Because cannabis affects cognitive function, motor skills, and reaction time; avoid cannabis use prior to/during operation of a motor vehicle.

In addition to the targeted therapeutic effect, medical cannabis may cause additional undesired effects.

  • Panic
  • Paranoid reaction
  • Increased heart rate
  • Dry mouth
  • Nausea/vomiting- chronic use
  • Short-term memory loss
  • Impaired cognitive function
  • Reduced sperm counts
  • Allergic reactions
  • Dizziness
  • Impaired motor function

Cannabis is a reliable therapeutic option for the management of cancer-related symptoms. Currently, insufficient evidence exists to support using cannabis as a primary treatment for cancer. Medical cannabis should be used under the guidance of a qualified medical provider to ensure safety.

Renée Lang, ND, FABNO, MPH is licensed as a naturopathic doctor in the state of Maine and is board certified in naturopathic oncology (FABNO). She received her naturopathic doctorate from National College of Natural Medicine in 2003 and holds a B.S. in Conservation and Resource Studies from the University of California at Berkeley. In addition, she received her MPH in 2013 from Johns Hopkins Bloomberg School of Public Health, with additional certification in environmental and occupational health. As a Reiki Master and Shamanic practitioner, Dr. Lang has been incorporating these healing techniques in her since 2002. Dr. Lang currently sees patients at her office in the Parkview Office Building in Brunswick, ME. From 2009-2013 she worked as a naturopathic oncology consultant at the Cancer Treatment Centers of America (CTCA) in Philadelphia. While at CTCA, Dr. Lang provided integrative naturopathic care to thousands of individuals with cancer.
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