CBD in Treating Cancer and Related Symptoms
An Emerging and Alternative Therapy That Still Requires Much Investigation
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Gagandeep Brar, MD, is a board-certified hematologist and medical oncologist in Los Angeles, California.
Cannabidiol (CBD) is one of many compounds (called cannabinoids) found in the marijuana plant Cannabis sativa. CBD is known for its relaxing and pain-soothing effects.
CBD is non-psychoactive, so it does not give you the classic mind-altering euphoria or “high” felt from using marijuana—that effect comes from the cannabinoid called THC (tetrahydrocannabinol).
While the research is still very early, experts speculate that CBD may play a role in treating cancer, specifically by slowing tumor growth and inducing the death of cancer cells. CBD may also help manage unpleasant symptoms related to cancer and chemotherapy, such as pain, nausea, and vomiting.
CBD and Treating Cancer
There are a number of studies supporting CBD’s potential anti-cancer role—however, the majority are limited to in vitro and animal studies. For example, in various studies, there is evidence that CBD decreases the growth of lung and prostate tumors, provokes the cell death of colon, lung, and brain cancer cells, and reduces the spread (metastasis) of breast cancer.
While promising, large human clinical trials are needed to better understand whether CBD is truly effective in helping to treat cancer. Clinical trials would also allow experts to tease out issues like dosage, interaction with other cancer drugs, and CBD’s safety profile.
As of now, there are only a handful of human studies that have examined CBD’s anti-cancer role.
Here are a few examples:
- In one study of 119 cancer patients (most of the cancers were metastatic and traditional cancer therapies had been exhausted), CBD oil was given on a three day on and three days off schedule. In most of the patients, an improvement in their cancer was noted, such as a decrease in tumor size. No side effects from CBD were reported.
- In a case study, an elderly man with lung cancer refused traditional chemotherapy and radiation for his cancer treatment and instead, self-administered CBD oil. After one month of taking the CBD oil, a computed tomography (CT) scan revealed near-total resolution of his lung tumor along with a reduction in the number and size of chest lymph nodes.
- In another study, two patients with aggressive gliomas (a type of brain tumor) were given CBD capsules in addition to chemoradiation and a multidrug regimen. Both patients had a positive response to the treatment with no evidence of disease worsening for at least two years.
Keep in mind—these studies are extremely small and lack a control group, so no finite conclusions can be drawn from them. Nevertheless, they spark further interest in the possible role of CBD in treating cancer.
CBD and Treating Cancer-Related Symptoms
There is scientific evidence, although limited and not robust, that CBD, THC, or a combination of the two, may be effective in alleviating certain cancer-related symptoms, such as pain, appetite loss, and chemotherapy-induced nausea and vomiting.
For instance, the drugs Marinol (dronabinol) and Cesamet (nabilone), which are synthetic forms of THC, are approved in the United States for treating chemotherapy-induced nausea and vomiting. Research suggests that dronabinol may also improve the taste of food, appetite, sleep, and quality of life in cancer patients.
In addition, a mouth spray that contains both THC and CBD (called Sativex) is being investigated for its role in treating cancer pain (especially nerve-related pain) that is poorly controlled by opioids. The drug is currently not available in the United States, but it is available in Canada for treating advanced cancer pain.
Lastly, research has found that in the general population (so not necessarily patients with cancer), CBD can reduce anxiety and improve sleep quality. This finding is helpful, considering the diagnosis and treatment of cancer is often overwhelming and wrought with fear and worry.
With the potentially emerging use of CBD in treating cancer and/or its related symptoms, there are a few issues to consider.
CBD oil is perhaps the most commonly utilized formulation of CBD, as it’s easy to use and allows for a high dose of consumption. However, CBD comes in many other forms—gummies, tinctures, capsules, vapes, and ointments, to name a few.
Sorting out how to best administer CBD to patients with cancer may prove to be challenging, as various formulations may work or absorb differently.
While research suggests that CBD is generally well-tolerated, we need to more closely examine potential side effects in patients with cancer. In addition, we still do not know the long-term effects of taking CBD, or how it interacts with other medications.
Short-term side effects of CBD may include:
- Reduced or increased appetite
- Weight gain or loss
- Increase in liver enzymes
If CBD is combined with THC (in the form of medical marijuana), other side effects may occur, such as:
- Dry mouth
- Disorientation and confusion
- Loss of balance
While CBD by itself is federally legal (as long as the product is derived from hemp and contains no more than 0.3% THC), marijuana is not (although, it is legal in some states).
CBD is only available by prescription in the United States in the form of a drug called Epidiolex. This drug is used to treat refractory epilepsy.
Due to these legal conundrums, CBD products may not be as tightly regulated as hoped. With that, products that claim they have a certain CBD dosage may actually contain a different amount or even contain traces of THC. This is why it is important to only take CBD under the guidance of your personal healthcare provider.
A Word From Verywell
The prospect of incorporating CBD into cancer care is intriguing but still requires much more investigation. Until then, if you are considering trying CBD (whether you have cancer or not), it’s best to talk out the pros and cons with your healthcare provider.
Daily use of cannabidiol (‘CBD’) oil may be linked to lung cancer regression
It may be worth exploring further the use of cannabidiol (‘CBD’) oil as a potential lung cancer treatment, suggest doctors in BMJ Case Reports after dealing with a daily user whose lung tumour shrank without the aid of conventional treatment.
The body’s own endocannabinoids are involved in various processes, including nerve function, emotion, energy metabolism, pain and inflammation, sleep and immune function.
Chemically similar to these endocannabinoids, cannabinoids can interact with signalling pathways in cells, including cancer cells. They have been studied for use as a primary cancer treatment, but the results have been inconsistent.
Lung cancer remains the second most common cancer in the UK. Despite treatment advances, survival rates remain low at around 15% five years after diagnosis. And average survival without treatment is around 7 months.
The report authors describe the case of a woman in her 80s, diagnosed with non-small cell lung cancer. She also had mild chronic obstructive pulmonary disease (COPD), osteoarthritis, and high blood pressure, for which she was taking various drugs.
She was a smoker, getting through around a pack plus of cigarettes every week (68 packs/year).
Her tumour was 41 mm in size at diagnosis, with no evidence of local or further spread, so was suitable for conventional treatment of surgery, chemotherapy, and radiotherapy. But the woman refused treatment, so was placed under ‘watch and wait’ monitoring, which included regular CT scans every 3-6 months.
These showed that the tumour was progressively shrinking, reducing in size from 41 mm in June 2018 to 10 mm by February 2021, equal to an overall 76% reduction in maximum diameter, averaging 2.4% a month, say the report authors.
When contacted in 2019 to discuss her progress, the woman revealed that she had been taking CBD oil as an alternative self-treatment for her lung cancer since August 2018, shortly after her original diagnosis.
She had done so on the advice of a relative, after witnessing her husband struggle with the side effects of radiotherapy. She said she consistently took 0.5 ml of the oil, usually three times a day, but sometimes twice.
The supplier had advised that the main active ingredients were Δ9-tetrahydrocannabinol (THC) at 19.5%, cannabidiol at around 20%, and tetrahydrocannabinolic acid (THCA) at around 24%.
The supplier also advised that hot food or drinks should be avoided when taking the oil as she might otherwise feel stoned. The woman said she had reduced appetite since taking the oil but had no other obvious ‘side effects’. There were no other changes to her prescribed meds, diet, or lifestyle. And she continued to smoke throughout.
This is just one case report, with only one other similar case reported, caution the authors. And it’s not clear which of the CBD oil ingredients might have been helpful.
“We are unable to confirm the full ingredients of the CBD oil that the patient was taking or to provide information on which of the ingredient(s) may be contributing to the observed tumour regression,” they point out.
And they emphasise: “Although there appears to be a relationship between the intake of CBD oil and the observed tumour regression, we are unable to conclusively confirm that the tumour regression is due to the patient taking CBD oil.”
Cannabis has a long ‘medicinal’ history in modern medicine, having been first introduced in 1842 for its analgesic, sedative, anti-inflammatory, antispasmodic and anticonvulsant effects. And it is widely believed that cannabinoids can help people with chronic pain, anxiety and sleep disorders; cannabinoids are also used in palliative care, the authors add.
“More research is needed to identify the actual mechanism of action, administration pathways, safe dosages, its effects on different types of cancer and any potential adverse side effects when using cannabinoids,” they conclude.
Notes for editors
Please note: out of respect for patient confidentiality we don’t have the names or contact details of the cases reported in this journal.
Funding: None declared
Link to Academy of Medical Sciences labelling system
Externally peer reviewed? Yes
Evidence type: Single case report