How cannabis can help patients with cancer

Pipette with Cannabis oil against Marijuana plant

How Cannabis Can Help Patients With Cancer

By Dr Dan (Daniel Price MD)


When I first started learning about medical cannabis, I remember thinking that cannabis sounded a lot like snake oil. I wondered how it can treat everything: nausea, pain, insomnia, poor appetite, epilepsy, and many other symptoms and illnesses? Then it all made sense when I learned about the body’s own endocannabinoid system.

Our Body’s Endocannabinoid System

The endocannabinoid system is the most pervasive system in our bodies. It interacts with the other physiological systems to help maintain a healthy balance (homeostasis). The endocannabinoid system, a master system, acts like the symphony conductor who directs the individual musicians in an orchestra to together produce beautiful music. Disease often represents a system out of balance. For example, stress is a normal response, but anxiety represents a system out of balance; or auto-immune disorders, like Crohn’s disease, which indicates a normal immune system out of balance.

The endocannabinoid system is present in all vertebrates, from fish to humans. It was recently discovered in the 1980s and 1990s, and is still not taught in most medical schools. This explains why most physicians are unfamiliar with the endocannabinoid system, despite thousands of articles on the subject in the scientific literature.

The endocannabinoid system can be understood using a lock and key analogy. It is composed of endocannabinoid receptors on the surface of cells and within their mitochondria, which represent the locks. When keys, composed of chemicals called cannabinoids, are released and bind to the receptors, they unlock specific local effects. For example, when cannabinoids bind to the CB1 receptor, they can relieve nausea. “Endo”-cannabinoid keys are molecules produced by the body that fit the endocannabinoid receptors to help maintain balance. Two endocannabinoid keys have been discovered so far: anandamide, named after the Sanskrit word for “bliss”, and 2AG. Two endocannabinoid receptor locks, CB1 and CB2, have also been discovered. CB1 receptors are located primarily in the central nervous system. CB2 receptors are located throughout the body and are most prominent in the immune system.

The reason cannabis affects the human body is because chemicals within the plant (phyto-), called “phyto”-cannabinoids, fit into the endocannabinoid receptor locks. THC is the most common phytocannabinoid in the plant and is responsible for producing the psychoactive “high”, as well as modulating inflammation, pain, nausea, sleep, intraocular pressure, muscle tension, etc.

CBD is the second most common phytocannabinoid and is non-intoxicating. CBD works differently. It inhibits the breakdown of anandamide, thereby increasing the effects of this endocannabinoid. CBD modulates the effects of THC, including its psychoactivity, and can help patients remain more alert, clear-headed and functional. CBD is a very promiscuous molecule. In addition to interacting with CB1 and CB2 receptors to some degree, it interacts with dozens of different receptor systems throughout the body, including serotonin, opioid and dopamine receptors. This also helps explain cannabis’ broad range of effects.

Different people often have very different experiences with cannabis. A dose that may be effective for one person may not work for another. The reason for this is that everyone’s endocannabinoid system is unique. Because of this, a consultation with a physician experienced in the use of medical cannabis can be very helpful and is recommended, so that each patient receives an individual treatment plan and dosage.

Can Cannabis Cure Cancer?

In oncology, the word “cure” is reserved for patients who have survived 5 years without evidence of their tumor. Although the internet is filled with personal experiences and claims that cannabis can cure cancer, the answer to the question is: unknown at this point. We simply have no clinical research treating cancer in humans with cannabis. The reason for this is because, as of November 2020 when this article was written, cannabis is still classified as a Schedule I drug by the Food and Drug Administration, making it almost impossible to conduct human studies. It is imperative, therefore, that the FDA declassify cannabis and allow scientific research to move forward.


Dr. Donald Abrams, an oncologist and integrative medicine specialist at the University of California at San Francisco, a researcher and a world renowned authority on medical cannabis notes:

“[After] 33 years of being an oncologist in San Francisco, I would guess that a large proportion of the patients I have treated have used cannabis. If cannabis definitively cured cancer, I would have expected that I would have a lot more survivors. That being said, what we do know is that cannabis is truly an amazing medicine for many cancer and treatment-related side effects — nausea, vomiting, loss of appetite, pain, depression, anxiety, insomnia.”(1-2)

Dr. Abrams’ observation reflects a consensus within the oncology community: there is no doubt that cannabis is effective at treating cancer-related symptoms and treatment-related side-effects, however the jury is still out on whether cannabis can actually cure cancer (3).

Cannabis Effects on Cancer

While there are no human trials using cannabis to treat cancer, the National Cancer Institute now acknowledges cannabis has anti-cancer properties in preclinical research (4). In cell culture and animal studies, cannabis has been shown to impair the progress of cancer through multiple mechanisms. Cannabis limits the growth of tumor cells, in addition to inhibiting the growth of blood vessels that supply tumors. Cannabis also impairs cancer cells’ ability to invade tissue and spread metastatically. And finally, cannabis promotes programmed death of abnormal cells (apoptosis), which is disrupted by cancer cells.

Importantly, unlike chemotherapy and radiation, cannabis does not damage normal cells. In preclinical studies, CBD killed cells associated with breast cancer while having little to no effect on normal breast cells (5). In addition, studies have shown that CBD, when used with chemotherapy and radiation, may help make chemotherapy and radiation more effective and increase cancer cell death without adversely impacting normal healthy cells in breast and brain cancers (6-9).

Cannabis Helps Relieve Symptoms: Nausea & Vomiting, Appetite, Pain, Seep, Depression and Anxiety

Moving to more established uses of cannabis in helping to improve the lives of people battling cancer, we consider the alleviation of  symptoms of the disease, as well as side effects of various treatments. Nausea and vomiting associated with chemotherapy are often difficult to control even with the use of pharmacologic agents such as ondansetron. THC and CBD produce anti-nausea effects by binding to the CB1 and serotonin receptors respectively (10). They have been found to be effective in treating both acute and anticipatory nausea, which is notoriously difficult to treat, and for which there are no FDA-approved medications currently available. For many cancer patients, cannabis is the only remedy that relieves their nausea and vomiting. Additionally, CBDA and THCA, the acidic precursor forms of CBD and THC available as a tincture, have both been demonstrated to be effective and are non-psychoactive (11).

Poor appetite and weight loss are common in cancer patients and are often difficult to treat effectively. Many animal studies have previously demonstrated that THC and other cannabinoids have a stimulatory effect on appetite and increase food intake. Additionally, CB1 receptors in the hypothalamus in the brain may be involved in the motivational or reward aspects of eating (12).

Cancer-related pain can be caused by a swollen tumor, metastatic spread and side effects from other therapies, such as peripheral neuropathy due to chemotherapy. Cannabinoids relieve pain through brain, spinal, and peripheral modes of action (13). One study found that the efficacy of synthetic CB1 and CB2 receptor agonists (analogues of cannabinoids) to be comparable to the efficacy of morphine in a mouse model of tumor pain (14).

Cannabis has been found to be synergistic with opioids. Practically, this means a patient’s opioid dose can be decreased while improving effective pain relief and decreasing side effects such as nausea, constipation and risk of death in overdose. Cannabinoids have been shown to prevent chemotherapy-induced neuropathy in animal models exposed to paclitaxel, vincristine, or cisplatin (15-17), as well as relieving peripheral neuropathy pain, which can be very difficult to treat.

Sleep is a common problem for cancer patients for a variety of reasons, such as pain and anxiety. The endocannabinoid system has also been shown to play a key role in the modulation of the sleep-waking cycle in rats (18-19). While THC can initially be stimulating, its metabolites are more sedative. For this reason, it is recommended that patients use cannabis about 1 hour before going to bed to allow the sedative THC metabolites to accumulate.

While CBD is regarded as wake-promoting, it can help relieve both anxiety and pain, making it easier to relax, fall asleep and stay asleep. Preparations with a CBD:THC ratio of 1:1 have been shown to be effective and well tolerated because of CBD’s modulating effects on THC (20). The effects of cannabis in the form of a tincture or an edible will last about 4-6 hours for most people and produce little or no residual sedation the next morning, unless the dose is too high. Cannabis is often more effective than pharmaceutical options, and its safety profile is superior, with much less potential for dependence or withdrawal. Cannabis does not cause rebound insomnia or anxiety when discontinued, and in contrast to other sleep medications, there is no risk of fatal overdose (see above). Cannabinol (CBN), the cannabinoid produced from THC when cannabis is heated, can help make people feel sleepy without intoxication. CBN is available in many cannabis dispensaries

Anxiety and depression are understandable complications of cancer. THC likely produces anti-anxiety and mood elevating effects by binding to the CB1 receptor. CB1 receptors are particularly dense in the areas of the brain associated with anxiety: the amygdala, hippocampus, and prefrontal cortex. Caution is indicated however, because THC is characterized as being “biphasic”, meaning that low doses of THC (< 5 mg) can be calming and reduce depression, while high doses can worsen anxiety and depression and even cause panic attacks and paranoia.

CBD exerts its anxiolytic and antidepressant effects by binding to dopamine and serotonin receptors in the hippocampus and prefrontal cortex of the brain. CBD is considered the best choice for anxiety (21) and works particularly well during the day due to its nonintoxicating nature. Combinations of CBD and THC can also be an excellent option. The strongest research evidence supporting the use of cannabinoids to treat depression comes from many rodent models, which demonstrate that THC and CBD consistently give the same results as common antidepressants (22-25). Terpenes, chemicals that give the smell to plants, present in cannabis, such as limonene (prominent in citrus) and linalool (the active ingredient in lavender), also contribute to its antidepressant and calming effects.

A Human Study

Finally, let’s look at the results of a large, prospective, human study of the use of medical cannabis by 2970 cancer patients in Israel published in 2018. Overall, 96% of patients reported an improvement in their condition 6 months after beginning treatment with cannabis. Prior to treatment only 19% reported a good quality of life, but this rose to 70% after 6 months. The most improved symptoms included nausea and vomiting 91%, sleep disorders 88% and anxiety and depression 84%. Pain relief was also prominent, with 53% of patients reporting pain in the range of 8-10 before treatment with cannabis. This severe level of pain was reduced to only 5% after 6 months. Drug consumption was reduced in 35% of patients, including pain medications, sedatives and steroids. Of the 344 patients taking opioids initially, 36% stopped taking opioids and 10% were able to reduce their dose (26). This study shows that cancer patients instructed in the proper use of medical cannabis can significantly improve their lives with few side effects.


In summary, cannabis works on humans by interacting with the body’s own endocannabinoid system. While its ability to cure cancer has yet to be evaluated in clinical trials, laboratory data is promising. Of greatest benefit to patients is the symptomatic relief cannabis can provide for problems like nausea, vomiting, pain, insomnia, anxiety and depression. Cannabis is a very complex plant with powerful effects. For this reason, a consultation with a physician well versed in the use of medical cannabis is recommended to maximize the benefits to the patient and minimize any side effects. I am happy to help provide a thorough medical consultation for anyone interested and can be reached at



By Dr. Dan (Daniel Price MD)