alive logo

Cannabis In Cancer Treatment

What is its current role?


Cannabis In Cancer Treatment

Becky Lee remembers being in shock when, in 2017, she found out she had breast cancer. Once she began learning about what lay ahead—a mastectomy, chemotherapy, and radiation—she decided to add cannabis to her strategies to cope with some of the intense side effects of treatment. The Vancouver-based working mom is glad she did.


Pain and stress relief

Now 51, Lee used cannabis to reduce pain from the removal of her breast and the nerve pain that accompanied radiation. The substance stimulated her appetite throughout chemotherapy; without it, she says, she wouldn’t have eaten very much. She consumed cannabis on days when the whole ordeal felt overwhelming. 

“I had a lot of anxiety,” Lee says. “There are so many layers to cancer. They throw a lot of medical information at you, and you’re worried about every decision you make. On low days, it made me feel calmer. 

“I also did things like exercise and meditation to deal with everything,” she adds. “But I found it [cannabis] really helped me throughout.”


Positive results spur research

Anecdotal reports such as Lee’s are common when it comes to the way medical cannabis can help people with the disease. As interest among patients has grown, more research is being done into the role that cannabinoids—the chemical compounds found in the resin of the cannabis plant—may play in cancer.

Dr. Pippa Hawley is spearheading that research in Canada. The medical director of the provincial pain and symptom management/palliative care program at BC Cancer led a study published in the journal Current Oncology that surveyed the state of cannabis use in cancer during August 2018, just over one month before federal legalization.

More than half of patients in that study had tried cannabis at some point, and almost one-quarter were currently taking cannabis to help manage their symptoms or to treat their cancer—even though evidence to support the latter is lacking. 

“What existing research shows is that the most common symptoms people use cannabis to address are pain, anxiety, sleep disturbance, and nausea.”


Research will help guide treatment

Patients and health care practitioners alike are seeking a better understanding of how best to incorporate cannabis into treatment plans. 

“The study came about because of the enormous number of cancer patients who are taking medical cannabis products for symptom management and other reasons,” Hawley says. “We felt we couldn’t guide the patients appropriately, because we don’t have enough information.”

Hawley and BC Cancer have applied to Health Canada to conduct the first national study on cannabis use in cancer. What existing research shows is that the most common symptoms people use cannabis to address are pain, anxiety, sleep disturbance, and nausea. 

“A lot of people are saying it helps,” Hawley says. “One would think they would have to derive benefit from it to bother with it, because it’s expensive and not usually reimbursed.” 

While some cancer patients may experience a beneficial effect from taking cannabis, there’s a dearth of research when it comes to dosages, safe usage, and potential adverse effects. 


Research to guide safe usage

Of patients using cannabis in the BC study, only 31 percent had medical authorization. Many obtained it “from a friend” or a dispensary, rather than from a licensed producer (LP) with proper labelling. (Although there are now some legal recreational cannabis dispensaries, all storefront medical cannabis dispensaries in Canada are as yet illegal.) The low rate of medical authorizations in the study suggests that few people had talked to their health care practitioner about cannabis use. 

“It’s not a harmless treatment,” Hawley says. “We don’t know what the risks are yet. It’s very much unknown.”

Some people who use cannabis for cancer hope or claim it will cure cancer, a point that concerns Hawley. Patients might ignore adverse effects or take dangerously high doses. 

What are possible side effects?

  • sleepiness
  • dry mouth
  • impaired short-term memory and coordination
  • anxiety or paranoid thoughts
  • can also interfere with the effects of other medications


Accessing medical cannabis     


From your pharmacy

For severe nausea and vomiting caused by chemotherapy, your doctor can prescribe a synthetic cannabinoid medicine in pill form (dronabinol or nabilone) and for intractable pain, a mouth spray purified and formulated from a standardized whole plant extract of the cannabis species Cannabis sativa L. (nabiximols). These are not covered by provincial drug plans, but they may be covered by some extended health plans.


From licensed cannabis producers

You can get plant-derived cannabis products from a list of approved licensed producers (LP) available through Health Canada. Your health care practitioner will have to complete a medical document on your behalf and you will need to contact an LP, who will mail the product to your home once the required forms are processed. You can find all the required forms by searching “Medical use of cannabis” at You may be able to claim the cost of these products on your tax return. 

“We don’t have human clinical trial results to say that it is safe or effective in treating cancer itself,” Hawley says. “We’re not saying it’s not worth looking at, but there’s a lack of evidence of effect.” 

Cannabis is never a first-line treatment, Hawley says. She may endorse patients trying cannabis if they’re having difficulty with side effects of conventional treatments or medications or if they’re overburdened by having to take so many pills (polypharmacy).  

For those who wish to use cannabis to manage cancer symptoms, Hawley urges them to talk about it with their health care practitioner.

“If they’re thinking of doing it, discuss it with their medical care providers,” she says. “They may find their health care professionals don’t feel altogether comfortable with it, which is not unexpected. It’s not because of ignorance but because cannabis hasn’t been fully tested. People should be open with their care providers.” 

Patients and health care practitioners alike are seeking a better understanding of how best to incorporate cannabis into treatment plans.”


Who should not use cannabis?     

  • anyone with a history of psychosis or who is confused
  • young people under age 25 with a long life expectancy (“There’s some evidence that high doses can impair cognitive development,” says Dr. Pippa Hawley.) 
  • people with a cardiac condition or unstable angina
  • pregnant women 


Other potential uses of medical cannabis   



Cannabis may help relieve pain and possibly reduce inflammation. Research, so far, has focused on animals, but there have been some anecdotal reports of noticeable pain relief, sleep improvement, and anxiety reduction.



Cannabis may help reduce the number and severity of seizures in some forms of the disease. Many more clinical trials involving cannabis are underway to learn more about how epilepsy patients can benefit.


Multiple sclerosis

Cannabis may help address muscle stiffness and spasms as well as sleep. Studies have also explored the effectiveness of cannabis for MS-related pain, including neuropathic pain and musculoskeletal pain.

Gail Johnson is a Vancouver-based writer, broadcaster, and fitness instructor. 

This article was originally published in the April 2020 issue of alive Canada, under the title "Cannabis in Cancer Treating."



Taking Care of the Body’s Supercomputer

Taking Care of the Body’s Supercomputer

Suzanne MethotSuzanne Methot