An Oncologist’s Perspective About Cannabis & Cancer

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Many cancer patients turn to cannabis for relief when traditional medicine isn’t enough. Dr. Paul Daeninck, medical oncologist and palliative care consultant at Cancer Care Manitoba, tells us how cannabis helps manage symptoms both during and after cancer treatment.

Cannabinoids have been used by cancer patients for years to help reduce nausea associated with chemotherapy. According to Dr. Daeninck, the first study was in 1975 and it showed that the cannabinoid THC was effective at decreasing nausea and vomiting. Many studies have since shown that herbal marijuana as well as synthetic prescription cannabinoids (such as nabilone and dronabinol) help with chemotherapy-induced nausea. Cannabis also helps with another type of nausea called anticipatory nausea, which is a learned or conditioned response to chemotherapy—the sights, sounds, and smells of treatment make you vomit. Studies conducted in animals and in the lab show that using a cannabinoid can actually prevent anticipatory nausea.

Loss of appetite can occur because of the cancer or because of its treatment. Many patients can’t tolerate eating and as a result have trouble with weight loss. There have been a number of studies using cannabinoids to help with appetites in cancer patients. “The hope was that we’d make them fat by giving them the munchies,” jokes Dr. Daeninck. What researchers discovered was that while patients don’t put on weight, cannabinoids slow down or stop weight loss.

Dr. Daeninck says that cannabis also helps patients who have nerverelated or bone/inflammatory-related cancer pain. Not only does the use of cannabis give patients better pain control, they actually sleep better—probably because the pain is under better control at night. When he and a medical resident followed 25 of his patients using cannabis, they discovered that they took fewer opioids (drugs like fentanyl, morphine, and oxycodone) on a daily basis. “In many cases, patients were dropping their dose and just feeling better overall.”

Anxiety can be overwhelming in people living with cancer. “Patients come to us and have difficulties with anxiety around diagnosis and the discussion. They even get anxious
thinking about cancer care,” says Dr. Daeninck. He found that his patients who use cannabis report an improvement in their anxiety.

The effects of cancer treatment can linger.

Cancer treatment is hard on the body and recovery can take a long time. Chemotherapy and radiotherapy can cause lasting nerve damage (called neuropathy) resulting in symptoms such as pain, numbness, and tingling in the hands and feet. Some of Dr. Daeninck’s patients use cannabis post-treatment to relieve their symptoms, improve their well-being, and get themselves to the point where they can go back to work. “Most of my patients are just trying to get on with life.”

Change must come to hospitals and palliative care centres.

Dr. Daeninck explains that hospital and palliative care centre staff need education to learn that cannabis isn’t dangerous. For many patients, cannabis is their medicine and it’s what works. Policies must be rewritten because they restrict the drugs that patients can bring in to the facilities. He says it’s a disservice to tell patients that they can’t use the medication that’s done the best for them. “We have to be aware that all of the medications that we have at our disposal in terms of palliative care are not panacea. They do help, they can work very well, but they also can have side effects. And many of these patients have been through the mill in terms of chemotherapy and radiotherapy.”

Personalized Therapy

Cannabis is a personalized medicine. 
It isn’t always clear what product or ratio of THC (delta-9-tetrahydrocannabinol) to CBD (cannabidiol) will provide you with the best symptom relief, which is why there is often a process of trial and error before finding the right fit. Doctors may be uncomfortable making recommendations on the dosing of medical cannabis, including the amount to try, how to deliver it, and which product might be right.

Starter Packs Are A First Step. Some licensed producers have developed a simple system to introduce patients to cannabis as a therapy. The starter program from CanniMed Ltd., for example, includes three varieties of cannabis with unique ratios of THC to CBD, a portable vaporizer, and an evaluation logbook to monitor symptom relief. Dr. Daeninck tells his patients to try a starter pack and then tell him what works for them and what doesn’t. “You can really hone in on what’s going to help that person.”

Start the discussion with your doctor.

One of the problems is that doctors just don’t know enough about cannabis as medicine. “Nobody actually says in medical school that medical marijuana is a viable alternative or this is what you should think about when you have patients where nothing else works.” If your oncologist isn’t comfortable prescribing cannabis, you can ask for a referral to a pain clinic. Dr. Daeninck sees a number of patients this way. He talks to them about why they want cannabis, whether it’s the right thing for them, if they’ve had any benefit (for those who have used marijuana), and how they could go about starting it (for those who are new to it).

Does cannabis cure cancer?

There’s a wave of people abandoning traditional cancer treatment for cannabis. Dr. Daeninck warns against it. “A lot of people have corrupted the message. You go to the Internet and the non-regulated producers say, ‘Hey, I’ll cure your cancer by giving you this marijuana.’ The trouble is that they’ve looked at some preliminary data and blown it out of proportion.” The truth is, he says, when you use some components of cannabis (e.g., THC or CBD), you can show some effect to cancer cells in a Petri dish. Some cells may die off, some may not produce as quickly, and some may not travel the way cancer cells do. But there’s no definitive research yet.

CanniMed Ltd. is one of Canada’s licensed producers of medical cannabis, and a CARP Recommended partner. To learn more about medical cannabis visit