​​Many cancer patients take cannabis products by a variety of routes for relief of symptoms. A recently completed Canadian multi-centre clinical trial led by BC Cancer showed that approximately half of those trying medical cannabis oils for cancer-related symptoms will notice a meaningful benefit from at least one kind of oil extract, though the preferred kind of oil varies between individuals.  Multiple symptoms improved, particularly sleep, drowsiness, anxiety, pain and night sweats, but there were also improvements in nausea, breathlessness and appetite. Though there are some interesting animal and laboratory studies showing that medical cannabis-derived substances may have an effect on cancer cell growth, there is no good human clinical trial evidence that cannabis or any cannabinoid has any useful effect on cancer control. The medical role for cannabis and its derivatives in cancer care is currently therefore only in supportive care.

The cannabis plant produces a large number of active components and the relative amounts of each component in natural cannabis vary enormously from one strain to another. The main ones are tetrahydrocannabinol (THC) and cannabidiol (CBD). THC is most responsible for the psychoactive effects, via stimulation of receptors widely distributed throughout the nervous system, but has therapeutic effects in multiple other organ systems as well. CBD counteracts the psychoactive effects of THC and has independent non-psychoactive therapeutic effects. The study showed that some people find either THC or CBD separately to be most helpful for them, and some prefer a 1:1 mix of THC and CBD. It is therefore very important to know exactly what the THC and CBD content is in any products consumed.

THC and CBD levels in products from Licensed Producers (LPs) are required by Health Canada to be accurately described, so you can work out exactly what dose to take, but products bought from walk-in dispensaries may not be clearly or correctly labelled, even when they are listed as “licensed”, as they cater to the recreational market and are prohibited from giving medical advice. 

Medical cannabis is therefore not a single entity, however there are classes of similar products that can be grouped together under three categories:

1. ​​THC-predominant

2. CBD-predominant

3. Balanced mixes of THC and CBD​

​The best form of medical cannabis is an oil extract. These come in small bottles that can have child-resistant caps, do not look like candies or treats. They also do not have a strong smell. They are taken in drops held under the tongue until absorbed through the lining of the mouth, and take effect quite quickly. The effects usually last for 6-8 hours. The labelling should include the number of milligrams (mg) in the bottle and the volume, so that a concentration can be figured out. From the concentration you should be able to work out how much you should take as a starting dose. For most oils this will be a tiny volume, so you will need to draw it up into a small syringe to measure exactly the right amount. The licensed producer you buy it from should tell you how much to take according to the concentration (strength) of your chosen product. Remember that if you change from one product to another you have to check the concentration of the oils as there may be a substantial difference in the strength and you should stay with a consistent dose in mg in order to have predictable effects. This may be a smaller or larger volume than your prior product. There are even sometimes differences from one batch of a product to the next one.  ​

Smoking or vaporizing cannabis is not recommended because of possible lung damage and second-hand exposure to people nearby, as well as a strong smell. 

Oral (swallowed) products like gummies, brownies or capsules are the main source of accidental overdoses by children (and pets) and are not safe to have around the house. They also take a long time to take effect and to wear off, so it can take a long time to figure out if a product is helpful or not, and how much to take. 

Suppositories can be useful if the oil under the tongue route is not possible for some reason, for example having mouth sores from radiation or chemotherapy, or because of severe nausea, but there is no advantage to using that route in any other respect, and absorption is unpredictable. Even mild trauma to the anus or rectum can also be dangerous if you have a low immune system or you blood doesn’t clot properly, both quite common issues in people on cancer treatments.

There are some topical creams and ointments that can be of benefit for some individuals, however there is not much research on this form of cannabinoid therapy and it is not possible to make any recommendations about when to try one, what specifically to try, or how to apply it yet.

​Medical cannabis can be accessed by four different routes:

• Medical plant-based products from a Licensed Medical Producer (LP);

• Health Canada approved prescribable cannabinoids from a regular pharmacy;

• Medical products from a walk-in dispensary.

• Cannabis plants grown at home by an authorized user, or by a designated authorized grower;
  

The #1 Option: Licensed Producers​​​​​​

Legal medical cannabis plant-derived products are the best choice and can be purchased by mail order from a number of LPs. Up to date contact information on LPs is available on the Health Canada website. See the guide to how to do this to the right of this web page. It is a little complicated, but it is worth persevering with the process to be sure of getting quality product of known strength. Patients should register with their preferred LP and print out the medical authorization on the LP’s website. Then they should fill in the required personal information; and then give it to the physician/nurse practitioner for them to finish filling out and to submit directly to the LP. The medical document will include the period of use (days, weeks or months) and the maximum dispensed daily amount that should be provided to the patient and needs to be renewed at least annually. The prescriber should file a copy in the patient’s medical record. The LP will ship the order by mail in bland packaging so no one will know what is inside the package. If you don’t have a mailing address you can designate someone with an address to receive it on your behalf. ​

Prescribable Canna​binoids​​​

The two cannabinoids currently available by prescription in Canada are nabilone (Cesamet®) and nabiximols (Sativex®). Nabilone is a synthetic THC-like chemical which comes as a capsule for swallowing. It is usually prescribed starting at 0.5mg as needed, up to three times a day, and patients generally start with once a day, increasing if needed and if tolerated. Higher strengths are available. It is approved for chemotherapy-induced nausea and vomiting and can provide additive benefits to conventional prescribed anti-nausea medicines. 

Nabiximols is a standardized extract of cannabis containing 50% THC and 50% CBD, administered by spray to the inside of the cheek for absorption through the lining of the mouth. Nabiximols is usually prescribed as one spray as needed up to every 4 hours, adjusting according to effect. It is an alcohol-based extract and sometimes causes a burning sensation in the mouth. ​

Unlicensed Dispen​​saries​

Cannabis products are available for purchase in person from a large number of storefront dispensaries. The quality of service provided by the dispensaries varies markedly. Though there is some regulation, the licensing processes (federal and municipal) are complicated, and not all “licensed “ dispensaries have actually been approved by Health Canada for product quality and safety. There may be no controls on hygiene or product labelling and there may be contamination with moulds or pesticides. Staff may be not well-informed about medical use.  ​

Home-Grown or by authorized des​​ignated grower​

Health Canada regulations allows patients to grow their own cannabis for medical purposes, within some limits, or to designate another person to grow it for them. These growers have to register with Health Canada. This method is not recommended as it is very difficult to grow plants safely and the product may not be free of mould or other contaminants. It is also not possible to have it tested, so the amounts of THC and CBD in them will not be accurately known.

Many cancer patients report getting cannabis products “from a friend”, which should be considered as risky as home-grown. 

​The BC Cancer study showed that it was not possible to predict which kind of oil any individual might prefer, so it is a good idea to try to get a small amount of each of the three main kinds of oils (THC, CBD and 1:1) and try each one in turn, for a few days, and compare them. You might like to fill out a diary of how you feel each day so that you can look back and compare the effects of the oils, but in benefits and side-effects, so you can decide if any are worth carrying on with (~50% chance), and if so, which is the best one for you. If you are quite anxious you are more likely to prefer a 1:1 or just CBD oil to a just THC one, but it is worth trying all to be sure. ​​

​A reasonable starting dose of oil extract would be 2.5mg of THC, CBD or the two combined. ​

As an example, if you had an oil that was labelled as having 10mg of cannabinoid per millilitre (mg/ml), 2.5mg would be a quarter of a ml (0.25ml). This is equivalent to one twentieth of a teaspoon - impossible to guess by eyeballing it. ​If not provided, you can get a 1ml syringe from any pharmacy​. If it is a more concentrated oil, like 25mg/ml, it would be just drops. Work out what amount of oil you need to take to get 2.5mg of THC, CBD or the two combined, and start with that, adjusting according to effect. Up to 5mg would be not unexpected, but the smaller dose may be sufficient, and can cause side-effects, especially if you are not used to the effects of cannabis already. Start low, and go slow is a good general rule. For continuous symptoms during the day the study showed the most common schedule was three times a day, but some needed it more frequently, and for those taking it to help them sleep, a larger dose taken in steps over the evening was best. Most patients taking it for sleep find it works best when taken about an hour before bedtime. 

​Receipts from LPs can be declared as legitimate medical expenses on your tax return at end of the year on form T2201.

Nabilone and nabiximols are expensive, especially nabiximols (around $700 per prescription) and they are not covered by Pharmacare or the majority of extended health plans.

Receipts from walk-in dispensaries do not qualify as medical expenses for tax purposes.​

​​As with all medications, side-effects from cannabinoids are quite common, but usually quite mild, and resolve rapidly on cessation or dose reductions. Dry mouth and dizziness are common, as is tummy rumbling. Cannabinoids do not usually cause constipation. Sometimes people feel hungry with them. As with any medication that can help you sleep, you may feel drowsy if you take too much (for you) during the day. Adjust your dose to avoid this. 

​​Having a substance use disorder is not a reason to withhold access to medical cannabis during cancer care. Cannabis and cannabinoids have been shown to reduce cravings in a variety of substance use disorders and to substantially reduce the risk of opioid overdose deaths in jurisdictions where it has been legalized. They can be particularly helpful for patients who have challenges complying with cancer treatment due to a concurrent substance use disorder, and may work better than some conventional medicines for pain, for example opioids (like morphine, hydromorphone or oxycodone) that they may be relatively tolerant to already. Cannabinoids are also less likely to cause serious sedation than most sleeping pills and anxiety-relieving pills, and are much safer than these medications in overdose situations.​

• Medical Cannabis: What patients with cancer need to know​​
• ​​How to Look for a Medical Cannabis Licensed Producer Online
  

​​If y​​​o​u are lookin​g for an LP that makes an extract, type “extracts” in the filter items box at the top of the list and then press enter. This will move all of the LPs that make extracts to the top of the list. Not all LPs make extracts. Not all LPs sell to the public. If there is not a website link in the list, try another LP. ​​

• How-to-Access-Medical-Cannabis-from-Legal-LP​
  

• Health Canada
• MedicalMarijuana.ca (fee-based option)
• Medical Cannabis Clinical Trial​