Awhile back, several colleagues and I wrote a review article about the role of cannabis during cancer treatment (if you’re curious about the review article, you can read it here. We also wrote about it for ASCO Daily News and were on their podcast).  Medical cannabis (aka medical marijuana) has been getting a lot of attention lately as it becomes increasingly available across the US. And there are some good reasons for this interest—it can be useful for managing a lot of symptoms, and there’s some preliminary evidence that it may have some role in enhancing immune function. It’s possible it may even have some effects on cancer itself (though we have a long way to go in that line of research).

I get a lot of questions about whether or not cannabis is useful during cancer treatment. It may not be for everyone, but I have seen it help a lot of people. There are a few important points to consider when thinking about cannabis.

First, the route of administration matters in terms of how the cannabis works. If it’s taken subligually or orally, it might take 60 to 75 minutes to work, but can last for five to seven hours. If it’s inhaled, it can start having an effect much more quickly (5 minutes), but the duration of the effect is much shorter (two or three hours). If it’s used topically, the effects start in one to two hours, and last somewhere between four and eight hours.

Second, the product itself matters. Marijuana contains cannabinoids. Most commonly, we talk about delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD). These compounds interact with the body’s endocannabinoid system. When choosing a product, it’s important to think about the relative balance of THC and CBD, as they have different effects on the body. Products can be synthetic (like dronabinol), made from whole plant extracts, or can be isolated extracts of THC and CBD.

Third, it’s worth noting that there are some risks with cannabis use. If it is inhaled, it has similar risks to tobacco smoke. There’s some concern that frequent and long-term use may increase cardiovascular risk. And in some instances, cannabis can worsen some mental health conditions. It can also impair concentration and memory. The side effects are most closely associated with the concentration of THC in the product.

There are some of the specific situations where cannabis tends to be useful:

Pain management- This is a major area, as pain can be difficult to manage in cancer. It’s probably one of the most common reasons people try it. Data are mixed in large studies, but many patients find it helpful.

Nausea and vomiting- This is another common issue that patients experience. Anti-nausea meds are usually part of cancer treatment. These include steroids (like prednisone), 5-HT3 antagonists (like ondansetron, aka Zofran), phenothiazines (like prochlorperazine, aka Compazine), and a number of others. Some patients have unpleasant side effects from these (common ones include constipation, worsened glucose control, dry mouth, etc, dependinging on the drug). Cannabis can be another tool in the toolkit here.

Appetite stimulation – Many people have some improvement in hunger, taste, and appetite (cannabis appears to increase levels of ghrelin and leptin, which are associated with hunger and appetite).  

Anxiety – While high levels of THC can make anxiety worse, CBD seems to be well tolerated and effective.

Sleep disturbances – Cannabis can likely improve sleep, especially if someone is also experiencing pain.  

Neuropathy – Neuropathy tends to be difficult to treat (I’ll write more about this in another post), but cannabis can be helpful for reducing the discomfort.

Cannabis is something to consider. In general, it’s a good idea to start with a low dose and slowly increase it as tolerated (especially for people who haven’t had much exposure to cannabis in the past).

1. Podcast: Guidance on Cannabis Use in Palliative Oncology. ASCO Daily News. https://dailynews.ascopubs.org/do/10.1200/ADN.22.0519/full

2. What Do Oncology Providers Need to Know About Cannabis Use in Patients With Cancer? ASCO Daily News.

3. Worster B, Hajjar ER, Handley N. Cannabis Use in Patients With Cancer: A Clinical Review. JCO Oncol Pract. 2022;18(11):743-749. doi:10.1200/OP.22.00080