Medical cannabis safely helps alleviate cancer-related pain, may reduce opioid use
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Medical cannabis can safely help alleviate cancer-related pain while reducing the medication burden for patients with cancer, according to a study published in BMJ Supportive & Palliative Care.
“It’s very important to first examine the role of conventional approaches [to cancer-related pain] because, in my experience, medical cannabis is not an alternative treatment,” researcher Antonio Vigano, MD, MSc, associate professor in the departments of oncology and medicine at McGill University and director of McGill Nutrition and Performance Laboratory, told Healio. “It has to be a complementary treatment. That means it’s a way of filling the gaps in care that conventional treatment can’t achieve.”
In the Canadian study of 358 adults with cancer, Vigano and colleagues found that strains of medical cannabis with balanced proportions of THC and CBD conferred better pain relief than strains dominant in either THC or CBD. They also found an association of medical cannabis use with a reduction in overall medication burden and a decrease in opioid use.
Vigano spoke with Healio about the study findings and what they might mean for the future of medical cannabis for cancer-related pain.
Healio: What inspired you to conduct this study?
Vigano: One aspect of care that is very important for patients with cancer is optimal symptom control, which we are fairly good at achieving except with some patients who present with a very complex pain syndrome or with symptoms that are difficult to treat through conventional approaches. For example, medical cannabis helps people with appetite stimulation. The medications that normally stimulate appetite do so as a side effect or at the expense of side effects, as is the case with corticosteroids, for instance.
So, medical cannabis initially interested me because I was looking at a problem with cancer cachexia. From there, I also realized the possibility of using medical marijuana to help with insomnia and/or pain control, because most of the patients I treat with medical cannabis didn’t achieve adequate pain control with conventional medication, or the conventional medications caused too many side effects.
Medical cannabis needs to be used as part of a very personalized approach. The patient needs to be evaluated in terms of indications, contraindications and precautions, as we would do with any other medication. However, with medical cannabis, we don’t have a standardized dose. We know that beyond a certain amount of either THC or CBD, we probably don’t achieve more benefit. Over the past 5 years, we have organized a medical cannabis program where patients receive a specific recommendation for treatment and are monitored over time.
Healio: How did you conduct the study?
Vigano: We evaluated data collected from patients with cancer enrolled in the Quebec Cannabis Registry. We assessed Brief Pain Inventory, revised Edmonton Symptom Assessment System (ESAS-r) questionnaires, total medication burden and morphine equivalent daily dose at 3-month, 6-month and 12-month follow-up, and compared these measurements to baseline values. We also documented adverse events at each follow-up visit.
Healio: What did you find?
Vigano: One key finding pertained to the safety of the medical cannabis. We didn’t have any serious adverse events, only mild events that did not prevent the continuation of the medical cannabis treatment. The most common were sleepiness and fatigue.
The second key finding was that we demonstrated both statistically significant and clinically significant improvement in pain reports as measured by the Brief Pain Inventory.
In the past, we saw no statistically significant differences in pain intensity. However, most of the studies that have been published found that the difference between giving cannabis vs. placebo was not very relevant.
What we observed in our practice, which is also reflected in this study, is that the main effect or positive effect of medical cannabis was on pain interference. Patients can do their activities — they can enjoy their lives and sleep at night. So, that has been our main result — a statistically and clinically significant reduction by about 30% in pain interference among patients using cannabis.
Another important finding was a decrease at all follow-ups in the total medication burden (TMB) for these patients.
Healio: Does this include opioid medications?
Vigano: We calculated opioids in a different type of analysis. First we evaluated medication burden, which included medications such as antianxiety, antidepressants and others frequently used by patients with cancer. Then we did an analysis of opioids specifically. We used a medication quantification system, which is meant not just to measure the quantity of medications used, but also the specific weight these medications have in relation to possible adverse effects.
Different types of opioids have different strengths: 1 µg of morphine is not equal to 1 µg of hydromorphone; 1 µg of hydromorphone is five times more potent than 1 µg of morphine. So, to quantify opioids, we need to convert all these opioids to a standard common quantification, morphine equivalent daily dose (MEDD), which is the equivalent of morphine taken orally over 24 hours.
We demonstrated a decrease in MEDD over the first three follow-up assessments. This is initial evidence. The fact that we could report improvements in those outcomes was important for us.
Healio: What do you expect to be the long-term implications of this study?
Vigano: There is a lot of disagreement in Great Britain about whether to have medical cannabis not only more available, but also paid for by the National Health Service. This remains an issue in Canada, too, although in Canada we have a very regulated but still practical approach to medical cannabis. Medical cannabis is not reimbursed by the provincial or federal programs as another medication. Only a few private insurances support medical cannabis.
However, I think this study reflects the perspective of many patients who have benefited from medical cannabis. My sense is that the way to make it more successful would to be adequately train health professionals to monitor patients who use medical cannabis and to know when there is truly a proper place for medical cannabis. We receive many referrals to our medical cannabis program, but sometimes these patients have not yet been treated with commonly available medications.
We also have to remember, for instance, that you cannot cross a border carrying medical cannabis. So, at times, these patients need to stop the medical cannabis before they leave Canada. I try to take advantage of this challenge, because when these patients go off medical cannabis for a while, they regain sensitivity to it. So, we may overcome the tolerance that these patients develop over time.
However, the reality is that without appropriate training, these patients are not well served. If they need to stop medical cannabis, they might go through withdrawal symptoms that could have been prevented.
Medical cannabis is an important therapeutic tool and we should familiarize ourselves with it. Of course, it is part of a category of complementary treatments that range from medical cannabis to psychedelics. In my opinion, it’s all about putting these tools in the hands of health professionals and ensuring that they are regulated, as is the case with any other medical product.
For more information:
Antonio Vigano, MD, MSc, can be reached at McGill University, 5252 Boulevard de Maisonneuve West, Suite 105-B, Montreal, Quebec H4A 3S5, Canada; email: antonio.vigano@mcgill.ca .
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