David Casarett MD

 

The problem:  People with cancer face numerous symptoms, including pain, nausea, loss of appetite, insomnia, and anxiety.   These symptoms can be debilitating, and are often difficult to treat, so there’s a lot of enthusiasm for understanding how cannabis could be helpful.

 

Why do this study?   There haven’t been many studies of cannabis to relieve cancer symptoms.  The few studies that have been done have generally been small randomized controlled trials focused on one symptom.  So it would be useful to know how well cannabis works across multiple symptoms, in a large population of patients with difference cancer diagnoses.  We also don’t know how well patients with cancer can tolerate cannabis.  Cannabis is generally very safe.  However, some side effects like dizziness or confusion—that aren’t bothersome for a healthy 20-year-old—may be disturbing or even dangerous to a patient with advanced cancer who is weak, frail, or unsteady. 

 

The study:  At the start of the study, 3619 patients got a medical cannabis license. Patients in this study mostly had breast, lung, pancreatic or colorectal cancer, although many other cancer types were included as well.  A total of 2,923 people filled out a baseline survey.  Of these, 2,082 and 1,248 completed additional surveys at one and six months, respectively. Between surveys, a total of about 20% of people stopped using cannabis (either because of side effects or because their symptoms had improved) and about a third died.  Of those patients who were still using cannabis at each time point, survey response rates were about 2/3.  That response rate is good for a survey of this type and it means that the people who completed the survey are probably similar to the entire population.  Key results:

• One month after starting cannabis, two thirds of patients said that their symptoms were significantly improved.

• At 6 months, 51% of those still in the study said they’d had significant improvement. 

• The most improved symptoms were nausea/vomiting (91%), sleep (84%), and restlessness 88%).

• There was a very large decrease in the proportion of patients with severe pain, from 53% to 5%. (The authors used a well-accepted definition of ‘severe’ pain as being at least an 8 on a 0-10 scale).

• Of the patients taking opioids at the start of the study, 1/3 stopped them while using cannabis.

• After one month of cannabis use, only 6% reported side effects.  However, at 6 months, about 30% reported side effects.

 

Conclusions:  This study found that patients with cancer report large benefits of cannabis for multiple symptoms, and many were able to stop taking opioids.  Rates of side effects were generally low, although they seemed to increase over time.

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What does this study add?  The reported benefits are impressive, and the reported risks are small, which is good news for patients struggling with symptoms due to cancer.  This study also provides evidence that even seriously ill patients with cancer—some of whom are very close to the end of life—believe that cannabis is effective and safe.

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Funder:  This study was funded by Tikun-Olam, a grower/producer of medical cannabis in Israel.

 

Author conflicts:  Five of 8 authors receive compensation from Tikun-Olam.

 

Commentary: 

This is a nice study of seriously ill cancer patients.  These studies can be difficult to do, because recruiting patients can be difficult and keeping patients in the study can be even harder.  When people feel bad, they don’t want to spend time filling out surveys.  But this is the population of patients I take care of every day, and I know that we need new and better treatments to manage symptoms and improve quality of life.  So I commend the authors on their efforts. 

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This is a “real world” study, with all of the advantages and disadvantages that come with that type of research.  So about 20% of people who started the surveys stopped treatment. Why does that matter?  It matters if those 20% are dropping out because they didn’t think cannabis was helping them.  If you lose the patients for whom cannabis isn’t working, then most of the patients left in the study are going to say that cannabis is effective.  That is, you’re going to end up with a survey showing higher ratings of effectiveness than is really the case.  This probably is a minor concern, because patient dropouts were uncommon, and so any effect on the results is likely to be small.

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Also, the decrease in patients reporting severe pain is impressive, as is the proportion of patients who stopped taking opioids.  Maybe it’s too impressive.  Was all of that improvement due to cannabis?  Probably not.  These patients were undergoing treatments like chemotherapy and radiation therapy, and some had surgery for their cancers.  Those interventions, plus other medications and treatments, probably also played a role in reducing these patients’ symptoms.  How much, though, is a really interesting question.  Did cannabis add a little?  Or a lot?  Or does the answer depend on other factors, like what kind of cancer patients had, and what symptom they were treating?

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But this is still a very useful study.  It shows that most people using cannabis perceive that it’s beneficial for them.  Also, that they tolerate it well.  Just the fact that these patients—most of whom are very sick—can use cannabis without serious side effects, is very useful.  This study doesn’t ‘prove’ that cannabis is effective for these symptoms.  For that we’d need lots of randomized controlled trials.  But for patients who are considering cannabis, and for their physicians who aren’t sure whether to recommend it, this study should offer some reassurance that cannabis could be a good choice, and that it’s probably a safe one.