Perspective from Marisa C. Weiss, MD
Disclosures: Nugent reports no relevant financial disclosures.
April 15, 2020
5 min read

‘Sound evidence base’ needed amid growing acceptance of cannabis for patients with cancer

Perspective from Marisa C. Weiss, MD
Disclosures: Nugent reports no relevant financial disclosures.
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Shannon Nugent, PhD
Shannon Nugent

Medical cannabis is now legal in 33 states, most of which consider cancer a qualifying condition for its use in symptom palliation.

With the legalization of medical cannabis has come increased acceptance of its use among patients, clinicians and the general public.

Nearly a quarter of patients with cancer report current cannabis use, and 90% of cancer survivors view cannabis as potentially beneficial for managing symptoms and support its legalization, according to data cited by Shannon Nugent, PhD, assistant professor in the department of psychiatry at Oregon Health & Science University, and colleagues in a commentary published in Cancer.

Clinicians have begun to incorporate medical cannabis into their cancer care regimens. According to Nugent and colleagues, studies have shown that about 80% of oncologists reported discussing medical cannabis with their patients, with 46% recommending its use, the commentary states. However, approximately 70% of these oncologists reported being inadequately educated about the use of medical cannabis.

“I don’t think physician education has been able to keep up with the rapidly changing social and policy landscape and increased use of cannabis,” Nugent told Healio. “There appears to be a disconnect between the legal status of medical cannabis, high acceptance of cannabis by patients, moderate acceptance of cannabis by clinicians, and the limited evidence base about its safety and efficacy.”

Nugent spoke with Healio about a recent study that showed cannabis to be ineffective for managing cancer-associated pain, as well as concerns about the safety of cannabis use among patients with cancer and the need for further research.

Question: Is the increased use of medical cannabis driven mostly by its legalization?

Answer: Data suggest that public acceptance of medical cannabis and use among individuals with cancer are increasing. We hypothesized that these factors may be contributing to more use among those with cancer — and that many of these decisions are taking place outside the context of medical consultation — but we don’t think we know that with certainty.

Q: Do you think current evidence on medical cannabis is adequate to warrant its widespread use?

A: As we noted in our commentary, the high acceptance of medical cannabis among patients and clinicians does not seem to be supported by the evidence. Approximately 75% of individuals with cancer who use cannabis use it for symptom management, most commonly pain, nausea and sleep disruption. However, the evidence base supporting benefit for most of these symptoms is insufficient. Several recent systematic reviews have found no benefit for pain. There is some evidence for the antiemetic properties of pharmaceutically prepared synthetic cannabis — nabilone or dronabinol.


Q: What are some of the health and safety concerns regarding medical cannabis use?

A: There are many potential adverse events, including potential drug-drug interactions with cancer therapies. In addition, cannabis use is associated with other acute medical, mental health and safety risks, including increased risk for motor vehicle accidents, manic episodes and psychosis, as well as small negative effects on cognitive functioning among frequent users. Finally, although there is a body of in vivo and in vitro laboratory evidence to suggest possible mechanisms for the antitumor properties of cannabis, such as induction of apoptosis and prevention of tumor cell proliferation, these findings have not been translated to humans. We assert that endorsement of medical cannabis for purported anti-neoplastic properties or in lieu of FDA-approved cancer treatments is potentially dangerous.

Q: Do you think studies that show questionable or unfavorable results with cannabis among patients with cancer will or should have an impact on its future use?

A: Yes, this information should be disseminated to clinicians and to the public so they can have informed discussions and make informed decisions. There are several initiatives to disseminate what we currently know, in order to close this educational gap. However, more information, as well as a sound evidence base from which to educate, is needed. – by Jennifer Byrne


Nugent S, et al. Cancer. 2019;doi:10.1002/cncr.32732.

For more information:

Shannon Nugent, PhD, can be reached at Oregon Health & Science University, 3181 S.W. Sam Jackson Park Road, Portland, OR 97239-3098.

Disclosure: Nugent reports no relevant financial disclosures.