September 25, 2017
3 min read

One-quarter of patients with cancer report legal marijuana use

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One-quarter of patients with cancer in a state with legalized marijuana reported using the substance in the prior year, according to results of a cross-sectional, anonymous survey published in Cancer.

A majority of patients also desired information on marijuana use from their oncology providers.

“We were motivated to conduct this research by our patients,” Steven A. Pergam, MD, MPH, associate member of vaccine and infectious disease and clinical research divisions at Fred Hutchinson Cancer Center, associate professor in the division of allergy and infectious diseases at University of Washington, and medical director of infection control at Seattle Cancer Care Alliance, told HemOnc Today. “As an infectious diseases consultant, I felt that I was seeing and hearing more from patients about cannabis. At the same time, clinicians asked questions that they were getting from their patients about the safety of various forms of cannabis.”

Research has suggested that cannabis can help patients with cancer by alleviating anorexia, nausea and pain, as well as by improving mood and insomnia. Still, overall data on cannabis use in patients with cancer are limited, and some experts have raised safety concerns about use of the drug in immunosuppressed patients.

“In order to better protect our patients and to help provide guidance about cannabis use to our colleagues, we felt we needed to understand the frequency, methods and reasons our patients were using cannabis during their treatment,” Pergam said.

Marijuana is legal for recreational use in eight states and the District of Columbia, and medical marijuana is available in half of the U.S. states, increasing access among patients with cancer.

Pergam and colleagues conducted a survey among 926 patients (median age, 58 years; interquartile range [IQR], 44-66; 52% men) from Seattle Cancer Care Alliance to determine the prevalence and methods of use, the perceived benefits, and the sources of information about medical use. They used random urine samples for tetrahydrocannabinol for survey validation.

Sixty-six percent of respondents had used cannabis before, 24% had used cannabis in the last year and 21% reported use within the last week. Twenty-four percent of respondents reported regular use.

Among the active users, 74% reported using cannabis at least once a week, 56% reported daily use and 31% used cannabis multiple times daily. Active users reported smoking (70%), using edibles (70%) and dual use (40%).

Active users reported physical symptoms (75%) and neuropsychiatric symptoms (63%) as their main reasons for use.


“We expected patients would report using cannabis for nausea or as an appetite stimulant, as these symptoms are where cannabis is most frequently purported in the lay press and online forums to provide benefits,” Pergam said. “The frequency at which patients reported using cannabis for symptoms such as dealing with stress, coping with their illness and depression, was unexpected.

“Despite a lack of scientific evidence, more than a quarter of patients actually thought that cannabis was helping to treat their cancer,” Pergam added. “This indicates a need to better educate patients.”

Based on a scale from 1 to 10 — in which 1 indicates no change and 10 a great likelihood — active users reported being more likely to use cannabis because of its legalization (score, 8) than prior users (score, 4) and never users (score, 1; P < .001).

Most respondents wanted to learn more about cannabis and cancer (score, 6; IQR, 3-10), although this interest significantly varied by age (P < .01).

Seventy-four percent preferred to get information from their cancer team, but only 15% did so. Other sources of information included friends/family, newspaper/magazine articles, websites/blogs and another patient with cancer. More than one-third of patients received no information.

It is important for clinicians to ask their patients about cannabis use, Pergam said.

“As cancer providers, we need to show our willingness to talk about this with our patients because they want our opinions,” he said. “If we aren't open to these discussions, they will seek information from other sources. Clinicians should be honest that we don't know a lot about the risks and benefits of cannabis in cancer care. In those with very weakened immune systems, such as a bone marrow transplant patient, I am much more cautious and would actively discourage patient use.”

Evidence-based training and tools are needed to increase clinicians’ comfort discussing cannabis with their patients, Pergam added.

“Eventually, I hope to see more rigorous clinical trials aimed at addressing the potential risks and benefits of marijuana in cancer care,” he said. “The more data we have the better we will be able to educate and protect our patients.”– by Alexandra Todak

For more information:

Steven A. Pergam, MD, MPH, can be reached at Fred Hutchinson Cancer Research Center, 1100 Fairview Ave. North, E4-100, Seattle, WA 98109; email:

Disclosures: Pergam reports grant support from Merck and Optimer/Cubist Pharmaceuticals. One researcher reports consultant roles with Gilead Sciences and Quartet Health.