Many Breast Cancer Patients Use Cannabis for Symptom Relief

Roxanne Nelson, RN, BSN

October 21, 2021

A new survey of US patients with breast cancer found that 42% were using cannabis, primarily to relieve side effects associated with treatment, such as pain, anxiety, nausea, and insomnia.

Most (75%) of the patients who reported using cannabis said it was extremely helpful or very helpful in alleviating symptoms.

The authors warn of potential safety concerns with cannabis, especially with the use of unregulated products.

In addition, the survey found that physicians were not highly regarded as a source of information about cannabis use. Only 39% of patients said that they discussed cannabis with their physicians; 28% reported feeling uncomfortable when broaching the topic. Only 4% indicated that physicians were the most helpful source of information about cannabis.

The survey involved 612 patients with breast cancer. The results were published online October 12 in Cancer.

"Our study highlights an important opportunity for providers to initiate informed conversations about medical cannabis with their patients, as the evidence shows that many are using medical cannabis without our knowledge or guidance," said lead author Marisa Weiss, MD, of and the Lankenau Medical Center, near Philadelphia, Pennsylvania. "Not knowing whether or not our cancer patients are using cannabis is a major blind spot in our ability to provide optimal care," she said.

Cannabis in one form or another has been legalized in many states across America, and even in states where it hasn't been legalized, people are using it.

"Even though many states have relaxed their laws on cannabis, it remains a Schedule I drug on the federal level and is essentially still considered illegal," commented Donald I. Abrams, MD, professor of medicine at the University of California, San Francisco, and an integrative oncologist at the UCSF Osher Center for Integrative Medicine. "This is why many physicians are uncomfortable discussing it with patients," he said.

"Cannabis use isn't taught in medical school, and until that changes, I don't know how physicians are going to be advisers for this," said Abrams, who was approached by Medscape Medical News for comment.

This "is a really nice study in that it looks at a large group of breast cancer patients from the community.... It's not from a single institution [such as this previous study] and so a more representative mix," Adams said.

However, Abrams also commented that the article had a "scent of 'reefer madness' " about it, given its emphasis on potential harms and safety concerns.

"It's interesting how alcohol is considered mainstream but cannabis has been demonized," he said. "Especially for women with breast cancer, it's so clear that alcohol is related to the development of postmenopausal breast cancer. As a recreational intervention, cannabis in my mind appears to be much safer for women for relaxation.

"The one thing I worry about are patients who take highly concentrated CBD [cannabidiol] oil, as it can block the metabolism of prescription drugs and allow them to build up in the blood," Abrams said. "I advise people against using these products."

Cannabis to Relieve Symptoms

Previous studies have noted widespread use of cannabis among patients with cancer. For example, a large study from Israel that included nearly 3000 participants found that cannabis use improved a variety of cancer-related symptoms, including nausea and vomiting, sleep disorders, pain, anxiety, and depression. Among those with cancer who survived to 6 months and who finished the study protocol, 60% achieved "treatment success." Of note, at 6 months, 36% of patients had stopped taking opioids, and for 9.9%, the dose of opioids had decreased.

In the current study, dubbed the Coala-T-Cannabis study, the investigators approached US members of the and communities who self-reported that they had been diagnosed with breast cancer within the past 5 years; 612 surveys were completed.

Half of all respondents said they had looked for information on medical cannabis, but most were unsatisfied with the information that they had received. Only 6% were extremely satisfied; 25% were very satisfied with the information.

Most patients (39%) did not discuss cannabis use with their physicians. Of those who did, 28% reported feeling uncomfortable discussing the topic. Only 4% of survey respondents indicated that physicians were the most helpful source of cannabis information.

Regarding which source of information was most helpful, 22% said websites, 18% said family members or friends, 12% said staffers and pharmacists in dispensaries, and 7% said other patients with breast cancer.

Forty-two percent of the survey respondents said they used cannabis for medical purposes and for relief of symptoms, which included pain (78%), insomnia (70%), anxiety (57%), stress (51%), and nausea/vomiting (46%).

In addition, 49% believed that medical cannabis could be used to treat the cancer itself.

A fair number were also using cannabis for recreational purposes. Of those who used cannabis, only 23% reported that they used it for medical purposes only.

Participants used cannabis in a variety of forms. The most popular form of consumption was as edibles (70%), followed by liquids/tinctures (65%), smoking (51%), topicals (46%), and vape pens (45%). Participants reported using an average of 3.7 different products.

Safety Concerns?

The authors caution about the use of cannabis while receiving anticancer therapies, because such use "raises important efficacy and safety concerns.

"Many chemotherapy agents as well as cannabinoids are metabolized in the liver's p450 cytochrome system," Weiss and colleagues note, and the mechanism by which cannabinoids interact with particular CYP450 isoenzymes "has the potential to alter the metabolism of other medications and lead to adverse side effects."

They also question the safety of some of the cannabis products that are being used. Participants reported receiving cannabis from a variety of sources, which included state-regulated dispensaries, "dealers," and family/friends.

Three quarters of respondents believed that cannabis was better than "chemicals" and that the benefits outweighed the risks. But many of the products used are unregulated, the authors point out.

"Providers should communicate clearly about the health and safety concerns associated with certain cannabis products and methods of delivery," they conclude. "Without these measures, patients may make these decisions without qualified medical guidance, obtain poor-quality cannabis products, and consume them through potentially hazardous delivery methods during various types of cancer therapies."

The study was supported by research grants from Ananda Health/Ecofibre and the Dr Philip Reeves Legacy Fund. Several co-authors reported relationships with industry, as noted in the article. Abrams owns stock in Cannformatics and Lumen; he has received honorarium from Clever Leaves and Maui Grown Therapies, and speaker honorarium from GW Pharmaceuticals.

Cancer. Published online October 12, 2012. Full text

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