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Many breast cancer patients are using marijuana and not telling their doctors

Many use cannabis products as pain relief and to ease the side effects of breast cancer treatment, new research finds.
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Many breast cancer patients use cannabis to ease the symptoms of the disease and its treatments, but few tell their doctors, a new survey finds.

In an online anonymous survey of more than 600 adults with a breast cancer diagnosis, 42 percent reported using some form of cannabis for relief of symptoms such as nausea and vomiting, pain, insomnia, anxiety and stress, according to the report published Tuesday in Cancer.

“They are not using it to get high, but to manage the side effects of breast cancer or the treatments for breast cancer,” said the study’s author, Dr. Marisa Weiss, founder and chief medical officer of and an oncologist at the Lankenau Medical Center in Wynnewood, Pennsylvania. “It can be a pretty rough ride. People are struggling to keep going and to have a reasonable quality of life.”

To take a closer look at breast cancer patients’ use of cannabis, Weiss and her colleagues sent a 47-question survey to 612 adults — 605 were women and five were men. The other two preferred not to answer the question about gender. All were recruited via and’s community.

While 39 percent said they had mentioned cannabis to their doctors, just 4 percent of the 306 participants who said they wanted more information had turned to their physicians for information on the drug. Most sought information from other sources, including websites or cannabis dispensary staff. Eighteen percent turned to a family member or friend. Most said they were unsatisfied with the information they received.

Out of the 42 percent who said they were using cannabis, 78 percent said they were using it for pain relief, 70 percent to help with insomnia, 57 percent to relieve anxiety, 51 percent to deal with stress, and 46 percent to stem nausea and vomiting. Most, 79 percent, said they used cannabis during treatment.

The respondents reported using multiple sources of cannabis: Seventy percent said they used edibles, and 65 percent liquids or tinctures. Just over half said they smoked and almost half used vape pens. They also reported using three to four different products, on average

“Few are telling their doctors about it,” said Weiss, “and many are getting information, as well as products, from family members.”

The majority of the participants, 70 percent, believed that cannabis should be viewed as a plant-based medicine, that natural products are better than “chemicals” and that the benefits of cannabis outweighed the risks. Moreover, 49 percent of the cannabis users said they believed that medical cannabis could be used to treat the cancer itself.

While acknowledging that cannabis can bring relief to breast cancer patients, Weiss is concerned that patients aren’t consulting with their doctors.

“Some of these products can interact with treatments they are taking, and there is a safety issue there,” she said. “We want to make sure they get relief from their symptoms without interfering with the treatments.”

One concern, Weiss said, is that the liver is involved in the metabolism of many of the treatments as well as of cannabis. “We don’t want to overtax the liver,” she said.

It’s also not currently known how cannabis interacts with treatments, she added.

The new study is “very interesting,” said Dr. Stephanie Bernik, chief of breast surgery at Mount Sinai West in New York. “Our patients have been using marijuana for cancer for years and years,” she added. “So we knew it helps with symptoms.”

The new report shows that “not a lot of patients are talking to their doctors about this,” Bernik said. And that means that the doctors can’t take cannabis into account when they are deciding dosages of cancer drugs, she added.

“It may alter the metabolism of these medications when getting the chemotherapy dosing is really important,” Bernik said.

More research is needed on cannabis use during cancer treatments to figure out interactions and dosing, Bernik said.

“It also points to the importance of patients being open with their doctors," said Bernik. "And doctors need to specifically ask about it. They probably need to start the conversation.”

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