In an effort to ease the discomfort associated with breast cancer treatment, many patients are using marijuana — and most aren’t telling their doctors. That’s according to a study published earlier this month in the peer-reviewed journal of the American Cancer Society, Cancer.

The report saw individuals who were members of online health communities on breastcancer.org and Healthline take part in an anonymous survey. It analyzed cannabis use among adults who were diagnosed with breast cancer, which is common in women 65 and older.

Findings showed that 42% of 612 adult breast cancer patients said they used a form of cannabis for symptom relief. Those symptoms included nausea and vomiting, pain, insomnia, anxiety and stress. The majority, 75%, reported that it was extremely or very helpful with providing relief. Of those using cannabis, 79% used it during treatment including systemic therapies, radiation and surgery.

Half the participants sought information on medical cannabis. Websites and other patients were reported to be the most helpful sources, while physicians ranked low. Most of those who looked for information on medical marijuana were dissatisfied with the information they obtained. Most people also considered the products safe, unaware that many products’ safety is untested.

“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,” lead author Dr. Marisa Weiss, of breastcancer.org and Pennsylvania’s Lankenau Medical Center, said in a press release.

“Not knowing whether or not our cancer patients are using cannabis is a major blind spot in our ability to provide optimal care, and as healthcare providers, we need to do a better job of initiating informed conversations about medical cannabis with our patients to make sure their symptoms and side effects are being adequately managed while minimizing the risk of potential adverse effects, treatment interactions, or non-adherence to standard treatments due to misinformation about the use of medical cannabis to treat cancer,” she added.

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