Nearly half of people in treatment for breast cancer use cannabis to alleviate common therapy-related problems, such as pain, anxiety, insomnia and nausea, but many do not discuss this usage with their doctor, according to an article in U.S. News and World Report about new study findings published in the journal Cancer.

Cannabis, or marijuana, is the product of a family of plants that also produces hemp. For centuries, many groups of people have used cannabis medicinally. But the herbal remedy, which is legally available in many states for specific illnesses, has not been approved by the Food and Drug Administration to treat cancer patients.

For the study, researchers invited 612 adult members of the and communities to complete a 47-question anonymous online survey. All participants—605 women, five men and two people who did not indicate their gender—reported having a breast cancer diagnosis within the previous five years. Individuals participated in the study from December 2016 to January 19, 2020.

Breast cancer patients were asked why and when they used marijuana, their source of information about it, how they felt about the plant’s safety and whether they spoke to their doctors about their marijuana use. Forty-two percent reported using cannabis for symptom relief. For these cannabis users, pain was the reason most cited (78%), followed by insomnia (70%), anxiety (57%), stress (51%) and nausea or vomiting (46%).

“They are not using it to get high but to manage the side effects of breast cancer or the treatments for breast cancer,” Marisa Weiss, MD, an oncologist at Lankenau Medical Center in Wynnewood, Pennsylvania who cofounded and was one of the study’s authors, told

But symptom relief wasn’t the only motivation. Nearly half of the participants (49%) who used marijuana believed the medical version of the plant could treat their cancer. Most of them (79%) added it to their systematic therapies, radiation treatment and surgery. Yet only 39% discussed their use with their doctors.

The survey results also showed that most respondents were unaware that marijuana quality varied and thought all marijuana products were safe. Most respondents also used pot during active cancer treatment even though there was a possibility of harm.

“Some chemotherapy drugs are broken down by the same part of the liver that cannabis is, and you don’t want to overtax the liver,” Weiss told U.S. News & World Report. And, she added, “smoking or vaping when receiving radiation or other therapies to your chest could affect lung function.”

The survey authors conclude: “Providers should communicate clearly about the health and safety concerns associated with certain cannabis products and methods of delivery. 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.”

To learn more about breast cancer, read “Community: My Life With Metastatic Breast Cancer.” To learn about safe cannabis use, see “How to Use Cannabis.”