Almost half of US adults with breast cancer use cannabis to manage their symptoms and side effects according to an anonymous online poll — but most don’t tell their doctor.

Published by Wiley in Cancer, a peer-reviewed journal of the American Cancer Society, researchers examined cannabis use among adults diagnosed with breast cancer within five years who were members of the Breastcancer.org and Healthline.com online health communities.

They found 42% of the 612 participants reported using cannabis for relief of symptoms including pain, insomnia, anxiety, stress, and nausea/vomiting. 

Dr Marisa Weiss

Among those who used cannabis, 75% said it was extremely or very helpful at relieving their symptoms; 79% had used it during treatment, including systemic therapies, radiation, and surgery; and nearly half (49%) believed medicinal cannabis could be used to treat cancer itself, despite the lack of evidence for its efficacy.

Half of participants sought information on medicinal cannabis, with websites and other patients considered the most helpful sources. However, physicians ranked low on the list, with most of those asking their doctor for guidance unsatisfied with the information they received.

Most participants believed cannabis products to be safe and were unaware that many are untested for safety in the US. They reported using a wide range of products known to vary in quality and purity.

Lead author Dr Marisa Weiss said: “Our study highlights an important opportunity for providers to initiate informed conversations about medical cannabis with their patients, as the evidence shows many are using [it] without our knowledge or guidance.”

“Not knowing whether or not our cancer patients are using cannabis is a major blind spot in our ability to provide optimal care. 

“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 minimising 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.”

Dr Weiss stressed patients should never use cannabis as an alternative to standard cancer treatment, and that clinicians should inform patients about the safe and effective use of cannabis as an adjunct to their treatment plan.

Prior to launching Cannabiz, Martin was co-founder and CEO of Asia-Pac’s leading B2B media and marketing information brand Mumbrella, overseeing its sale to Diversified Communications in 2017. A journalist...