A Coala-T-Cannabis Survey Study of breast cancer patients' use of cannabis before, during, and after treatment

Cancer. 2022 Jan 1;128(1):160-168. doi: 10.1002/cncr.33906. Epub 2021 Oct 12.


Background: The goal of this study was to characterize cannabis use among patients with breast cancer, including their reasons for and timing of use, their sources of cannabis information and products, their satisfaction with the information found, their perceptions of its safety, and their dialogue about cannabis with their physicians.

Methods: United States-based members of the Breastcancer.org and Healthline.com communities with a self-reported diagnosis of breast cancer within 5 years (age ≥ 18 years) were invited to participate in an anonymous online survey. After informed consent was obtained, nonidentifiable data were collected and analyzed.

Results: Of all participants (n = 612), 42% (n = 257) reported using cannabis for relief of symptoms, which included pain (78%), insomnia (70%), anxiety (57%), stress (51%), and nausea/vomiting (46%). Furthermore, 49% of cannabis users believed that medical cannabis could be used to treat cancer itself. Of those taking cannabis, 79% had used it during treatment, which included systemic therapies, radiation, and surgery. At the same time, few (39%) had discussed it with any of their physicians.

Conclusions: A significant percentage of survey participants (42%) used cannabis to address symptoms; approximately half of these participants believed that cannabis could treat cancer itself. Most participants used cannabis during active cancer treatment despite the potential for an adverse event during this vulnerable time. Furthermore, most participants believed that cannabis was safe and were unaware that product quality varied widely and depended on the source. This study reviews the research on medicinal cannabis in the setting of these findings to help physicians to recognize its risks and benefits for patients with cancer.

Lay summary: Almost half of patients with breast cancer use cannabis, most commonly during active treatment to manage common symptoms and side effects: pain, anxiety, insomnia, and nausea. However, most patients do not discuss cannabis use with their physicians. Instead, the internet and family/friends are the most common sources of cannabis information. Furthermore, most participants believe that cannabis products are safe and are unaware that the safety of many products is untested.

Keywords: breast cancer; cannabis; marijuana; palliation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Breast Neoplasms* / drug therapy
  • Breast Neoplasms* / epidemiology
  • Cannabis*
  • Female
  • Humans
  • Medical Marijuana* / adverse effects
  • Medical Marijuana* / therapeutic use
  • Nausea / chemically induced
  • Nausea / epidemiology
  • Surveys and Questionnaires


  • Medical Marijuana