You may read reports that cannabis (marijuana) is good for treating cancer and its symptoms.

As we say in our Cannabis and Cannabinoids (Marijuana) review, there is currently not enough evidence that cannabis is effective in treating cancer itself, though it appears to help with relieving a number of symptoms such as nausea and pain.

A new study has found that, at least in the case of human papilloma virus (HPV)-positive head and neck cancer, smoking cannabis daily may have cancer-promoting effects.1Liu C, Sadat SH et al. Cannabinoids promote progression of HPV positive head and neck squamous cell carcinoma via p38 MAPK activation. Clinical Cancer Research. 2020.

Large studies indicate that smoking cannabis on a daily basis is linked to a higher risk of HPV-positive head and neck cancer and worse outcomes for those with this diagnosis.2Zhang ZF, Morgenstern H et al. Marijuana use and increased risk of squamous cell carcinoma of the head and neck. Cancer Epidemiology, Biomarkers & Prevention. 1999;8(12):1071–1078; Gillison ML, D’Souza G et al. Distinct risk factor profiles for human papillomavirus type 16-positive and human papillomavirus type 16-negative head and neck cancers. Journal of the National Cancer Institute. 2008;100(6):407–420; Sonawane K, Suk R, Chiao EY, et al. Differences in prevalence between sexes and concordance with genital human papillomavirus infection, NHANES 2011 to 2014. Annals of Internal Medicine. 2017;167(10):714–724; Xie M, Gupta MK et al. Marijuana and head and neck cancer: an epidemiological review. Journal of Otolaryngology—Head & Neck Surgery. 2018;47(1):73. According to the current study’s authors, this increased risk hasn’t shown up in HPV-negative head and neck cancer.

The researchers went on to do a study using cells, animals and then humans with HPV-positive head and neck cancer to find a biological explanation of the connection between cannabinoids and this cancer. Using doses of cannabinoids typical of recreational cannabis use, they found that cannabinoids activate a biological pathway known to promote cancer cell growth and spread, as well as inhibit cell death (apoptosis).

What does this mean in the real world? The authors point out that HPV-positive head and neck cancer is on the rise, with a number of things going on to drive that: a slump in number of people getting the HPV vaccine, rising genital HPV infections (often called genital warts) being transferred to the mouth and throat through oral sex, and rising recreational use of cannabis as more states legalize it. These three factors are all behaviors that people can change. 

If you have HPV-positive head and neck cancer, it would make sense to stop using cannabis. Since the study only looked at typical daily recreational use, we don’t know if there is a “safe” dose of cannabis that wouldn’t activate the pro-cancer pathway. The study didn’t identify which cannabinoids (THC, CBD, etc) are activating the pathway. If your doctor has prescribed medical cannabis for a health condition, discuss your options with your doctor.

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About the Author

Laura Pole, RN, MSN, OCNS

Laura Pole is senior clinical consultant for CancerChoices. Laura is an oncology clinical nurse specialist who has been providing integrative oncology clinical care, navigation, consultation, and education services for over 40 years.

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Laura Pole is senior clinical consultant for CancerChoices. Laura is an oncology clinical nurse specialist who has been providing integrative oncology clinical care, navigation, consultation, and education services for over 40 years. She is the co-creator and co-coordinator of the Integrative Oncology Navigation Training at Smith Center for Healing and the Arts in Washington, DC. Laura also manages the “Media Watch Cancer News That You Can Use” listserv for Smith Center/Commonweal. In her role as a palliative care educator and consultant, Laura has served as statewide Respecting Choices Faculty for the Virginia POST (Physician Orders for Scope of Treatment) Collaborative as well as provided statewide professional education on palliative and end-of-life care for the Virginia Association for Hospices and Palliative Care.

For CancerChoices, Laura curates content and research, networks with clinical and organizational partners, brings awareness and education of integrative oncology at professional and patient conferences and programs, and translates research into information relevant to the patient experience as well as clinical practice.

Laura sees her work with CancerChoices as a perfect alignment of all her passions, knowledge and skills in integrative oncology care. She is honored to serve you.

Laura Pole, RN, MSN, OCNS Senior Clinical Consultant