30 Apr UCSD Study Finds Heavy Cannabis Use Associated With Worse Survival from Colon Cancer

MedicalResearch.com Interview with:

Dr. Cuomo

Raphael E. Cuomo, PhD, MPH, CPH, FRSPH
Professor, School of Medicine
University of California, San Diego

MedicalResearch.com: What is the background for this study?

Response: Colon cancer remains a leading cause of cancer-related death worldwide. Recent years have seen a substantial increase in cannabis use, but limited research has explored its potential influence on cancer outcomes. We conducted a large-scale retrospective cohort study using real-world clinical data to investigate whether a diagnosis of cannabis use disorder prior to colon cancer diagnosis was associated with survival outcomes.

MedicalResearch.com: What are the main findings?

Response:  Our main finding was that patients with a history of cannabis use disorder had a markedly higher risk of dying within five years of their colon cancer diagnosis compared to those without cannabis use disorder, even after adjusting for demographic and clinical factors.

MedicalResearch.com: Were the heavy users less sensitive to possible colon cancer symptoms? Less likely to pursue checkups?

Prior research suggests that individuals with substance use disorders, including for cannabis, may delay medical attention for early symptoms and face greater barriers to preventive care. However, our study did not directly measure symptom sensitivity or healthcare-seeking behavior. This pattern could partly why we observed a higher rate of poor outcomes in the group with cannabis use disorder. More detailed studies are needed to disentangle behavioral factors from biological mechanisms in this context.

MedicalResearch.com: What should readers take away from your report?

Response: The key takeaway is that heavy cannabis use—particularly patterns severe enough to result in a clinical diagnosis of cannabis use disorder—may negatively impact cancer survival. Patients, clinicians, and policymakers should be aware that cannabis is not a benign substance for all individuals, especially when used heavily or chronically. Discussions around cannabis use should be grounded in scientific evidence, not assumptions. 

MedicalResearch.com: What recommendations do you have for future research as a results of this study?

Response: Future research should explore the biological pathways through which cannabis might influence cancer progression, such as effects on the immune system or tumor microenvironment. Additionally, prospective studies are needed to assess how cannabis use patterns before and after a cancer diagnosis affect long-term outcomes. Understanding these dynamics is critical as cannabis use becomes more widespread globally.

MedicalResearch.com: Is there anything else you would like to add? Any disclosures?

Response: This study underscores the importance of considering substance use history as part of comprehensive cancer care. While cannabis may hold therapeutic promise for some symptoms, chronic heavy use could carry risks that should not be overlooked.

Disclosures: I have no financial conflicts of interest related to this study.

Citation:

Raphael E. Cuomo,
Cannabis use disorder and mortality among patients with colon cancer,
Annals of Epidemiology,
Volume 106, 2025, Pages 8-10, ISSN 1047-2797,
https://doi.org/10.1016/j.annepidem.2025.04.012

For substance abuse treatment and mental health referrals,
 Contact the Substance Abuse and Mental Health Services Administration’s (SAMHSA) National Helpline
1-800-662-HELP (4357).

More information:

• Chao Liu, Sayed H. Sadat, Koji Ebisumoto, Akihiro Sakai, Bharat A. Panuganti, Shuling Ren, Yusuke Goto, Sunny Haft, Takahito Fukusumi, Mizuo Ando, Yuki Saito, Theresa Guo, Pablo Tamayo, Huwate Yeerna, William Kim, Jacqueline Hubbard, Andrew B. Sharabi, J. Silvio Gutkind, Joseph A. Califano; Cannabinoids Promote Progression of HPV-Positive Head and Neck Squamous Cell Carcinoma via p38 MAPK Activation. Clin Cancer Res 1 June 2020; 26 (11): 2693–2703. https://doi.org/10.1158/1078-0432.CCR-18-3301

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Last Updated on April 30, 2025 by Marie Benz MD FAAD