In a groundbreaking study from the University of California San Diego School of Medicine, startling evidence has emerged connecting high cannabis use to significantly increased mortality rates in colon cancer patients. Researchers discovered that those with a documented history of heavy cannabis use were more than 20 times more likely to die within five years of their diagnosis than those who didn’t use cannabis.

Lead author Raphael Cuomo, Ph.D., an associate professor at UC San Diego and a member of the renowned Moore Cancer Center, emphasizes the implications of these findings: "This study contributes to a growing body of research indicating that strong cannabis usage may have often-overlooked effects on the immune system, mental health, and treatment behaviors—all critical factors that could ultimately affect cancer survival rates."

To reach these conclusions, researchers meticulously analyzed the electronic health records of over 1,000 colon cancer patients treated at the UC Health system from 2012 to 2024. They meticulously reviewed the cancer outcomes while controlling for vital factors such as age, sex, and disease severity through tumor staging and cancer biomarkers.

The analysis revealed shocking statistics: Patients with a cannabis use disorder (CUD) faced a jaw-dropping five-year mortality rate of 55.88%, in stark contrast to just 5.05% for those without such a disorder. In fact, patients diagnosed with CUD before their cancer diagnosis were found to be 24.4 times more likely to face death within five years.

Cuomo highlights the complexities of cannabis use, stating, "High cannabis use often correlates with mental health issues such as depression and anxiety, which can hinder a patient’s engagement with crucial cancer treatments. However, this isn’t an attack on cannabis; it’s a call to understand its full impact, particularly for those battling serious illnesses. We hope these findings spur more research and foster nuanced discussions about how cannabis interacts with cancer biology and care."