At The GrayVine, we know staying healthy means paying attention to the latest research, especially when it challenges what many consider harmless, or even beneficial, habits.

A new study from California is raising serious concerns about a growing daily ritual: regular cannabis use.

As laws evolve and cannabis becomes more mainstream, researchers are warning that this popular habit may have unexpected consequences.

A startling link between cannabis and colon cancer​

Colon cancer is one of the fastest-rising cancers in the US, particularly among young adults.


While tobacco and alcohol have long been known risk factors, cannabis use has often been left out of the conversation.

But new findings from the University of California San Diego are challenging assumptions.

The research, published in the Annals of Epidemiology, tracked more than 1,000 colon cancer patients and found a dramatic increase in mortality among near-daily cannabis users.

The numbers that should make you pause​

Daily cannabis users were 11 times more likely to die within five years of diagnosis than non-users.

For those with cannabis use disorder (CUD), a clinical diagnosis involving chronic, problematic use, the risk increased 24 times higher.


In the study, 56% of daily users died within five years, compared to just 5% of non-users. These are differences too large to ignore.

Why the risk might be higher​

Researchers believe that THC, the main psychoactive ingredient in cannabis, may weaken the body’s cancer defenses.

THC could promote inflammation in the colon and suppress T cells, which help destroy cancer cells. Chronic inflammation also increases cell turnover, increasing the chance of dangerous mutations.



Mental health issues linked to heavy cannabis use may also interfere with patients’ ability to stick with treatment plans.

A rising health concern​

Cannabis use is at an all-time high in the U.S., with over 18 million Americans reportedly using it daily or nearly daily. Among adults aged 18 to 25, about 4.5 million report using it this frequently.

Meanwhile, colon cancer diagnoses in young people are expected to rise by 90% between 2010 and 2030.

With both cannabis use and colon cancer on the rise, the connection warrants close scrutiny.

What is cannabis use disorder?​

CUD occurs when cannabis use interferes with daily life, impacting work, relationships, and responsibilities.


In the study, 8 out of 10 daily users met the criteria for CUD. While only 3% of all participants had CUD, the associated risks were significantly higher.

This underscores how heavy, frequent use may carry serious consequences.

But what about the “benefits” of cannabis?​

Some lab studies have suggested that certain compounds in cannabis might slow cancer cell growth.

However, most of these involve synthetic cannabinoids in controlled settings, not real-world use by patients.

As Dr. Raphael Cuomo, co-author of the study, explains: “This isn’t about vilifying cannabis. It’s about understanding its full impact, especially for those facing serious illnesses.”

A call for more research and more conversation​

Experts agree: more studies are needed to understand how cannabis use affects cancer biology.

But these early findings are a wake-up call.

As more Americans turn to cannabis, public awareness about its potential health risks, especially when used heavily, must keep pace.

Education, not fear, is the key to better health choices.


Read more:

• This everyday relaxation habit could be quietly raising your dementia risk by 72%
• New study uncovers disturbing link between a household favorite and rising cancer cases

Have you or someone you know used cannabis while managing a health condition? Are you surprised by these findings? Do you have questions about cancer prevention or cannabis safety? Share your thoughts and experiences in the comments—we’d love to hear from you.