Persistent gut microbiome changes linked to sustained colorectal cancer risk

Removing a precancerous mass, known as an adenoma, from the colon is one of the most effective tools for preventing colorectal cancer (CRC). However, a new study suggests that this procedure may not fully return the gut to a low-risk state.

Researchers found that alterations to the gut microbiome and metabolites can persist for more than a decade after an adenoma is removed. These lasting changes may drive a sustained and heightened risk of developing colorectal cancer.

Long-Term Microbial Alterations

The study utilized health data and stool samples from women enrolled in the Nurses’ Health Study II. Researchers compared 354 participants who had undergone adenoma removal with 354 adenoma-free participants matched in age and background.

On average, stool samples were collected 12 years after the adenoma removal. The findings revealed that significant differences in the gut microbiome and metabolites remained even after this long interval.

Did You Know? Colorectal cancer is the second leading cause of cancer-related death worldwide.

The microbiomes of those who had an adenoma removed partially resembled the microbiomes of patients already diagnosed with CRC. This suggests that the biological environment of the gut may remain altered long after the physical mass is gone.

The Impact of Lifestyle Choices

The research also identified a strong connection between lifestyle habits and the abundance of CRC-associated microbes. This link was particularly pronounced in individuals with a history of adenoma.

Colorectal Cancer and the Gut Microbiome, What Science Reveals

Among those who had previously had an adenoma removed, participants with lower physical activity and less healthy diets carried more of the microbes typically elevated in both adenoma and CRC patients.

Expert Insight: Samantha Carter notes that these findings highlight a critical gap in post-procedure care. While the surgical removal of a precancerous mass is a vital first step, the persistence of microbial alterations suggests that biological risk is not entirely eliminated by the procedure alone.

These connections between lifestyle and gut microbes were found to be tighter in the high-risk group than in participants who were adenoma-free.

Future Directions in CRC Risk

While the study demonstrates a clear association, the researchers emphasized that it does not prove causation. The gut microbiome is a plausible suspect in sustained risk, but further testing is required.

A possible next step for researchers is to directly test whether modifying the gut microbiome through exercise and diet habits successfully alters CRC risk.

Such findings could lead to more personalized lifestyle interventions for people at higher risk. This may help in managing the gut environment to potentially lower the likelihood of cancer recurrence.

The study is published May 27 in Cell Host & Microbe here.

Frequently Asked Questions

What is an adenoma?
An adenoma is a precancerous mass found in the colon.

How long did the researchers track the participants?
Stool samples were collected from participants an average of 12 years after their adenoma was removed.

Does removing an adenoma completely eliminate the risk of colorectal cancer?
No. People who have had this procedure still face an elevated risk of CRC, and the study suggests the gut microbiome may be a biological contributor to this sustained risk.

How do you incorporate gut-healthy habits into your daily routine?