Concerning rise in colorectal cancer among young people points to gut bacteria

The bacterium called Fusobacterium nucleatum (F. nucleatum) could be the culprit behind an unexpected rise in colorectal cancer among young people, according to a 2020 study from Georgetown University. The research indicates the importance of healthy gut bacteria in the prevention of diseases like cancer. Initial findings are part of an ongoing study from researchers at Georgetown Lombardi Comprehensive Cancer Center and raise awareness on the correlation between gut bacteria and cancer outcomes. 

Possible Culprit

Although colorectal cancer has been steadily declining among people over 55, rates among younger people have been climbing at an annual rate of 2% in people under 55. Some possible reasons behind the dramatic uptick include obesity, diabetes, and diets low in whole grains. Screening for the disease has generally not been suggested for those under 50, while older populations benefit from preventative treatments like colonoscopies. 

“We haven’t seen large genetic differences in colorectal tumors from younger versus older people, so we hypothesize that something else, perhaps the microbiome, is contributing to the rise in incidence of the disease in younger people,” says Benjamin Adam Weinberg, MD, an assistant professor of medicine at Georgetown Lombardi in a statement

Surprising Results

Microbes within the microbiome, which include a variety of viruses, fungi, and bacteria, can irritate the lining of the colon, resulting in inflammation. This can lead to cancer because of mutations in the DNA of cells in the colon. Researchers have been aware for some time that F. nucleatum can suppress the body’s immune response in the colon, thereby promoting cancerous growth. Weinberg and his team examined the DNA, microbiome, and available healthy tissue of tumors from 31 patients with colorectal cancer who contracted the disease either before they were 45 years old or after they were 65 years old.

Overall results indicated 478 bacterial and fungal varieties in the tumors. The most common was F. nucleatum, which appeared in a larger percentage of tumors from young people. “There was a much higher presence of F. nucleatum in younger patients than we expected,” says Dr. Weinberg. “As to whether this bacterium alone can explain some of the rise in incidence of colorectal cancer in younger people is something we need to explore, and to aid in that effort this ongoing study will incorporate tumors from up to a total of 144 people.”


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