Bacteria Differ in Stages of Colon Cancer Diagnosis

Gut microbiota is the largest microbiome in the body, with at least 1,000 types of bacteria and 100 trillion microbes. Gut bacteria maintain intestinal stability and can influence susceptibility to disease. No one’s microbiota is the same as another person’s. The composition can change over time, especially in the early stages of certain diseases.

A recent study found that the microbiome of colon tumors varies depending on whether the patient was diagnosed with early-onset (younger than 50) or late-onset disease.

Study finds difference in colon tumor microbiomes.

According to new research from Georgetown University’s Lombardi Comprehensive Cancer Center, the microbiome of patients with colon cancer can differ greatly.

The research team found the type and amount of viruses, fungi and bacteria in the colon tumors of patients differed notably depending on whether the patients were diagnosed with early-onset colon cancer compared to late-onset colon cancer.

Increase in early-onset colon cancer

Colon cancer is one of the most common types of cancer, with approximately two million new cases per year worldwide. Colon cancer rates have been decreasing in adults older than 55, partly due to increased screening for the disease. However, colon cancer incidence continues to rise in young adults. In the last 10 years, the number of young adults with colon cancer has doubled, and the incidence rate has increased from 11 percent in 1995 to 20 percent in 2020.

Gut microbiota and colon tumors

Only about 10-15 percent of colon cancers are hereditary, so most colon cancers develop due to environmental factors. In recent years, scientists have placed more importance on the gut microbiome as a factor contributing to the development of colon cancer. Microbes can cause inflammation in tissues, which can mutate DNA cells in the colon lining. Scientists also know a certain type of bacteria called Fusobacterium nucleatum (F. nuc) can suppress the immune response in the colon and make it more prone to cancer.

The study examined 917 types of fungi and bacteria in the colon tumors. F. nuc was one of the most common types of bacteria, and it appeared in about 30 percent of both early- and late-onset colon tumors. The researchers were also able to categorize specific bacteria and fungi that were more common in early-onset tumors while others were more common in late-onset tumors.

“Younger people with colorectal cancer have more biologically aggressive cancers, and whatever survival benefit they have by being younger is outweighed by the more aggressive tumor biology. We also know that, for the most part, genetics doesn’t explain the recent rise in young-onset disease,” said Benjamin Adam Weinberg, MD. “But we have trillions of bacteria residing in our body, including in our gut, some of which are implicated in the development of colorectal cancer; hence, we think the microbiome may be an important factor in the development of the disease, as it is involved in the interplay between a person’s genetics, environment, diet and immune system.”

Dr. Weinberg is an associate professor of medicine at Georgetown Lombardi. He hopes the new study may provide insight into why young-onset colon cancer rates continue to increase. With the current findings and plans to continue the research, the team wants to continue to explore how the microbiome and other factors influence colon cancer development. Analyzing the gut microbiota could provide critical information on how to target this microbiome for more sophisticated treatments.

Schedule a colonoscopy for digestive health.

When was the last time you had a colonoscopy? The American Cancer Society recommends that all adults at average risk for colon cancer begin screening at age 45, but certain risk factors may require earlier screening. Talk to your doctor about getting screened at appropriate times.