Gut bacteria may explain rising colon cancer diagnoses in young people

• A new study analyzed the gut microbiomes of people who get colon cancer early in life versus those who get the disease later in life.
• Some strains of bacteria are more present in the intestines of young colorectal cancer patients than in older ones.
• Colon cancer in people under age 55 has been on the rise over the past two decades.

The gut microbiome, or the colony of bacteria that live in our large intestine, could hold an important key to helping determine whether a young person will develop colon cancer, a new study suggests.

Scientists know that certain bacteria can disrupt the lining of the colon, leading to tumor formation and cancer development. Building on this, researchers at Georgetown University set out to find out which strains of bacteria are more present in the guts of young people who get colon cancer.

Georgetown researchers analyzed the bacteria in the tumors of 36 people under age 45 with colon cancer versus those of 27 people over age 65 with the disease.

They discovered 917 unique bacterial and fungal species in the tumors; various bacteria, including cladosporium, were more present in the guts of younger colon cancer patients, while others, such as Moraxella osloensiswere more common in the older patients.

“We have trillions of bacteria in our bodies, including in our gut, some of which are involved in the development of colorectal cancer, so we think the microbiome may be an important factor in the development of the disease,” Benjamin Adam Weinberg, an associate professor of medicine at Georgetown and lead author of the study, said in a release.

Weinberg told Axios that his team’s findings indicate that the composition of the gut microbiome may determine how quickly a person gets colon cancer, but it’s too early to say for sure. And since diet and environmental factors influence the composition of the microbiome, a better understanding of what it looks like in colon cancer patients could help determine which foods to avoid for prevention.

Weinberg and other researchers will present their findings at the 2023 annual meeting of the American Society of Clinical Oncology in Chicago in June.

People are diagnosed with colon cancer at a younger age

More young people are being diagnosed – and dying from – colon cancer. The proportion of colon cancer among people under age 55 doubled between 1995 and 2019, from 11% to 20%, according to the American Cancer Society, while the overall incidence of colon cancer in the US declined.

Scientists predict that by 2030, the disease will be the leading cause of cancer death in people under the age of 50.

Colorectal cancer has a high survival rate if caught early, but young people are usually not diagnosed until the disease has reached an advanced stage: more than half of people under 50 are diagnosed at stage three or four, compared with just 40 % of people over 50 diagnosed in those later stages.

They have suspicions, but researchers aren’t sure why more young people are getting colon cancer. High-meat diets — such as the popular carnivore and keto diets — may increase your risk of colon cancer, according to the National Institutes of Health. Rising obesity among young people could also play a role in the trend.

Doctors are calling for more testing for colon cancer, especially for people with a family history or risk factors. Scientists recently identified four different symptoms — abdominal pain, rectal bleeding, diarrhea and iron deficiency — young people with colon cancer are more likely to experience.