Hidden Influence of Gut Microbiome on Early-Onset Colorectal Cancer

Colon cancer's hidden link revealed in microbiome study.

A study on the microbiome of people with colon cancer was undertaken by a team of researchers from Georgetown University's Lombardi Comprehensive Cancer Centre.

They discovered significant variations in the bacteria, fungi, and viruses detected in tumors of individuals with early-onset (age 45 or younger) and late-onset (age 65 or older) disease.

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These findings have the potential to shed light on the increased incidence of colorectal cancer among young people who do not have identified risk factors for the illness.

The outcomes of the study will be presented in June at the American Society of Clinical Oncology's annual meeting in Chicago ().

The presentation of these data will take place at the American Society of Clinical Oncology's annual meeting in June. While the incidence of colorectal cancer has been decreasing in those over the age of 55 due to improved screening procedures such as colonoscopy, the number of cases in young persons under the age of 55 has nearly doubled in the last decade. The rate of occurrence has climbed from 11% in 1995 to 20% in 2020, indicating a worrying trend.

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“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, an associate professor of medicine at Georgetown Lombardi. “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.”

Decoding the Microbial Puzzle

Scientists have known for a while that certain microbes can disturb the lining of the colon and promote tissue inflammation. This can result in mutations to the DNA of cells in the colon and lead to cancer. Researchers also know that one type of bacteria, Fusobacterium nucleatum (F. nuc), can promote cancerous growth by suppressing immune responses in the colon.

To better understand the role of the microbiome and how its influence varies depending on a person’s age of onset of colorectal cancer, Weinberg and colleagues looked at the DNA and the microbiome of tumors from 36 patients with colorectal cancer who were diagnosed before age 45 as well as specimens from 27 people who were diagnosed after age 65.

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Overall, the investigators detected 917 unique bacterial and fungal species in the tumors. One of the most common bacteria found was F. nuc, which appeared equally in about 30% of both early and late-onset tumors. Differences were seen in Cladosporium sp., which was found more commonly in early-onset disease, whereas Pseudomonas luteola, Ralstonia sp., and Moraxella osloensis were seen more commonly in late-onset disease. In terms of composition, Clostridium perfringens, Escherichia coli, Leptotrichia hofstadii, Mycosphaerella sp., Neodevriesia modesta, Penicillium sp., and Leptosphaeria sp., each made up 11% of the microbiome in people with the late-onset disease but these organisms were not found at all in people with early-onset disease.

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Weinberg says with the current data, and with future efforts to collect more samples, they anticipate expanding their research efforts to continue exploring the relationship between the microbiome and other factors that contribute to colorectal cancer.

“Because we have tumor genetic data and diet questionnaire results from many of our patients, we hope to explore more relationships and other aspects of how the microbiome impacts colorectal cancer progression in the future,” said Weinberg. “We are also interested in the circulating microbiome, such as bacteria that could be picked up in a blood sample, and how this correlates with bacteria in the gut and in the tumor.”

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Reference:

Gut Microbiota Profiles in Early- and Late-Onset Colorectal Cancer: A Potential Diagnostic Biomarker in the Future - (https://karger.com/dig/article/102/6/823/828006/Gut-Microbiota-Profiles-in-Early-and-Late-Onset)

Source-Eurekalert