Gut Microbiome Changes Linked to Colon Polyps: A Potential Precursor to Cancer

Colon polyps, abnormal growths in the colon or rectum, have the potential to develop into cancer over time. Recent research conducted by scientists from Mass General Brigham reveals a significant connection between specific gut bacteria and the formation of precancerous polyps in the colon, offering potential insights into diagnostic procedures and treatments.

Co-corresponding author Dr. Daniel C. Chung, a medical co-director at the Center for Cancer Risk Assessment and a faculty member of the Gastroenterology Division at Mass General Cancer Center, explains that while previous studies have explored the relationship between the gut microbiome and cancer, this new study delves into understanding how the microbiome influences the development of precancerous polyps. The findings suggest that intervention through the microbiome presents an opportunity to prevent the formation of colorectal cancer.

Colorectal cancer is the second most lethal form of cancer in the United States and is increasingly affecting younger adults. The vast majority of colorectal cancers originate from precancerous polyps, emphasizing the importance of halting the progression at this stage to reduce colorectal cancer rates effectively.

Polyp development can occur in different ways, with tubular adenomas and sessile serrated polyps being the two main types. Lifestyle factors such as obesity, low physical activity, a diet high in red and processed meats, smoking, and alcohol use contribute to the risk of colorectal cancer and polyps. These factors also impact the composition of the gut microbiome, which consists of the bacteria residing in our intestines.

Researchers believe that these environmental factors may promote polyp growth in two ways: either by directly altering the gut microbiome to encourage polyp growth or by promoting polyp growth, which subsequently affects the gut microbiome by directly influencing the cells lining the intestines.

While previous smaller studies have not found consistent patterns linking the gut microbiome to polyps, the Mass General Brigham researchers aimed to investigate this connection further. They analyzed data from 1,200 individuals who underwent routine screening colonoscopies, gathering information on health, diet, medications, lifestyle, and analyzing stool samples to determine the bacterial composition of the gut microbiome. This extensive study, conducted under the GI Disease and Endoscopy Registry (GIDER) program at Massachusetts General Hospital, represents the most comprehensive research of its kind, providing in-depth understanding of gastrointestinal diseases. The ongoing data collection through this registry enables long-term follow-up studies.

By comparing the gut microbial signatures of individuals without colon polyps to those with tubular adenomas or sessile serrated adenomas, the researchers identified distinct clusters of bacterial species associated with each polyp type. Nineteen bacterial species showed significant differences in patients with tubular adenomas, while eight species differed significantly in patients with sessile serrated adenomas.

The authors acknowledge that the study population was predominantly white, limiting the generalizability of the findings to other racial groups. Additionally, the study cannot determine whether bacterial species or changes in adenoma tissue occur first. The next step for researchers is to isolate specific bacteria species present in the gut and investigate their functional relationships with polyp growth through laboratory models. This knowledge could aid in the development of probiotics or treatments to reduce colorectal cancer risk or serve as a screening method to assess polyp or colorectal cancer risk.

Dr. Chung emphasizes that the ultimate goal is to modify specific aspects of diet or the gut microbiome to alter the natural progression of polyps, potentially preventing colorectal cancer altogether.

The study received partial funding from the Center for Microbiome Informatics and Therapeutics at MIT, the Center for the Study of Inflammatory Bowel Disease, and the National Institutes of Health. The researchers also disclosed various affiliations and potential conflicts of interest with organizations such as Celsius Therapeutics, Jnana Therapeutics, Nestle, Moonlake Immunotherapeutics, AMILI, Guardant, Pfizer, Takeda, Arena, Boston Pharmaceutics, Gelesis, GI Supply, Ironwood, and Urovant.

Frequently Asked Questions (FAQs) about colon polyps

More about colon polyps

• “Association of distinct microbial signatures with premalignant colorectal adenomas” (Cell Host & Microbe)
• Mass General Brigham: https://www.massgeneralbrigham.org/
• Center for Cancer Risk Assessment at Mass General Cancer Center: https://www.massgeneral.org/cancer-center/prevention-and-screening/center-for-cancer-risk-assessment
• GI Disease and Endoscopy Registry (GIDER) at Massachusetts General Hospital: [Link not available]
• Center for Microbiome Informatics and Therapeutics at MIT: [Link not available]
• National Institutes of Health: https://www.nih.gov/