Scientists have made a groundbreaking discovery linking a single type of bacteria to colorectal cancer. The bacteria, Fusbacterium nucleatum, typically found in the mouth, has been identified as a potential contributor to the growth of colorectal tumors.

The human gut is home to trillions of bacteria, with some playing beneficial roles such as aiding in food digestion, while others can lead to conditions like stomach ulcers. Tumors in the lower intestines, including the colon and rectum, are in constant contact with a variety of gut bacteria, sparking curiosity among researchers about the impact of certain bacterial species on colorectal tumor growth.

Recent studies have pointed to Fusobacterium nucleatum as a key player in the development of colorectal cancer. Despite its usual presence in the mouth, elevated levels of F. nucleatum have been observed in the intestines of individuals with colorectal tumors compared to those without cancer.

In a new study published in Nature, researchers supported by the National Cancer Institute have identified a specific subtype of F. nucleatum, known as Fna C2, as the bacteria responsible for fueling cancer growth. Lab experiments demonstrated the ability of this bacterium to survive in acidic conditions mimicking the stomach and promote the formation of precancerous growths in the large intestine of mice. Additionally, it produced compounds conducive to tumor growth.

An analysis of tissue samples from colorectal cancer patients revealed that this particular type of F. nucleatum was more prevalent in tumor tissue than in nearby healthy tissue. Individuals with colorectal cancer were found to be five times more likely to harbor this bacterium in their stool compared to those without the disease.

Co-lead researcher Susan Bullman, Ph.D., from Fred Hutch Cancer Center, emphasized the importance of this discovery, noting that understanding the role of microbes in disease progression opens up possibilities for targeted interventions. By recognizing that this specific bacterium is actively contributing to cancer development, researchers can explore strategies to prevent its impact.

Phil Daschner, a program director at the National Cancer Institute’s Division of Cancer Biology, who was not part of the study, underscored the significance of comprehensively studying the behavior of various microbes in the lower intestines. He highlighted that gut microbes encompass not only bacteria but also fungi and viruses, some of which may influence cancer development.