A Virus Linked to Increased Risk of Colorectal Cancer Discovered 0 18

Scientists from the University of Southern Denmark have identified a previously uncharacterized virus that is more frequently found in patients with colorectal cancer. This virus is a bacteriophage — a virus that lives inside the intestinal bacterium Bacteroides fragilis. The study is published in the journal Communications Medicine (CM).

The bacterium Bacteroides fragilis has long been associated with colorectal cancer; however, it is also present in most healthy individuals. The authors decided to study not the bacterium itself, but its 'internal content.' It turned out that patients who were later diagnosed with cancer had Bacteroides fragilis significantly more often infected with a specific virus.

The first signal was found in Danish clinical data, and the researchers then tested the hypothesis on an international sample of 877 individuals from Europe, the USA, and Asia. Patients with colorectal cancer had traces of these viruses in their intestines about twice as often. At the same time, the scientists emphasize that this is a statistical correlation, not proof of the virus's causal role in tumor development.

The authors believe that if the virus indeed alters the properties of the bacterium, it could affect the microbial ecosystem of the intestine and create conditions for carcinogenesis. In the future, such viral markers could theoretically be used for screening: in preliminary analysis, individual viral sequences allowed for the identification of about 40 percent of cancer cases with low prevalence among healthy individuals.