Researchers investigating colon cancer say they may have identified another factor that could contribute to the disease, as diagnoses continue to climb among younger adults.
In the US, colon cancer affects roughly 160,000 people each year, and around 55,000 people die from the condition annually.
Although cancer risk typically increases with age, recent data suggests colon cancer is becoming more common in a different group: younger patients.
Studies indicate rates in people under 50 have risen by roughly three percent since 2018, raising concerns among clinicians and scientists trying to understand what’s driving the change.
Now, a new line of research points to a possible link involving “prophages” — a term used when a bacterium becomes infected by a virus.
Viruses are far smaller than bacteria, so it’s possible for bacteria to be infected by viruses, even though both are microscopic.
These bacteria-infecting viruses are known as bacteriophages, and they don’t infect human cells directly.
However, while the viruses might not attack human tissue themselves, they can alter how bacteria behave — and those changes may have knock-on effects for health.
In Denmark, scientists analyzed bacterial samples taken from 48 people with bloodstream infections; half of those patients also had colon cancer.
Comparing the two groups, the researchers reported that the cancer patients shared a bacterium called B. fragilis that contained two previously unseen prophages.
Among participants without cancer, those prophages were not found.
A closer look at the prophages suggested they didn’t carry any known cancer-promoting genes, though the team said more work is needed to understand what they might be doing in the gut environment.
In a second phase, the researchers examined stool samples from 877 people across Europe, Asia, and the US, with about half of the participants diagnosed with colon cancer.
They observed a similar trend in that larger dataset, again linking the presence of these prophages with cancer cases.
Even so, the authors stressed that this is only a correlation at this stage.
It remains unclear whether the bacteria-virus combination contributes to cancer development, or whether it appears as a result of other changes associated with the disease.
Dr Fleming Damgaard, a molecular biologist who led the project, said: “These findings suggest a partnership between bacteria and their viruses that may shape disease.
“If confirmed, this… may support earlier detection of colorectal cancer and guide new ways to treat and prevent this disease.”