Scientists find new gut virus linked to colorectal cancer that could lead to earlier diagnosis

More than 55,000 Americans are expected to die of colorectal cancer this year NewsHealthScientists find new gut virus linked to colorectal cancer that could lead to earlier diagnosisMore than 55,000 Americans are expected to die of colorectal cancer this yearJulia Musto in New York Friday 20 February 2026 20:23 GMTBookmarkCommentsGo to commentsBookmark popoverRemoved from bookmarksClose popoverColorectal cancer rising in younger adultsYour support helps us to tell the storyRead moreSupport NowFrom reproductive rights to climate change to Big Tech, The Independent is on the ground when the story is developing. Whether it's investigating the financials of Elon Musk's pro-Trump PAC or producing our latest documentary, 'The A Word', which shines a light on the American women fighting for reproductive rights, we know how important it is to parse out the facts from the messaging.At such a critical moment in US history, we need reporters on the ground. Your donation allows us to keep sending journalists to speak to both sides of the story.The Independent is trusted by Americans across the entire political spectrum. And unlike many other quality news outlets, we choose not to lock Americans out of our reporting and analysis with paywalls. We believe quality journalism should be available to everyone, paid for by those who can afford it.Your support makes all the difference.Read moreScientists have discovered a new virus found in common gut bacteria that is linked to colorectal cancer. It’s not yet clear whether the virus helps to actually cause the cancer or if it’s simply a sign that something in the gut has changed, but researchers at the University of Southern Denmark say the colorectal cancer patients they studied were more likely to have the virus than others without the cancer.The scientists believe the findings could help to improve colorectal cancer screening, and tests for the virus could potentially lead to earlier detection, though more studies need to be done before those tests could be created.Still, detecting colorectal cancer early is crucial, as that can dramatically improve patients’ survival rates and allow doctors to remove precancerous growths before they become harmful.Colorectal cancer is expected to result in 55,230 deaths in the U.S. this year, according to the American Cancer Society, and is the second-most common form of cancer for both men and women.open image in galleryColorectal cancer is responsible for tens of thousands of deaths in the U.S. every year. Now, Danish researchers say they’ve found a virus that’s linked to the disease (Getty Images for Fight Colorectal Cancer)Crucial curiosityThe research started with Bacteroides fragilis, a bacterium that scientists have examined for years. It’s the most common cause of anaerobic infections in humans, according to the National Institutes of Health, but is also found in people who never develop cancer. “It has been a paradox that we repeatedly find the same bacterium in connection with colorectal cancer, while at the same time it is a completely normal part of the gut in healthy people,” Dr. Flemming Damgaard said in a statement.Damgaard and the team decided to look at whether there are differences within the bacterium. They looked at data from two million Danish patients and singled out those who had experienced a serious bloodstream infection caused by the bacterium. Several of those patients were diagnosed with colorectal cancer within just weeks.The researchers analyzed the bacterium’s genetic material in patients with and without cancer, which is how they first found that bacteria from cancer patients were more often infected with specific viruses.Next, they analyzed stool samples from nearly 900 people in the U.S., Europe and Asia, finding that those with colorectal cancer were approximately twice as likely to have traces of these viruses in their gut, including the previously undescribed virus. “The number and diversity of bacteria in the gut is enormous. Previously, it has been like looking for a needle in a haystack. Instead, we have investigated whether something inside the bacteria – namely viruses – might help explain the difference,” said Damgaard.open image in galleryColorectal cancer rates are rising in young people. While that’s partially due to a lowered screening age, experts believe gut health is also a factor (Getty Images for Fight Colorectal Cancer)Future steps forward Damgaard is working to examine how gut tissue, the bacterium and the virus interact, as well as looking for it within colorectal cancer tumors and seeing if mice genetically predisposed to develop cancer get it more quickly with the virus in their gut.While it’s too soon to create tests for the virus, preliminary analysis showed the virus could identify around 40 percent of cancer cases, the researchers said.“In the short term, we can investigate whether the virus can be used to identify individuals at increased risk,” said Damgaard.Colorectal cancer is detected primarily through cancer screening, including stool and blood tests