Scientists search the microbiome for clues to the rise in colorectal cancers

Scientists search the microbiome for clues to the rise in colorectal cancers April 27, 20265:00 AM ET Heard on Morning Edition Yuki Noguchi What is behind the rise in younger colorectal cancers? Listen · 3:43 3:43 Transcript Toggle more options Download Embed Embed <iframe src="https://www.npr.org/player/embed/nx-s1-5766512/nx-s1-9745949" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player"> Transcript DrAfter123/Digital Vision Vectors/Getty Images Like so many in her field, The Ohio State University oncologist Ning Jin is alarmed by the number of patients in their 30s and 40s with late-stage cancer in their lower digestive tract. It's not just that these patients are decades younger than what had been typical for colorectal cancer; Jin says the tumors themselves are also more stubborn to treat. "Even though we treat young patients with more aggressive chemo — more chemo or more surgery — patients' outcomes are not necessarily better," Jin says. And the disease has become the top cancer killer among people under 50 — even as death rates decline in older age groups. Sponsor Message Shots - Health News From anxiety to cancer, the evidence against ultra-processed food piles up Advances in science in recent years have made many cancers more treatable and survivable — but not colorectal cancer, which has become more lethal, striking people at younger ages. And it's occurring more often too. What's causing the rise in cancers among younger patients — not just of colorectal, but all forms — is a huge medical mystery. Increasingly, doctors suspect that the gut's microbiome is a key actor behind these forms of cancer in particular. Patient advocates say it's critical that more people — especially young adults with a family history of these cancers — get diagnostic testing. Preventive testing isn't regularly recommended and covered by insurance until age 45. But young people should keep an eye out for symptoms, advocates say, and raise the issue with their doctor. A generational change Genetics plays some role in colorectal cancers. Jin says as many as a fifth of patients have hereditary markers — like a genetic mutation for Lynch syndrome — that increase the risk of getting colorectal cancer, among others. But genetics do not explain what drives the vast majority of cases — about 80% of colorectal cancers. So Jin and others have concluded: "There must be some environmental factors or changes." Life, after diagnosis More young people are surviving cancer. Then they face a life altered by it It is highly unusual to see dramatic changes in disease patterns within a single generation. But that's precisely what veteran oncologist Dr. John Marshall, head of clinical research at the Lombardi Cancer Center at Georgetown University, has observed. "Thirty-plus years ago, when I first started, no one — no one; zero number of patients — were in my clinic under the age of 50 with colon cancer," he says. "And now it is almost half of the patients that I see." Marshall says there are other changes in disease pattern, too: Earlier onset tumors tend to show up differently — more tumors are found near the rectum, lower in the tract. Sponsor Message Clearly, something correlating with a generational change is shaping this disease. Potential culprits Experts suspect several factors may be leading to these more frequent, virulent cancers: One is our greater reliance on ultra-processed foods, as well as plastics and chemicals…

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