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Microbes, Mutagens, and Mortality: CRC in a Younger Generation
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Released: January 28, 2026

John Marshall
John Marshall, MD
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Microbes, Mutagens, and Mortality: CRC in a Younger Generation

 

John Marshall, MD: John Marshall Oncology Unscripted. A lot of good data coming out on all sorts of things. You know, I'm a colon cancer guy, so I really want to talk about two clinical trials in the colon cancer space.

 

One was a paper in Nature—it's actually a few months old—but, you know, I keep seeing all these young people with colon cancer, and I keep thinking: it's the microbiome. It's gotta be. And this paper actually found a version of E. coli that produces a toxin that, if you're exposed to it at a young age—say 10, 11, 12 years old—it dramatically increases your risk of getting colon cancer later.

 

Now, I sort of didn’t think of it as one bacterium causing one toxin causing a toxicity. I always thought it was more of a gamish—what swamp do you have? What's the nature of your rainforest, your bacteria in the colon, that's causing it? But what I'm excited about is that we're continuing to see, week after week, month after month, new data that supports a better understanding of the microbiome—one that we hope will translate into not just identifying people who are at risk for early-onset colon cancer, but, as you know, other diseases as well.

 

And as a related story—this comes out of Cancer Investigation—patients who are taking GLP-1 drugs had lower colon cancer death rates. So basically, they looked at colon cancer patients, and the strongest signal was in those who were obese. But if you were on a GLP-1 versus not on a GLP-1, your survival was much better on one.

 

So, again, how do GLP-1 drugs work? Uh, we don’t really know. But I think probably our interface with our microbiome is one of the ways they have an effect. And so it kind of feeds back to this: the healthier we can get our innards, our inner colony of bacteria—I really think it's where our soul resides—the healthier we can get that, the better our outcomes will be. Again, not just for colon cancer, but for other diseases as well.

 

Just some high-level stuff that you probably didn’t see in your scanning of the week’s journals.

 

John Marshall, Oncology Unscripted.