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Gut Feeling: Is Our Microbiome the Key to Better Cancer Care?
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Released: October 22, 2024

Expiration: October 21, 2025

John Marshall
John Marshall, MD

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Gut Feeling: Is Our Microbiome The Key To Better Cancer Care?

[00:00:05] John Marshall, MD: Today, really what I want to focus on for our main topic is something that, I don't know, doesn't have a lot to do with IV fluids. It has a lot to do with our world around us and our world inside of us. And this is what we call our microbiome. And you might know why I'm thinking about this a lot. It’s really all about understanding a couple of things that have emerged. One is, why are some people responding to immunotherapies and certain diseases and certain locations of that disease are responding to immunotherapy and some are not.

And on the other side, that really touches my world a lot, is this new phenomenon of young people with colorectal cancer all of a sudden coming up with this disease, and those are young, healthy people in their twenties, thirties and forties. Almost every one of them, 90 percent of those tumors, are in the rectal sigmoid space. So not the distribution that we're used to seeing in colon. So, what the heck's going on there? And we think both of these things. may have something to do with the microbiome.

Well, we are medical professionals, so we must be, in fact, experts in the microbiome, right? We all went to medical school or some sort of medical training, and of course, while we were there, we learned about the bacteria that lived in and around us. Or did we?

The reality is, at least in me when I went to medical school, you know, a thousand years ago, and even today, the current curriculum, only a few hours of the four years of medical school are spent on understanding bacteria and other critters that live In our bodies and on the surface of our bodies, you know, you memorize the bacteria that are there, you get it right on the test, and then you forget about it.

And now, though, we're recognizing that maybe just maybe this is an incredibly important part of our overall health. We did evolve. I think you believe in evolution, with bacteria inside of us, and it's not just that bacteria that we can collect and measure in our poop. The way I'm increasingly thinking about it is it's a bunch of lakes of different ponds of different kinds of bacteria, different concentrations of bacteria that live in different parts of our body. Probably connected to each other, but maybe lake one can't really see what's going on in lake four, if you will, because they're different pools going on there.

we don't even know how to measure it. You know, we, you go to the CVS. And you'll be able to see clear as day on that aisle that they seem to know about microbiome. There's rows of probiotics that you can take and buy and take at any drug store anywhere in the country, which suggests that somebody thinks they know how to make a healthy microbiome.

I'm not sure I do. There's certainly no button in my electronic medical record that I can click and say, let's do a microbiome test on this patient. And so, we need to understand better what the heck's going on with our microbiome. We need to study it. We need to do deep dives on it so that we can Understand what it has to do with our health, how to make a good one, and from that, I think we'll have great advances in the treatment, not only of cancer, but many, many diseases.

SCIENCE NEWS: MICROBIOME AND IMMUNOTHERAPY

[00:003:49] The reason I wanted to focus on this this week is that this week's JCO had 2 papers in it that actually bring this point solidly forward. One is a lung cancer paper. What this group did was look at the Escherichia association. What the heck is Escherichia? You know it as "E." in E. coli. So, they were looking for evidence of Escherichia in the tumors of patients with lung cancer. These are non-small cell lung cancer patients, and they were looking at immune checkpoint inhibition and the outcome if you had the bacterial presence there versus not. And the reality was there was a big delta. In outcome if the tumor had the Escherichia present in it.

So, this was really strong evidence that some microbiome presence in the tumor was in fact going to improve the outcome with immunotherapy. So, this was controlling for PD-1 and all of those other different variables. But this was a very important observation.

So important that there's a beautiful little editorial that goes along with it.

The second paper in the same article was more in my area. And this was a rectal cancer study. And in this study, you may have seen some of the data where in microsatellite stable rectal cancers, there have been some combinations of immune therapy generating some responses. Well, you know, in metastatic microsatellite stable patients, we're not seeing much in the way of responses, at least not in liver mets, et cetera. We see an occasional one in lung metastases. So, what they did was they took microsatellite stable rectal patients and not only gave them chemo, which would be the normal thing to do, they gave them combo immunotherapy as well. And lo and behold, in this group of patients at a 50 percent path CR rate. Now that's much better than one gets with chemotherapy alone, much better. And so, it suggests that when the tumor is still in the primary location, maybe some juxtaposition, maybe some overlay with microbiome, some interaction with microbiome there locally, but we saw a much better benefit when there was some microbiome in the neighborhood. So, both these papers suggest that immunotherapy may have some role to play.

You know very well, all of us cite the data, in mostly kidney cancers, sometimes in melanomas, where you took stool transplants, so you're going to borrow somebody's microbiome, who's a responder. And just think about this, you don't know what's in there, but you know that that person seems to be benefiting, so maybe if I gave them and this other patient who's not benefiting with this stool, then they would benefit. Lo and behold, some of those people benefit. So, we know, we can see it, that there's something going on with the bacteria inside of us that's influencing our health, our response to therapies, etc.

I am not an expert in the microbiome. I'm trying to be. I'm actually trying to learn and see what's out there. There isn't a lot. There's not a lot of publications in space, and I think a lot of people are picking and choosing. We are just starting, if you will, in this science, and we need to hurry up and figure this out.

So, stick around and watch a couple of interviews that we've got with people who are really smart about this. One is somebody who's really looking at the science behind microbiome. How do we measure it? What's going on there? What's a good one? But another is one of us, an oncologist, who's actually applying this microbiome thoughts, beliefs, to prospective clinical trials and getting some very interesting results. Click on the next one and watch these interviews. 

Learn more by watching:
Candid Conversations With the Experts: Microbiome Matters: Interviews With Christian Jobin, PhD and Sumanta K. Pai, MD

MedBuzz: The Impact of Nationwide IV Fluid Shortages

This transcript has been lightly edited for clarity.