Colon Cancer: Should Young People Worry?

Colorectal cancer has long been thought of as a disease of older folks. But that's changing — fast. Rates in older people are actually going down, and more and more people under 50 are getting this disease. And a surprising number of them are dying from it. So what’s going on here? We dig into why young people are getting hit harder. Plus, we often hear that you should watch out for changes in your poo. But what changes?? We’ll find out. We talk to gastrointestinal medical oncologist Dr. Michael Foote and cancer biologist Prof. Ludmil Alexandrov. Find our transcript here: https://tinyurl.com/ScienceVsColonCancer In this episode, we cover: (00:00) Becca’s story (05:52) What the rise looks like (09:06) Is there something different about this cancer? (14:13) What symptoms to look out for (17:41) Why is this happening? (21:34) The hunt for explanations This episode was produced by Michelle Dang, with help from Rose Rimler, Meryl Horn and Ekedi Fausther-Keeys. Wendy Zukerman is our executive producer. We’re edited by Blythe Terrell. Fact checking by Erica Akiko-Howard. Mix and sound design by Bobby Lord and Bumi Hidaka. Music written by Bobby Lord, Bumi Hidaka, So Wylie, Emma Munger and Peter Leonard. And thank you to Prof. Caitlin Murphy. Science Vs is a Spotify Studios Original. Listen for free on Spotify or wherever you get your podcasts. Follow us and tap the bell for episode notifications. Learn more about your ad choices. Visit podcastchoices.com/adchoices

• 0:00Speaker 00

  Hi, I'm Michelle Dang and I'm filling in for Wendy Zukerman this week.

• 0:06Speaker 00

  And to start off today's episode, I want you to meet Becca Lynch. Becca lives in Colorado with her dog. She's 30 years old now, but throughout her twenties, she was leading a pretty hectic life.

• 0:18Speaker 01

  Kind of have always been pretty like full steam ahead. I've, I've never been like comfortable not being busy.

• 0:26Speaker 00

  She was getting her masters, growing her career and being super active.

• 0:31Speaker 01

  I go like climbing, I go to the gym. I was running a lot. I did a half marathon in 2024.

• 0:39Speaker 00

  Playing live music.

• 0:40Speaker 01

  Yeah, I have a little duo with a friend of mine that we play around town sometimes.

• 0:45Speaker 00

  But a couple of years ago, when Becca was 28, she noticed a change in her body, specifically in one area, the poo department. She noticed she was going number two more often, like five to six times a day. And it wasn't just that, there were a couple of weird things she saw in these frequent poos. And fair warning, we're about to get a bit detailed here. So for one thing, there was blood.

• 1:11Speaker 01

  It was like a dark, almost mucus-y, kind of thicker, bloody substance that was everywhere, like when I was going to the bathroom. And it was every single time.

• 1:23Speaker 00

  And the other thing she noticed is that her poo started to take on a different shape than usual.

• 1:29Speaker 01

  Like thinner size-wise, like pencil thin. I did the thing that everybody does, like I Googled it. Obviously I Googled all my symptoms.

• 1:36Speaker 00

  The results spit out quite a list of things it could be. Ulcerative colitis, IBS, Crohn's disease. Becca thought she should get it checked out, but didn't go in right away. And then one day she was scrolling on social media.

• 1:50Speaker 01

  Someone's video came across my feed, I think it was on Instagram, of someone talking about the exact same symptoms. She had said, like, for years, she thought she just had hemorrhoids, right?

• 2:01Speaker 00

  But this woman didn't have hemorrhoids. She had something a lot scarier: colon cancer. It was really advanced, stage four. And she was making these videos to tell people what to watch out for. And this was the push that Becca needed.

• 2:17Speaker 01

  I think it definitely solidified, like, okay, I should go to the doctor.

• 2:22Speaker 00

  Her doctor ordered a colonoscopy. So Becca eventually went through the prep, where you have to drink this gross liquid and poo a whole lot. And then she went in.

• 2:30Speaker 01

  I went there first thing in the morning. They just took me back and I met the doctor who was going to be doing it. You know, he was very, like, chipper and just like, yeah, we're going to figure out what's going on. He's like, could be a bunch of things. Like, it might just be hemorrhoids. Like, don't worry about it. You're going to be in and out of here in half an hour. Like, I'll see you in there. And then they rolled me back and that was it. I took a lovely nap.

• 2:55Speaker 00

  When Becca woke up, there was a nurse there. And immediately, Becca could tell something wasn't good. The nurse told her she was going to go out to the waiting room to get Becca's friend, who had come to pick her up.

• 3:06Speaker 01

  And she was just like, we're bringing your friend back because the doctor has to tell you something. And I was like, something bad? And she was like, yeah. And then she left. I waited there for 10 minutes. She left me with a bag of Goldfish and a Sprite. I sat there and waited. And eventually, my friend came back. And I was trying to keep it light, but at that point, I think I kind of knew. Like, I knew it wasn't going to be good, obviously. The doctor came back in and I just remember, like, it was more so his body language and, like, facial expressions that were more upsetting than like what he was saying because he had been this very, like, chipper, bubbly person before,

• 3:50Speaker 01

  like, the last time I'd see him. When he came back in, he was very sad. And he, like, sat at the foot of my bed and he just was like, we found a mass. It's five centimeters, about the size of a lemon.

• 4:03Speaker 00

  For Becca to officially get a diagnosis, the doctor told her she would need more scans and surgery.

• 4:09Speaker 01

  And he kind of ended it with being like, if it is cancer, which I'm certain that it is, you'll be the youngest person that I've ever seen with it.

• 4:19Speaker 00

  Becca was eventually diagnosed with stage three colon cancer at age 29. And this was really weird. She didn't have any of the usual risk factors. They ran genetic tests and didn't find any explanation. It all felt very strange.

• 4:35Speaker 01

  I knew that it was happening, but it really felt like I was watching it happen to someone else. But from that moment on, like, time kind of split and I just went into this kind of numb headspace of, all right, well, we have to deal with this. So, you know, we're going to deal with it and we'll figure it out.

• 4:53Speaker 00

  And Becca isn't the only person having to deal with this and figure it out. Around the world, more and more young adults are getting diagnosed with colorectal cancer. In the US, one in five people diagnosed with it are now younger than 55. That's a big increase from just a few decades ago, when only one in 10 colorectal cancers were being diagnosed in younger people. And that's not the only concerning thing. We're hearing that young adults are more likely to get diagnosed with a cancer that has already progressed pretty far, despite being otherwise healthy. So today on the show, we're going to talk about what exactly is going on here. Why are so many young people suddenly turning up with this type of cancer?

• 5:35Speaker 00

  And we'll hear more about what this has looked like for Becca. All that is coming up.

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• 7:01Speaker 00

  Welcome back. I'm producer Michelle Dang. Today on the show, we're looking at colorectal cancer. And with me is senior producer Rose Rimmler. Hey, Rose.

• 7:09Speaker 04

  Hi, Michelle.

• 7:10Speaker 00

  You know, Rose, I wanted to make this episode because I kept seeing scary headlines about this, about colorectal cancer increasing in young people. Have you been seeing these headlines too?

• 7:20Speaker 04

  Yes, I have. I've been seeing headlines about people getting colorectal cancer really young. And there's been some really high profile people that have gotten it and unfortunately actually died from it. So I'm thinking of the guy from Black Panther. That was a little while ago.

• 7:41Speaker 00

  Yeah, Chadwick Boseman.

• 7:43Speaker 04

  Yes.

• 7:44Speaker 00

  Yeah, he died from it in 2020 and he was only 43.

• 7:49Speaker 04

  That's awful.

• 7:50Speaker 00

  Yeah. And then just last month, the actor James Van Der Beek, he also died from colorectal cancer and he was 48.

• 7:58Speaker 04

  Right.

• 7:58Speaker 00

  Yeah. And by the way, this term colorectal cancer, it includes both colon cancer and rectal cancer, and sometimes also called bowel cancer.

• 8:08Speaker 04

  Okay, got it.

• 8:09Speaker 00

  And for years, doctors have thought of these cancers as cancers that older people get. In fact, Becca ran into this too.

• 8:17Speaker 01

  The hospital that I went to, they put me in this support group. It was like a Zoom support group for other people with GI cancers. And I joined it once and it was like me and then four women all in their like 70s and 80s. And they were all so kind and so lovely and they were very sweet to me. And like, I think one of them told me she was pissed off at God on my behalf, which I thought was very sweet.

• 8:42Speaker 00

  And the thing is, like, these cancers are still more common in older people.

• 8:46Speaker 04

  Mm-hmm.

• 8:46Speaker 00

  If you are under 50, the risk of getting this cancer is actually very low, way less than 1%.

• 8:52Speaker 04

  Hmm.

• 8:53Speaker 00

  But this increase is real, and it's freaking doctors out.

• 8:57Speaker 04

  So it's not, because sometimes you hear about a disease going up, and it turns out what's really happening is that doctors are getting better at catching it or diagnosing it or something. But in this case, it sounds like what you're saying, Michelle, is that, no, it's actually going up in young people.

• 9:13Speaker 00

  It's simply going up.

• 9:14Speaker 04

  Okay.

• 9:14Speaker 00

  There's more cases and there's more deaths.

• 9:17Speaker 04

  Okay.

• 9:17Speaker 00

  And doctors really caught on to this in the 90s, but the risk keeps increasing with each generation. Like, take a 40-year-old who's part of the millennial generation.

• 9:29Speaker 04

  My generation.

• 9:30Speaker 00

  Oh, your generation.

• 9:30Speaker 04

  Yep.

• 9:31Speaker 00

  And compare it to a 40-year-old who's part of the boomer generation.

• 9:35Speaker 04

  My generation spiritually.

• 9:37Speaker 00

  No, just kidding.

• 9:40Speaker 00

  Yeah, so that the 40-year-old millennial compared to a 40-year-old boomer, the millennial has a two to three times greater risk of developing colorectal cancer.

• 9:49Speaker 04

  So if you're 40 now, basically, your risk of colon cancer or colorectal cancer is higher than someone who was 40, you know, in the 80s or 90s?

• 9:59Speaker 00

  Yes, exactly.

• 10:00Speaker 04

  Geez, wow, that's real.

• 10:02Speaker 00

  Yeah.

• 10:02Speaker 04

  Yeah.

• 10:03Speaker 00

  And in the US, colorectal cancer was just declared the leading cause of cancer death in people under 50. It's led to nearly 4,000 deaths a year.

• 10:12Speaker 04

  Wow.

• 10:13Speaker 00

  So the thing I want to talk about next is the fact that when young people are diagnosed with this cancer, a lot of the time, it's really serious. You hear about people turning up with stage 3 or stage 4 cancer upon diagnosis. And studies have found that more than half of cases in early onset colorectal cancer are caught at these later stages.

• 10:35Speaker 04

  That sucks.

• 10:36Speaker 00

  Yeah, this makes this cancer sound really scary, because stage 4, for example, is when the cancer has already started to spread to different organs and other parts of the body. And if this is the case, it can be incredibly hard to cure. Your chance of dying within five years with colorectal cancer at stage four is about 80%.

• 10:57Speaker 04

  Wow, okay.

• 10:59Speaker 00

  So I wanted to find out, like, why is this?

• 11:01Speaker 04

  Yeah, what's going on here?

• 11:03Speaker 00

  So I called up Dr. Michael Foot. He's a gastrointestinal oncologist from Memorial Sloan-Kettering Cancer Center, and he's been watching what's going on here.

• 11:13Speaker 05

  We've been worried about this for a while, you know, over 10, 15 years. But it has reached a critical point in the last few years.

• 11:21Speaker 00

  And I wanted to know, is there something weird or creepy about the colorectal cancer that young people are getting? Like, is it moving faster or is it more aggressive? And Michael told me, no. Based on the studies we have, it looks like...

• 11:36Speaker 05

  Once they're diagnosed, the tumor behaves pretty similarly to a dozen adults. It responds to treatments in the same way. It can be just as aggressive.

• 11:43Speaker 00

  So why are young people showing up sicker? Michael says that young people's symptoms tend to be worse and the cancer spread further, not because of this, you know, idea that cancer is more aggressive, but because it's often getting caught a lot later than it is in older people.

• 12:01Speaker 05

  Not their fault, but they've, they've had a longer amount of time before they were diagnosed to catch this.

• 12:07Speaker 04

  Well, that makes sense to me, Michelle, because they're not routinely getting screened because they're too young to start getting screened with colonoscopies. So if there was a really young cancer, a really new cancer that wasn't causing any symptoms, there would be no way for them to know.

• 12:22Speaker 00

  Mm-hmm.

• 12:22Speaker 04

  But an older person who is getting screened, that would get, that would get picked up.

• 12:26Speaker 00

  Yeah, exactly. Like, the main reason that we find this cancer is with a colonoscopy. And we're just not usually giving those to young people unless something is wrong. And what is interesting is that in older people in the US, rates of this kind of cancer have actually been decreasing. Like, fewer people are getting it, fewer people are dying from it. And we think that's partly because we've gotten like pretty good at getting older people to go get colonoscopies regularly, where they can catch polyps in your gut that might turn into cancer.

• 12:58Speaker 04

  So the rates in older people are going down, but the rates in younger people are going up?

• 13:01Speaker 00

  Mm-hmm. Yeah. It's a dichotomy or discrepancy of like, why? Why is it going down for most of the people who are getting this?

• 13:10Speaker 04

  Right.

• 13:11Speaker 00

  But going up particularly for young people. And because of that, several years ago, doctors did decide to lower the recommended age for your first colonoscopy, for most people, from 50 to 45. There's actually people who say it should be even lower.

• 13:27Speaker 04

  Okay.

• 13:28Speaker 00

  Another piece of all of this is that for a lot of these young people, the symptoms can be easily confused for other things. Here's Michael again.

• 13:36Speaker 05

  I have a young person right now who's in their 30s, in their mid-30s, who had, who has an extremely aggressive cancer type that is very, very sick with metastases all over his bones.

• 13:50Speaker 00

  So this patient of Michael's has stage IV colon cancer. And what's weird is that Michael told me that their main symptom was back pain.

• 14:01Speaker 04

  Wow. Okay. I mean, that could be anything. Like, who doesn't have back pain? I could imagine you wouldn't go and get seen for that, you know? Certainly not by an oncologist. Who would think you'd have cancer just because your back hurts?

• 14:16Speaker 00

  Yeah, exactly. Here's Michael.

• 14:18Speaker 05

  Why are you having so much back pain? Why is this going on? No one would ever think about colon cancer. And then we found it. You know, we found it on a colonoscopy, and he's been ongoing with treatment.

• 14:29Speaker 00

  How did that patient react when they heard the news?

• 14:31Speaker 05

  They were absolutely terrified.

• 14:33Speaker 00

  Yeah. And the real reason this patient had the back pain was because the cancer had spread to his spine.

• 14:42Speaker 04

  Are they still with us?

• 14:43Speaker 00

  They are, yeah. And, you know, it's not great. They're treating the cancer, but it's aggressive. So basically, Michael and his team are just trying to make him feel better and give him as much time as they can.

• 14:54Speaker 04

  Less pain at least.

• 14:55Speaker 00

  Mm-hmm. Yeah. Now, Michael says that that back pain as the only symptom is extremely rare.

• 15:02Speaker 04

  Yeah, we're really freaking everyone out, Michelle, with that one, that story.

• 15:08Speaker 00

  I'm sorry, yeah. But, you know, changes in your stool are much more common.

• 15:12Speaker 04

  Okay.

• 15:12Speaker 00

  Like, blood in your stool and even abdominal pain. But even, even those symptoms are something that you could mistake for something else.

• 15:20Speaker 04

  Mm-hmm. Okay, actually, Michelle, I have a question for you. I have seen, like, a lot of chatter about this online and people talking about, like, symptoms to watch out for, but mostly they just say, like, look for any change in your bowel movements. It's like, get that checked out. And I find that really broad, like, not very helpful.

• 15:39Speaker 00

  I've seen those kinds of videos, too. And I'm curious, too, like, what, what exactly should you look for in your poo?

• 15:45Speaker 04

  Yeah.

• 15:46Speaker 00

  And so I asked Michael for you.

• 15:47Speaker 04

  Thank you.

• 15:48Speaker 00

  He told us that you shouldn't panic over a few weird poo days. But it's more like if you see changes or feel pain that lasts for weeks, then get it checked out. This includes things like diarrhea, constipation, and dark, tarry stools, or blood, like what Becca saw. And Michael has some more particular advice here, too.

• 16:09Speaker 05

  What we typically say with the stool is the stools become thinner. Meaning, you know, if there's a tumor there, it starts to press on the colon and, like a little, um, like a little cylinder, squeezes the stool into thinner shape, right? Because if there's less space in the tunnel, you have a smaller diameter there for the stool to go through, so it starts to get thinner.

• 16:29Speaker 00

  And while Becca, she had a lemon-sized tumor in her colon.

• 16:32Speaker 04

  Right, and she was talking about the skinny stools as well.

• 16:35Speaker 00

  Mm-hmm.

• 16:36Speaker 01

  Like, the mass was putting a lot of pressure on my colon, which was obviously making me having to go to the bathroom a lot more often, and the mass was also what was bleeding, so that's where the blood was coming from.

• 16:46Speaker 00

  That makes sense. But Becca's experience with her cancer speaks to another huge problem that doctors are seeing, because some of the stuff, like, like some of these poo symptoms, they often don't show up until the cancer is already pretty far along. When the tumor is already there and has had a chance to grow and cause problems.

• 17:05Speaker 01

  Which is still so crazy to me because when I think about like how long I was having symptoms, really, it was like noticeable symptoms were only a few months and it was still stage three.

• 17:15Speaker 04

  Thanks.

• 17:16Speaker 00

  And that plus the fact that some of the symptoms can be vague means that sometimes young people get misdiagnosed by doctors or even told they're too young to have colorectal cancer. So, you know, they don't get the tests that they need. Like in a big survey, four in 10 young people with colorectal cancer were initially told that they were too young to have it.

• 17:36Speaker 04

  Oh, wow. Okay.

• 17:37Speaker 00

  Overall, it can take like a really long time for young people to get diagnosed. And one study found that compared to older people, young people waited 40% longer to get a diagnosis from an oncologist.

• 17:50Speaker 05

  So by the time they get to us, it's further along in their disease course.

• 17:55Speaker 00

  So bottom line, it's not the disease itself that's doing something weird. It seems to be more like it's sneaking up on people and their doctors too and getting found after it's had a lot of time to get dangerous.

• 18:10Speaker 04

  So I guess that answers the question of why is it more likely to be caught at a later stage in younger people, but it doesn't answer the question of why are younger people getting it at all in such increasing numbers?

• 18:23Speaker 00

  Yes, that is the big question. And actually, we'll be looking at that next. Why is this all happening?

• 18:29Speaker 04

  Because I'm very impatient. I want to know now.

• 18:32Speaker 00

  Yes. So after the break, we'll take a look and talk to a scientist who's trying to find out.

• 18:36Speaker 04

  Okay, I can wait till after the break.

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• 20:18Speaker 00

  Welcome back. I'm Michelle Dang. We just learned that colorectal cancer is on the rise in young people. And the question now is, why? So, we're on the trail trying to figure it out. Like, what the hell is going on here? And I'm here with senior producer, Rose Romer Miller.

• 20:34Speaker 04

  Hello.

• 20:34Speaker 00

  Hey, Rose. So, yeah, one thing that comes up a lot is diet. People are eating a lot more ultra-processed food than they were before.

• 20:43Speaker 04

  Mm-hmm.

• 20:43Speaker 00

  And a big study just came out on this. It looked at this big dataset of almost 30,000 nurses and their health. I don't know if you're familiar, like, the nurses.

• 20:53Speaker 04

  The Nurses' Health Study?

• 20:54Speaker 00

  Yeah. Yeah, it's a group of nurses that have been followed for a long time and used in a bunch of studies.

• 21:01Speaker 04

  Mm-hmm.

• 21:02Speaker 00

  And what they found in this study is that people who ate the most ultra-processed food had a 45% higher chance of having polyps in their gut. Which, polyps can be harmless, but sometimes they do lead to cancer.

• 21:15Speaker 04

  Okay, so, people who ate more ultra-processed food had more polyps. Very suspicious. It's not super surprising because as we know from the ultra-processed foods episode, they tend to be associated with a lot of bad health outcomes. As we know from the fiber episode, if you're not eating a lot of vegetables, you need the fiber in vegetables. So that all makes sense that that would be bad for your gut and probably create an environment that could be helpful for growing cancer.

• 21:46Speaker 00

  Yeah, it's like we always come to that conclusion in science versus episodes.

• 21:51Speaker 04

  We do. It's like, eat vegetables. Okay. Over and over and over and over.

• 21:56Speaker 00

  Yeah. And that is because we do think there's some stuff that could be causing problems in ultra-processed foods, like preservatives. And then we also know that eating a lot of red meat, especially charred meat and processed meats are linked to some cancers, too.

• 22:11Speaker 04

  Yeah, actually, working on the ultra-processed food episode, I stopped buying like lunch meat.

• 22:16Speaker 00

  Oh, really?

• 22:17Speaker 04

  Sometimes I'd have like turkey, sliced turkey meat. Yeah, I don't eat that anymore.

• 22:20Speaker 00

  Sliced turkey meat?

• 22:21Speaker 04

  Yes, because it has nitrates and nitrites in it. And that has been associated with cancer.

• 22:27Speaker 00

  What about, what about cheese boards?

• 22:30Speaker 04

  Cheese boards? Does that count?

• 22:31Speaker 00

  Oh, sorry. I meant like prosciutto and salami.

• 22:36Speaker 04

  Oh, like charcuterie boards.

• 22:37Speaker 00

  Yeah, yeah, yeah, charcuterie boards.

• 22:39Speaker 04

  Once in a blue moon. I don't set out my spread of, you know, peeled grapes and charcuterie boards every night anymore.

• 22:47Speaker 00

  Yeah. Overall, it's probably a good idea to eat less of this stuff. And there are a few other risk factors that might be at play here, too. Things like obesity, lack of exercise, smoking, and alcohol. But I keep, I kept thinking like, there's gotta be something else going on here because I keep seeing and hearing stories of people with very healthy lives that eat great, exercise a bunch, yet still getting colorectal cancer at a very young age.

• 23:18Speaker 00

  Here's Dr. Michael Foote, who we heard from earlier.

• 23:21Speaker 05

  Most of the people that we see are actually pretty healthy. I have a patient who was a vegan, you know, who came in and, and she was like astounded. She had early-stage colon cancer, so we were able to remove it with surgery and then, and then treat her, and she's doing well. But, you know, she didn't really drink very much. She didn't smoke at all. So, you know, that's kind of the scary thing, I think, for all of us.

• 23:43Speaker 04

  Yeah. I'm thinking about Becca, who we met earlier. She seemed very healthy.

• 23:48Speaker 00

  Mm-hmm.

• 23:49Speaker 04

  And I don't know what she was eating, but it didn't sound like she was sitting down at McDonald's for every meal.

• 23:55Speaker 00

  Yeah, similarly, Becca told me she wasn't big on processed foods or alcohol.

• 24:00Speaker 01

  I don't know. Like I said, I was 28, I was healthy, like, I had just run a half marathon. I really wasn't thinking I might have cancer. My energy levels were fine. I was still go-go-go.

• 24:11Speaker 00

  So, what could be going on here? Lots of scientists are wondering if there's something else weird in the environment that people were exposed to that's maybe contributing to this, or perhaps changed up the gut microbiome. They're on the hunt for explanations, and so I want to talk about one of these ideas.

• 24:28Speaker 04

  Okay, great.

• 24:29Speaker 00

  One scientist we talked to is looking for clues inside the cancers themselves, like the actual DNA of these tumors. And his name is Professor Ludmila Alexandrov. And he's a cancer biologist at the University of California, San Diego.

• 24:42Speaker 08

  I actually specialize in cancer genetics and cancer genomics, and my focus is on understanding the processes that cause cancer.

• 24:51Speaker 00

  Several years ago, Ludmila and several colleagues started this big study looking at the genetics of colorectal cancer tumors. So what they did is they collected a bunch of tumors from people who had this kind of cancer. And they ended up with almost 1,000 tumors from across 11 different countries. Then they brought these samples back to the lab to test their genetic profiles. So Ludmila says inside a tumor, you can see these molecular fingerprints. These are made up of unique patterns of genetic mutations that can actually tell you a lot about that person's life.

• 25:26Speaker 08

  Molecular fingerprints, which we call mutational signatures, of what caused the tumor. So for example, if you smoke tobacco cigarettes, you're going to mutate in a very specific way. Many cells of your body, for example, the lung. And we can say, woo, this person smoked cigarettes. If you drink alcohol, you can see exactly the same thing.

• 25:45Speaker 04

  Wow, I didn't know scientists could do that. It's kind of cool.

• 25:48Speaker 00

  Yeah, I didn't either. I don't know what my cells could tell about me.

• 25:53Speaker 04

  I know, I was just thinking that.

• 25:55Speaker 00

  And a good chunk of these samples were tumors that came from younger people.

• 26:01Speaker 08

  About 15% of all the samples we collected were early onset cases, which is a very large number. You wouldn't expect that number. When we were designing this study, we expected less than 5%.

• 26:13Speaker 00

  Oh, so you weren't looking for that at the time?

• 26:15Speaker 08

  No, not at all.

• 26:16Speaker 00

  Now that he had this data with all these younger people in it, he could compare the tumors to see if there were genetic differences between the tumors in the younger and older people. To try and see, like, was there anything different that might help explain why the cancer is showing up more and more in young people? And he found that, yes, there was something different between these two groups. There was actually this particular set of fingerprints that stood out.

• 26:41Speaker 08

  And essentially, the difference was striking. If you look at individuals who were younger than 40, more than 50% of them had these very specific patterns of mutations.

• 26:53Speaker 00

  And when they looked into this specific pattern, it turned out that this type of mutation is often caused by certain bacteria that find their way into the gut.

• 27:01Speaker 04

  OK.

• 27:02Speaker 00

  And what can happen is that bacteria that get into our gut can release a toxin called colybackton. Rose, what do you know about colybackton?

• 27:11Speaker 04

  Colybackton, I don't know anything about it. Does it have something to do with cauliflower? Like...

• 27:16Speaker 00

  Cauliflower?

• 27:16Speaker 04

  Yeah.

• 27:17Speaker 00

  No, it does not have anything to do cauliflower.

• 27:20Speaker 04

  Okay, well, that was my best guess.

• 27:22Speaker 00

  Um, but it it's something that gets made by some bacteria. Like, for example, some types of E. coli make it.

• 27:29Speaker 04

  Oh, that's col- col- coli.

• 27:31Speaker 00

  E. coli. Yeah, it's more like a coli baccon than a collie cauliflower baccon.

• 27:37Speaker 04

  Coli baccon.

• 27:38Speaker 00

  Yeah, yeah. And one thing that coli baccon does is it can damage our DNA because of how it works as a toxin.

• 27:46Speaker 08

  I think of it as a weapon system, a weapon systems that uh uh that certain bacteria have, and they use it to protect themselves from other bacteria.

• 27:55Speaker 00

  So is this like um, is this like a weapon that the bacteria create for themselves?

• 27:59Speaker 08

  Yes, exactly.

• 28:01Speaker 04

  Hmm, so this is bacteria scooting around in our guts, pooting out this toxic substance.

• 28:08Speaker 00

  Yeah, I like I like that phrase, pooting, yeah. Um, if a bunch of these like bacteria get into your gut that make coli baccon, when the bacteria encounter other bacteria, they'll start pooting or shooting this stuff out in in all directions.

• 28:22Speaker 04

  It's like a little bacteria war, chemical warfare.

• 28:24Speaker 00

  Yeah, exactly. That's the theory. And some of that coli baccon could be slamming into cells in the wall of your gut. And that's where it can mess with your DNA.

• 28:34Speaker 04

  Oh, so the that coli baccon chemical warfare stuff damages the cells of the gut? And somehow that damages your DNA as well?

• 28:47Speaker 00

  Mm hmm, yeah. To break it down a bit more, what happens is coli baccon can hit a cell and then cause damage to the DNA in that cell. The cell will try to repair that damage, but sometimes it doesn't work. So you get mutations. And when that cell replicates, of course, those mutations replicate too.

• 29:07Speaker 04

  Mm hmm.

• 29:07Speaker 00

  And so sometimes mutations do nothing. Same thing with these coli baccon mutations. But other times, they might be the first step toward a cancerous tumor.

• 29:17Speaker 04

  Right.

• 29:18Speaker 00

  But what's really interesting here is that Ludmilla and his team were actually able to track down when these fingerprints were left behind, because they could put together this genetic tree and track mutations over time. At a basic level, how it works is the trunk of the tree shows you the DNA's original state. And then it hits a mutation, grows a new branch. Then another mutation, another branch. This sort of thing allowed Ludmille's team to put together an estimate of how old the person was when this mutation happened.

• 29:49Speaker 04

  Wow.

• 29:49Speaker 00

  Yeah.

• 29:50Speaker 04

  These are—this detective work is fascinating.

• 29:53Speaker 00

  Here's Ludmille again.

• 29:54Speaker 08

  We always saw that molecular fingerprint in the trunk of the tree. And what that means is that it happens very early.

• 30:03Speaker 00

  So studies have estimated that these colibactin mutations happened when people were kids, before they were 10 years old.

• 30:11Speaker 04

  Oh, before they even had the chance to start drinking or smoking or—

• 30:14Speaker 00

  Yeah, yeah.

• 30:16Speaker 04

  Wow, so it's—the seed is planted very early.

• 30:19Speaker 00

  Which is, you know, super surprising. And even more surprising, Ludmille says more recent work that's unpublished points to an even narrower window that it might have happened.

• 30:30Speaker 08

  That the more proper estimate is probably within the first two years of life.

• 30:34Speaker 04

  Oh, wow.

• 30:35Speaker 08

  So we think it's happening something in very, very early life. What we think happens is that when you have a young child, a year old, two years old, their microbiome and their immune system are getting formed, the microbiome in the colon. And if they get this infection, they get many, many mutations. And if you get many, many mutations at an early age, including some of the driving mutations that cause cancer, then if you get it at age two, well, now you're on the fast track for cancer. You get cancer in 20 or 30 years when you're a young adult.

• 31:14Speaker 04

  Two?

• 31:15Speaker 00

  Yeah, two.

• 31:16Speaker 04

  Oh, my god.

• 31:17Speaker 00

  This little baby.

• 31:18Speaker 04

  That's interesting. He says infection. Does he mean this bacteria that poots out the—

• 31:27Speaker 04

  What was it, colibactin?

• 31:29Speaker 00

  Mm-hmm.

• 31:29Speaker 04

  Is that the infection he's talking about?

• 31:31Speaker 00

  Yeah, when Ludmille says infection, he's talking about this idea that some kind of bacteria ended up in these people's guts as little kids.

• 31:39Speaker 04

  Okay.

• 31:39Speaker 00

  Maybe E. coli, which is pretty common in our guts, maybe something else. And they put out a bunch of this colibactin, and maybe that contributed to colorectal cancer developing years and years later.

• 31:52Speaker 04

  Wow.

• 31:53Speaker 00

  Yeah. Now, we do have to mention here that it's correlation, not causation. We can't test this by putting this bacteria into a bunch of babies, you know?

• 32:02Speaker 04

  Yeah.

• 32:02Speaker 00

  But we do have studies in some mice showing that when you put colibactin-making bacteria in their guts, they do get more tumors. So that's some more evidence of a potential link here.

• 32:15Speaker 04

  But let's assume that this is a real link. Do we have any idea, like, where this infection came from in the first place?

• 32:21Speaker 00

  So we don't exactly know. But Ludmille was like, the things that babies are exposed to that can affect the microbiome does change a lot from one generation to another. Like, younger people might have been exposed to more or different antibiotics. Maybe it's related to C-section rates or breastfeeding versus formula.

• 32:39Speaker 04

  Mm-hmm.

• 32:40Speaker 00

  Or maybe it's as simple as, like, a lot of us, like, everybody got exposed to a particular bacteria, and it caused an infection, and it just happened to do more damage if it happened to you as a baby.

• 32:51Speaker 08

  And I suspect that these microbes, some microbes that may be very harmless for us when we're adults are not that harmless for a one-year-old that's forming its immune system.

• 33:04Speaker 04

  Huh. Yeah. Like, it could have been a pandemic, a very quiet pandemic that some people are feeling the repercussions of now. Wow, that's fascinating.

• 33:13Speaker 00

  Yeah. And now, this is just one possible contributor.

• 33:18Speaker 04

  Uh-huh.

• 33:18Speaker 00

  Scientists are going full steam ahead to try to solve this mystery. Other suspects include other types of bacteria, maybe viruses, also chemicals in the environment or medications, like the antibiotics.

• 33:32Speaker 04

  That makes sense.

• 33:33Speaker 00

  So overall, we're getting a bunch of hints here, but no clear smoking gun. And this means that people like Becca don't have answers about where their cancer might have come from. But the good news is that Becca's doctors got her into treatment fast after she was diagnosed. So Becca had surgery. They took out the tumor, some lymph nodes, and more than a foot of her colon.

• 33:57Speaker 01

  Oh, man.

• 33:58Speaker 00

  And they got rid of all the cancer that they could find. But doctors also had her do chemotherapy last year. And after her last treatment, she celebrated with friends. Like, they had a picnic in the park. I asked her what they had.

• 34:11Speaker 01

  Oh, gosh. I think we just had a lot of cheese. It was really funny. I met with a dietitian early on during chemo, and they actually told me to, like, eat a lot of cheese.

• 34:20Speaker 00

  That's a nice blessing.

• 34:22Speaker 01

  Yeah, say less. Like, I'll have no problem eating a lot of cheese.

• 34:26Speaker 00

  But she's not totally out of the woods.

• 34:29Speaker 01

  I finished, in quotes, end of August. And so now people will ask, like, so you're done now, right? And it's like, yes and no.

• 34:38Speaker 00

  So Becca has to go back every three months for scans and blood work. And this part will last two years. There's a 25% chance of her cancer coming back during this time.

• 34:50Speaker 01

  Hmm. Um, so every three months, I get to be like a ball of anxiety, not know what's going to happen. But other than that, I'm just trying to, I don't know, focus on being here and feeling good right now.

• 35:07Speaker 00

  What do you wish you had known?

• 35:09Speaker 01

  I wish I had a good answer for this. I don't know. I, I think the biggest hurdle for me was, like, getting over this fear of being, like, thought of a certain way. Right? Like, my life was kind of always going 100 miles an hour. And I feel like I had built a big part of my personality around, like, being this very independent person. And nothing will humble you faster than this experience. And so I think it was, it was actually that first support group I went to with all of the, like, 70-year-old women. And one of them just told me, like, you have to learn how to let the love in. Like, you have to. Like, you can't do this by yourself. And so I think, I think I would tell myself, like, it's gonna be okay.

• 35:56Speaker 01

  And, you know, your friends are gonna show up in ways that you would never have expected. And like, that's what's, that's what's really gonna get you through it, is the people in your life.

• 36:08Speaker 00

  That's Science vs. All right. Thanks, Michelle. Thanks, Rose.

• 36:15Speaker 00

  Before we get to the citations, we've got a special sponsored segment for you with a very fun fact from the team. You're going to hear from Science vs. producer Aketi Foster Keys. Here it is.

• 36:28Speaker 09

  This segment is brought to you by the all-new Audi Q3. Here's an impressive fact. The Q3 features a roomy, comfortable, refreshed interior with a 12.8-inch touchscreen. Now, let's get to Dinner Party Genius.

• 36:49Speaker 09

  I'm Aketi Foster Keys, and this is our segment Dinner Party Genius, sponsored by Audi. I'm here with senior producer Merrill Horn. Hi, Merrill.

• 36:58Speaker 10

  Hey, Aketi.

• 36:59Speaker 09

  We're here to give you a fun science fact that will help you charm the crowd at your next party. Okay, Merrill. So, the fact that I want to talk to you about comes from research that I've been doing about running

• 37:12Speaker 10

  Huh.

• 37:12Speaker 09

  for an episode coming out soon. And it's about really long-distance running, like ultra-marathons.

• 37:18Speaker 10

  Hmm.

• 37:19Speaker 09

  Science is still figuring out what happens to our body when we run for super-long periods of time. And it turns out there might be something strange going on in our brains when we do this.

• 37:31Speaker 10

  Huh.

• 37:32Speaker 09

  So, there was a small study that looked at runners who competed in a really long race. Like, they went all the way from Italy to Norway.

• 37:42Speaker 10

  Whoa. How long is that?

• 37:45Speaker 09

  It's close to 2,800 miles and more than 4,000 kilometers.

• 37:51Speaker 10

  Oh, my God. Okay. So, this is like Forrest Gump-level running.

• 37:56Speaker 09

  Yeah, exactly.

• 37:58Speaker 10

  Jeez.

• 37:58Speaker 09

  And, of course, they got their brain scanned along the way.

• 38:02Speaker 10

  Oh, so they popped into a brain scan during the run? Got it.

• 38:05Speaker 09

  Right. And so, when scientists looked at the scans, they found something that they weren't expecting to see. They saw that during the race, these runners, their brains shrank a little.

• 38:16Speaker 10

  Ooh, that sounds bad.

• 38:19Speaker 09

  Yeah, it does sound pretty bad, right?

• 38:21Speaker 10

  Yeah, their brains shrank. Okay.

• 38:25Speaker 09

  Yeah. They lost, on average, about 6% of their green matter. But, the good news is, it wasn't permanent.

• 38:33Speaker 10

  Oh, okay. Well, that's good.

• 38:37Speaker 09

  The scientists also scanned people's brains after the race, about eight months afterwards. And their brains had gone back to normal, like nothing had ever happened.

• 38:46Speaker 10

  So if you ever run over 2,000 miles, your brain might shrink a little bit. But don't worry, it'll all bounce back when it's over. That's the fun fact?

• 38:55Speaker 09

  Yeah. It might shrink, but it might come back too. It will come back.

• 39:00Speaker 10

  Okay.

• 39:02Speaker 09

  Do you feel prepared for your next dinner party?

• 39:04Speaker 10

  Oh, yes, yes. I am so prepared with this fun fact. Yeah, I am ready for the party.

• 39:13Speaker 09

  Okay, thanks, Meryl.

• 39:15Speaker 10

  Thanks, Akedi.

• 39:17Speaker 09

  That segment was brought to you by the all-new Audi Q3. Here are a few more fun facts. The all-new Audi Q3 features more power and more space than ever before. Plus, Quattro all-wheel drive gets you there with confidence. It's built to impress, kind of like you at your next dinner party. Say yes to the all-new Audi Q3. Made for the yes life. Learn more at AudiUSA.com.

• 39:47Speaker 00

  Okay, Rose, we're back. Time for citations. Can I tell you how many we have in this week's episode?

• 39:52Speaker 04

  You sure can.

• 39:53Speaker 00

  There are 72 citations. And where can people find them, Rose?

• 39:59Speaker 04

  You can find them in the transcripts of the episode. And you can find that by clicking a link in the show notes.

• 40:05Speaker 00

  Cool. Thanks, Rose.

• 40:06Speaker 04

  Thanks, Michelle.

• 40:13Speaker 00

  This episode was produced by me, Michelle Dang, with help from Rose Rimler, Meryl Horn, and Akedi Foster Keys. Wendy Zukerman is our executive producer. We're edited by Blythe Terrell. Fact checking by Erica Akiko Howard. Mix and sound design by Bobby Lord and Bumi Hidaka. Music written by Bobby Lord, Bumi Hidaka, So Wiley, Emma Munger, and Peter Leonard. And thank you to Professor Caitlin Murphy. Science vs. is a Spotify Studios original. Listen for free on Spotify or wherever you get your podcasts. Follow us and tap the bell for episode notifications. We'll thank you soon.