Transcript

Michelle Dang (0:00)

Hi, I'm Michelle Dang, and I'm filling in for Wendy Zuckerman this week. 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 20s, she was leading a pretty hectic life.

Becca Lynch (0:18)

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

Michelle Dang (0:26)

She was getting her master's, growing her career, and being super active.

Becca Lynch (0:31)

I go, like, climbing. I go to the gym. I was running a lot. I did a Half Marathon in 2024, playing live music. Yeah, I have a little duo with a friend of mine that we play around town sometimes.

Michelle Dang (0:45)

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 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.

Becca Lynch (1:11)

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

Michelle Dang (1:23)

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

Becca Lynch (1:29)

Like, thinner. Size wise, like, pencil thin. I did the thing that everybody does. Like, I googled it, obviously. I googled all my symptoms.

Michelle Dang (1:36)

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.

Becca Lynch (1:50)

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?

Michelle Dang (2:01)

But this woman didn't have hemorrhoids. She had something a lot. 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.

Summary

Science Vs – "Colon Cancer: Should Young People Worry?"

Host: Michelle Dang (with Rose Rimler)
Date: March 19, 2026
Podcast: Science Vs (Spotify Studios)

Episode Overview

In this episode, guest host Michelle Dang investigates the alarming rise in colon and rectal cancer diagnoses among young adults. Through personal stories, expert interviews, and the latest scientific research, the team explores why more young people are being affected, what symptoms to watch for, the potential causes behind this uptick, and what we still don’t understand about early-onset colorectal cancer.

Key Discussion Points & Insights

Becca’s Story: A Young, Active Patient Diagnosed With Colon Cancer

[00:00–05:50]
- Introduction to Becca Lynch, who was 28 when she began experiencing abnormal bowel habits, including frequent stools, blood, and "pencil-thin" shape.
- Initial hesitation to seek medical care, eventually prompted by social media content about colon cancer symptoms.
- Upon colonoscopy, she learns she has a 5cm (lemon-sized) tumor. Diagnosed with stage 3 colon cancer at 29, despite lacking risk factors or family history.
- Notable Quote:
  - “If it is cancer, which I’m certain that it is, you’ll be the youngest person I’ve ever seen with it.” — Becca's doctor ([04:09])
- Emotional shock and rapid transition to coping and treatment.

The Broader Trend: Colon Cancer Rising in Young Adults

[06:58–10:55]
- Statistical rise: 1 in 5 colorectal cancer diagnoses now occur in people under 55; previously, it was 1 in 10.
- High-profile cases noted, e.g., Chadwick Boseman (died at 43) and James Van Der Beek (died at 48).
- The disease is still uncommon in the young (under 1% risk if <50), but the increase is real.
- Millennials (now 40) have 2–3 times the risk of colon cancer as 40-year-olds from earlier generations.
[10:00–13:00]
- Colorectal cancer recently became the leading cause of cancer death in Americans under 50.
- Young adults are often diagnosed at later, more dangerous stages (stage 3 or 4), making it harder to treat.
- Quote:
  - "Your chance of dying within five years with colorectal cancer at stage four is about 80%." — Michelle Dang ([10:54])
- Late diagnoses are not because tumors are more aggressive, but because they’re often caught later in younger people.

Why the Late Diagnoses in Young Adults?

[13:00–17:00]
- Young adults typically aren't screened (colonoscopies are generally offered starting at age 45).
- Symptoms (like back pain, blood in stool, thin stools) can be missed or attributed to less serious conditions.
- Expert Input:
  - "Once they're diagnosed, the tumor behaves pretty similarly to a dozen adults... Not their fault, but they've had a longer amount of time before they were diagnosed to catch this." — Dr. Michael Foote ([11:33], [11:59])
- Many young patients are initially told they're too young to have cancer; diagnosis is often delayed by 40% compared to older adults.
- Studies show young adults’ first symptoms are frequently mistaken for IBS, hemorrhoids, etc.

What Symptoms Should Young People Watch For?

[15:43–17:03]
- Don’t panic over short-term changes in bowel movements, but persistent symptoms (>2 weeks) are cause for concern:
  - Changes in stool frequency/shape (especially “pencil-thin” stools)
  - Blood in stool (especially dark, tarry, or mucusy blood)
  - Persistent abdominal pain
  - Unexplained back pain (rare, but can be a sign if cancer metastasized)
- Quote:
  - "If there's a tumor there, it starts to press on the colon... Like a little cylinder squeezes the stool into a thinner shape." — Dr. Michael Foote ([16:07])

What's Driving the Rise? Investigating the Causes

[21:48–35:04]

The Usual Suspects: Environment and Diet

Ultra-Processed Foods:
- Large study of nurses found 45% higher rates of polyps (which can become cancerous) in those who ate the most ultra-processed foods. ([22:26])
- Red and processed meats, preservatives, and lack of fiber are also implicated.
Other Risk Factors:
- Obesity, inactivity, smoking, and alcohol are known contributors.
But: Even very healthy young adults sometimes get the disease, suggesting more factors are at play.
- Expert Input:
  - "Most of the people that we see are actually pretty healthy... that’s kind of the scary thing, I think, for all of us." — Dr. Michael Foote ([24:51])
  - Personal story: Patient who was vegan, nonsmoker, and rarely drank alcohol still got colon cancer.

New Lead: The Colibactin Hypothesis

[25:58–35:04]

Genetic Detective Work:
- Prof. Lyudmil Alexandrov analyzed genetic "fingerprints" (mutational signatures) in tumors of young and old patients.
- Found 50%+ of young patients' tumors showed a unique pattern linked to bacterial toxins, particularly colibactin (produced by some E. coli).
- Quote:
  - "Essentially, the difference was striking. If you look at individuals who are younger than 40, more than 50% of them had these very specific patterns of mutations." — Prof. Lyudmil Alexandrov ([28:12])
- Colibactin is a bacterial toxin (produced by certain gut bacteria) that can mutate gut cells' DNA.
When Does Exposure Happen?
- Most colibactin-linked mutations occurred very early in life — often before age 10, possibly in the first two years. ([32:05])
- The gut microbiome and immune system are especially vulnerable in young children.
- Possibilities: changes in antibiotic use, birth practices (C-section rates), exposure to certain bacteria in early childhood.
- Quote:
  - “We think it’s happening something in very, very early life...when you have a young child...their microbiome and their immune system are getting formed...and if they get this infection, they get many, many mutations.” — Prof. Lyudmil Alexandrov ([32:05])
Caveats:
- The link is “correlation, not causation”—it can’t be proven directly in humans.
- Other suspects may include other microbes, viruses, antibiotics, or environmental exposures ([34:44]).

Becca’s Prognosis and Reflections on Healing

[35:03–37:39]

Becca underwent surgery (removal of tumor, lymph nodes, 1 foot of colon) and chemotherapy.
Celebrated the end of chemo with friends—with, humorously, lots of cheese on advice from her treatment dietitian.
Ongoing surveillance: scans and bloodwork every 3 months for 2 years with a 25% recurrence risk.
Notable Quote:
- “I think I would tell myself, it’s going to be okay and, you know, your friends are going to show up in ways that you would never have expected. And like, that’s what’s really going to get you through it is the people in your life.” — Becca Lynch ([37:35])

Memorable Quotes & Moments

“We found a mass. It's 5 cm, about the size of a lemon.” — Becca Lynch recounting her doctor’s diagnosis ([04:03])
“Colorectal cancer was just declared the leading cause of cancer death in people under 50.” — Michelle Dang ([10:00])
“Your chance of dying within five years with colorectal cancer at stage four is about 80%.” — Michelle Dang ([10:54])
“If you see changes or feel pain that lasts for weeks, then get it checked out.” — Dr. Michael Foote ([15:45])
"It's sneaking up on people and their doctors too, and getting found after it's had a lot of time to get dangerous." — Michelle Dang ([17:52])
“What we think happens is that when you have a young child... their microbiome and immune system are getting formed... if they get this infection, they get many, many mutations...” — Prof. Lyudmil Alexandrov ([32:05])
"You have to learn how to let the love in... you can’t do this by yourself... your friends are going to show up in ways that you would never have expected." — Becca Lynch ([37:35])

Timestamps of Important Segments

[00:00–05:50] — Becca’s personal journey and diagnosis story
[06:58–10:55] — Exploring the trend: colon cancer increasing in the young
[13:00–17:00] — Why are young adults diagnosed so late? Symptoms and screenings
[21:48–25:14] — Environmental factors, diet, and “standard” risks
[25:58–35:04] — New genetic and microbiome evidence (colibactin hypothesis)
[35:03–37:39] — Becca’s treatment, recovery, and life lessons

Final Thoughts

This episode makes clear that while lifestyle factors like diet and exercise do matter, they don't explain the entire increase in young-onset colorectal cancer. There is emerging evidence that early-life exposures to certain gut bacteria (and their DNA-damaging toxins) could set the stage for cancer decades later. But much remains uncertain—and researchers are urgently seeking answers.

Through Becca’s powerful story and the voices of scientists, "Science Vs" gives listeners a nuanced, science-driven understanding of this worrying – but still rare – trend.

For more information and citations, see the transcript in the show notes.