We talk a lot about exercise in the cancer clinic. Alongside nutrition, sleep, and a positive mindset, it’s one of the pillars of good health I try to emphasize with every patient I see. These aren’t just nice-to-haves—they are key ingredients in improving outcomes not only for cancer survivors but for all of us.
A new study recently published in The New England Journal of Medicine (June 1, 2025) has me thinking even more deeply about this. The study—called CHALLENGE—looked at the role of structured exercise after surgery and adjuvant chemotherapy in patients with stage II or III colon cancer. What makes it truly fascinating is that it didn’t just show that exercise is good for general health. It showed that exercise reduces cancer recurrence and improves survival—in a large, randomized, phase 3 trial.
Honestly, if this had been a drug, every pharmaceutical company in the world would be shouting it from the rooftops. It would be a billion-dollar industry overnight. But because it’s “just” exercise—free, simple, but often hard to do—the news hasn’t made the same splash. And that’s a shame, because the implications are profound.
What the CHALLENGE Study Showed
The CHALLENGE trial enrolled 889 patients across 55 centers in Canada and Australia (yes, apparently they decided not to even try enrolling us Americans with our, let’s say, variable exercise habits). These were patients who had completed surgery and chemotherapy for high-risk stage II or stage III (90%) colon cancer and were otherwise relatively healthy.
Patients were randomized into two groups:
- Structured Exercise & Behavioral Support Group: This wasn’t just “go exercise” advice. It involved three years of health education, behavior change support, and supervised exercise. They used 17 evidence-based techniques to help patients stick with it, with multiple phases that gradually reduced supervision but maintained accountability.
- Education-Only Group: Patients received educational materials alone.
The results were remarkable:
- A 28% reduction in cancer recurrence in the exercise group.
- A 37% reduction in overall mortality.
- Fewer new primary cancers, including breast, prostate, and additional colon cancers.
Patients who exercised also showed fewer distant metastases, including fewer liver metastases—a common site for colon cancer spread.
This isn’t just about colon cancer. It’s about how exercise improves immune surveillance, reduces inflammation, improves insulin sensitivity, and creates a less hospitable environment for cancer cells to grow and spread. We’ve known this from retrospective data for years, but to have it confirmed in a randomized trial is something new, exciting, and provocative.
The Universal Power of Exercise
In his book Outlive, Dr. Peter Attia talks about the “Four Horsemen” of chronic disease: cardiovascular disease, cancer, neurodegenerative disease, and metabolic dysfunction. Exercise is one of the very few interventions (along with proper nutrition, sleep, mental health) that reduces risk across all four. We’ve been saying this for decades, but studies like CHALLENGE give us the hard evidence.
And yet, exercise is still one of the hardest things for many of us to do—including me.
My Orange Theory Story (Or: Why I Still Drag Myself to Exercise)
I’ve always considered myself pretty athletic. I’ve played basketball, I’ve run, I’ve kept active. But life happens—work, marriage, kids—and suddenly, you’re looking at yourself wondering where that “dad bod” came from.
A few years ago, I joined Orange Theory. If you’re not familiar, it’s one of those high-intensity, structured workout programs where they push you to get your heart rate into a target zone through a mix of strength and cardio. I’ll be honest: I hated it at first. It was way more than I was doing on my own at the gym. And when I realized I couldn’t cancel my membership for two months, I begrudgingly decided to stick with it.
Sixteen classes later, I couldn’t believe the difference. It wasn’t just physical—it was mental clarity, energy, mood. I realized that sometimes you have to “donate your body” to a process that’s bigger than your short-term comfort.
Exercise, I’ve come to think, is like brushing your teeth. You don’t do it because you love it. You do it because you value the outcome. And while the first few steps—getting off the couch, lacing up your shoes, walking into the gym—are always the hardest, I’ve never once regretted a workout when it’s done.
The Takeaway: Structured Exercise Works—For All of Us
The CHALLENGE study isn’t just for colon cancer survivors. Its lessons apply to everyone. Exercise isn’t just for weight loss or aesthetics. It’s a real, evidence-based intervention that reduces the risk of cancer recurrence, heart disease, diabetes, neurodegenerative disease, and more.
If exercise were a pill, every one of us would be on it.
But because it takes effort—and behavior change—it often falls by the wayside. Even for oncologists like me who know better. But this study is a reminder that it’s worth the effort. Not just to live longer, but to live better—to have a longer “healthspan,” where we remain active, independent, and engaged well into our later years.
So maybe we all need to stop thinking about exercise as something we should do, and start thinking about it as something we need to do—like brushing our teeth, like taking our medicine, like showing up for our own future selves.
And if you’re like me, sometimes it starts with just telling yourself: Let’s just go for a walk.
About the author
Dr. Sajeve Thomas is a distinguished medical professional and a compassionate guide in the field of oncology. With over a decade of dedicated experience as a board-certified medical oncologist/internal medicine specialist, Dr. Thomas has become a trusted expert in the treatment of melanoma, sarcoma, and gastrointestinal conditions. He brings a wealth of expertise to the complex and challenging world of oncology.
Disclosures:
Dr. Thomas serves as a speaker for Bristol Myers Squibb (BMS), Merck, Ipsen, Natera, Immunocore, Pfizer, and SpringWorks. He also receives industry grants in support of numerous clinical trials.