What if one of the most powerful ways to slow cancer’s advance was already inside us—hidden within our own metabolism? A groundbreaking study from Yale University has explored how physical activity reshapes the body’s energy balance and what that means for tumor growth.
Living well—eating healthy, staying active, and maintaining good habits—has long been known to lower the risk of cancer and help people recover better when illness strikes. But what scientists haven’t fully understood is how movement can actually slow down a tumor. A new study from the Yale School of Medicine, published in Pnas, finally brings that mystery into focus.
When muscles “starve” the tumor
Led by Rachel Perry from Yale’s Department of Cellular and Molecular Physiology, researchers studied 18 mice implanted with breast cancer cells. Some were made obese through diet, a condition known to speed up tumor progression. Half of them had access to a running wheel, allowing them to exercise freely.
The findings were striking: among obese mice that ran, tumors were about 60 percent smaller than in their sedentary counterparts. Even compared to non-obese sedentary mice, the active ones had slightly smaller tumors.
After 30 minutes of exercise, scientists measured a sharp rise in glucose use by skeletal and cardiac muscles—and a drop in glucose absorbed by tumors. In simple terms, when muscles are active, they grab the glucose first, leaving cancer cells with less fuel to grow.
The team also found changes in 417 genes linked to energy metabolism. One key factor stood out: reduced expression of mTOR, a protein known to trigger cell growth. “Lowering mTOR levels in tumor cells suggests the tumor enters a state less favorable to proliferation,” Perry explained.
Three oncologists from the Curie Institute answer this question about adapted physical activity in oncology. © Curie Institute
Exercise as a genuine therapeutic tool
The study reinforces a growing belief among oncologists: exercise isn’t just a lifestyle habit—it’s a real therapeutic ally.
Rob Newton, an expert in exercise oncology at Edith Cowan University in Australia, put it simply: “If you have more muscle mass and activate it regularly, the effect on glucose absorption becomes even stronger.”
The researchers stress that the mice weren’t marathoners. They ran voluntarily, at their own pace. “It wasn’t about pushing limits—it was about letting the body move as it needed.” This suggests that even moderate, consistent activity could spark similar metabolic effects in humans.
While clinical trials will be the next step, the scientists say there’s “little reason to think the same results wouldn’t apply to humans.”
In the end, the study highlights how movement influences the body on several levels at once:
• the immune system;
• the gut microbiome;
• inflammation;
• and, now, direct metabolic competition with tumors.
As Perry notes, “These metabolic shifts could be the missing link that connects all these mechanisms.” Newton adds, “Physical activity should be viewed as a complementary cancer therapy—not just a lifestyle choice.”
Christelle Cherrier
Web editor
Passionate about words and driven by curiosity, I traded my career as a market research analyst for the sharpened pen of a web writer. For five years, I’ve specialized in health and wellness, delivering clear and insightful content. I’m endlessly fascinated by everything human—from the workings of the body to the mysteries of the mind. My goal? Making complex topics accessible, informative, and engaging—no prescription required!