Workouts Help to Treat Cancer and Improve Survival
To improve the quality of life of people with cancer, oncologists recommend regular exercise. Staying fit can make patients feel better and function better. But exercise itself has never been considered a formal treatment for the disease.
“The medical community thought you needed biomedical interventions (surgery, radiation, medications) to treat cancer,” says Kerry Courneya, a professor of kinesiology at the University of Alberta who studies physical activity and cancer.
This way of thinking is changing. This year, strong evidence showed that exercise increases survival time and reduces the risk of recurrence for several types of cancer. Such benefits are usually attributed to medicine or surgery. But “exercise treats cancer as well, if not better, than some of the current drugs we offer our patients,” says Courneya, who led the first large randomized controlled trial of the effects of exercise on cancer progression. It was published in July in the New England Journal of Medicine and involved more than 800 colon cancer patients. Participants with high-risk stage 3 and stage 2 cancer were assigned to a structured exercise program in addition to their oncology care. Over a 10-year follow-up period, these individuals had a 28% lower risk of cancer recurrence, new cancers, or death than similar patients who received only educational materials on physical activity.
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These findings drew a standing ovation when they were presented to the American Society of Clinical Oncology at a meeting in June. This is not the only good news in the field. For 10 different types of cancer – breast, prostate, colon, lung, oral, endometrial, respiratory, rectal, bladder and kidney – a 2025 longitudinal study of more than 90,000 cancer survivors in the United States found that people survived longer if they engaged in moderate to vigorous physical activity after their diagnosis. Even small amounts of exercise made a difference, but 150 to 300 minutes per week of moderate-intensity activity, such as brisk walking, was the most effective intervention.
There was a slight additional benefit with higher activity levels. (Overall, the magnitude of the effect varied across different cancer types.) Randomized trials of exercise interventions are currently underway for breast, ovarian, esophageal, and lung cancer, among others.
There had been indications that exercise provided this type of help. For example, a 2011 study showed that men with prostate cancer who engaged in at least three hours of vigorous exercise per week had a reduced risk of death from the disease. Other studies have found similar results for breast and colon cancer.
Strong evidence has emerged that exercise extends survival time and reduces the risk of recurrence for several types of cancer.
What is exercise doing inside the body that has this therapeutic effect? Exercise triggers so many biological changes at once that it’s hard to say for sure. But there are several possibilities, and they probably work in combination.
A reduction in overall inflammation is likely a factor, says epidemiologist Stacey Kenfield of the University of California, San Francisco. Another important benefit of exercise is that it makes the hormone insulin bind more easily to cells, providing them with new energy. When insulin is not able to bind, the body begins to produce more of it. This is bad because cancer cells can use insulin to grow and divide more quickly.
Myokines, which are proteins released by muscle tissue, could also play an important role. In the laboratory, serum containing high amounts of myokines reduced the growth of prostate cancer cell lines. In studies of men with prostate cancer published in 2022, Kenfield and colleagues found that myokines levels were higher just after half an hour of training with vigorous exercise – and in men who had been exercising for six months – compared to levels in a group of cancer patients who did not exercise.
The workouts also seem to engage parts of the immune system that control cancer, says immunologist Per Thor Straten of the Center for Cancer Immunotherapy in Denmark. In mice, he showed that voluntary exercise leads to an influx of immune cells into tumors, as well as a more than 60 percent reduction in tumor incidence and growth. During exercise, Straten explains, the number of immune system components called natural killer cells and T cells increases significantly. “They are very effective killers of cancer cells,” he says.
Straten and his colleagues are working on an ongoing randomized trial in lung cancer patients, and they hope it will show that this immune response occurs in humans. Supporting findings have emerged in early data from a 2025 study in the United Kingdom. In a small randomized trial of esophageal cancer patients, half of the participants did structured exercise during their chemotherapy, and half were in a group without a structured program. Tumors from patients who exercised appeared to contain more T cells and natural killer cells.
Experts say that regularity and intensity of exercise are important. “You have to get your heart pumping” to boost the immune system, Straten says. In the colon cancer study, participants chose their type of exercise but received support such as supervised workouts and counseling on behavior change. This helped them stick with the program, Courneya says. “You can’t just advise people to exercise more and expect them to do it,” he explains.
Today, many cancer centers are considering how to provide this type of support in addition to their medical offerings. If they don’t, experts say, the centers won’t be able to offer a new standard of care.
This article was made possible thanks to the support of Yakult and produced independently by Scientific AmericanThe editorial board of.
