New evidence shows us just how directly exercise helps the body fight cancer

W

e’re not learning anything new when we hear that exercise is great for you. You can probably rattle off the benefits in your sleep: improves health, cognition, mood, extends life. Experts have been telling us this for years.

But now, a newly published study published in the New England Journal of Medicine shows that regular physical activity extends the lives of colon cancer survivors.

What makes this study different is the study structure. In the past, similar research linking exercise and cancer outcomes were conducted through observational studies. Researchers observed outcomes and questioned participants about past habits. This type of study can suggest correlations and associations, but not definite cause and effect.

This new study was a randomized trial. Randomized trials can more definitively identify causation. Participants are randomly assigned to groups and researchers can balance outside factors accordingly. This is the first study that has looked at how exercise impacts cancer survival and recurrence rates.

The study followed close to 900 patients across 55 different health centers in five countries. All had undergone surgery and chemotherapy between 2004 and 2024. All had stage III or high-risk stage II colon cancer.

Study participants were split into two groups — a health education group and an exercise group. The health education group was provided with materials and information on nutrition and physical activity.

The exercise group was assigned a health coach. People in the exercise group were asked to choose a form of aerobic activity. Choices included biking, jogging, swimming, and kayaking. Most opted for a brisk walk. The exercise group was told to engage in aerobic activity three to four times per week for 45-60 minutes per session.

For the first six months, the coach checked in weekly with each participant. After that, it was once a month.

The study found that the survival rate was significantly higher for those colon cancer survivors who engaged in a regular program of exercise. Overall, when comparing the two groups, researchers found a much lower cancer recurrence rate in the exercise group when compared to the health education group. After five years, the disease-free rate was 80.3% for the exercise group compared to 73.9% for the health education group. After eight years, the survival rate for the exercise group was 90% compared to 83% for the health education group.

“We now have definitive evidence that exercise is not just an intervention for quality of life and fitness,” Dr. Christopher Booth, a professor of oncology at Queen’s University in Canada and lead researcher in the study, told The New York Times. “This is an intervention that improves survival and should be standard of care.”

Observational studies across a range of cancers have suggested the same thing — that exercise extends the lifespan of survivors, and it’s safe to assume exercise is beneficial to any cancer survivor, as well as a form of cancer prevention.

While the impact of exercise is clear from the studies, the real-life influence would depend on an individual’s motivation to exercise. In the study, most of the participants were younger and healthier than the typical cancer patient, and possibly more motivated to exercise.

The question that hasn’t yet been answered is why exercise has such an impact on survival rates. While scientists can’t point definitively to a specific answer, there is enough evidence on the power of exercise to venture a guess. Exercise impacts growth hormones and inflammation levels. It encourages a series of chemical reactions in the body, which seem to act as cancer prevention. An inactive lifestyle can lead to cell inflammation, which, in turn, can cause cells to mutate. But being physically active is beneficial to the immune system and reduces cell inflammation, suppressing cell mutation.

(Originally featured in Family First, Issue 978)