Exercise and Cancer: From Easing Side Effects to Extending Survival
Doctors already urge people with cancer to exercise, mostly to fight fatigue and help them stay strong through treatment. Whether a workout plan can also help them live longer has been much harder to prove.
A review of 21 clinical trials found that cancer patients assigned to structured exercise programs were less likely to die during follow-up and less likely to see their cancer come back. The authors wrote that the results make a case for including exercise as part of cancer treatment itself, not only a way to cope with side effects.
Why the Team Used Trials Instead of Observational Studies
Most of the evidence that exercise helps people survive cancer comes from following large groups over time and asking how active they are. Those studies have repeatedly linked more activity after a diagnosis with fewer deaths.
But people who exercise may already be healthier, and people who are very sick may stop exercising. So those studies can't show which causes which. In a clinical trial, chance decides who gets the exercise program and who doesn't, which takes that problem away.
The team searched six research databases through December 20, 2025, and screened more than 12,000 records. They kept only trials in which adults with confirmed cancer were randomly assigned to supervised exercise or to a comparison group. The exercise was aerobic, strength training, or both. The comparison was usual care, health education, or drug treatment alone.
Breast cancer dominated, with 11 trials and about three-quarters of all participants. Colorectal and pancreatic cancer came next. The average participant was about 54 years old, and the trials followed people for just over five years.
Exercise Linked to Longer Survival
Across 11 trials with 3,828 people, those in exercise programs had a 23 percent lower risk of dying during follow-up than those who weren't.
Doctors also track disease-free survival, the time before the cancer returns, a new cancer appears, or the person dies. That risk was 17 percent lower in seven trials with 5,077 people.
The team found the same pattern in two more measures. Deaths from any cause were 18 percent lower across 13 trials, and deaths from cancer itself were 26 percent lower across six.
Taking out any single trial didn't change that picture. The authors rated their confidence in these main findings as moderate, mostly because the trials together still weren't large enough. A statistical check also hinted that small trials with strong results might be overrepresented. Adjusting for that shrank the survival benefit to 17 percent, right at the edge of what chance alone could explain.
Not everything improved. Exercise didn't delay the point when a tumor started growing again, and it didn't raise the chance that chemotherapy before surgery left no invasive cancer behind. Only five small trials measured each of those.
People Who Stuck With It Did Better
Between trials, there was a large variation in how closely people followed their exercise plans. In CHALLENGE, a colon cancer trial included in the analysis, participants mostly stuck to the program. Adherence in the other trials was far less consistent.
So the team ran a separate, exploratory analysis limited to people or trials that completed at least 70 percent of the program. Using these results, those in exercise programs had a 28 percent lower risk of dying during follow-up, and a 29 percent lower risk of recurrence or death.
That doesn't prove more exercise brings more benefit. People who stick with a program may differ in health and habits from people who drop out, the authors wrote. Still, they said programs should be built to keep patients going, with close supervision and workouts adjusted to how each person feels during treatment.
Aerobic Workouts Showed the Clearest Link
Programs built on aerobic exercise alone were linked to a 29 percent lower risk of death. Programs combining aerobic exercise with strength training were linked to a 25 percent lower risk.
Strength training by itself showed no clear link to survival. But only one trial, with 129 people, tested it alone, so the authors wrote that the result should be read with caution.
The team saw similar estimates in early and advanced cancer. The one for advanced disease was less certain because those trials were smaller and recorded fewer deaths, not because the benefit looked smaller. None of the gaps between these groups was large enough to be attributed to anything other than chance.
How Exercise Might Fight Cancer
The trials weren't designed to show why exercise helped. The authors pointed to possibilities from earlier research.
One is that exercise may draw cancer-fighting immune cells into tumors and improve blood flow inside them. This may help drugs reach their target. "Aerobic exercise drives systemic cardiovascular conditioning, immune cell mobilization and normalization of tumor perfusion, mechanisms directly relevant to systemic tumor control," the authors wrote.
Exercise can also modestly lower estrogen and androgens, hormones that are tied to breast cancer risk. That matters, given how many women were in these trials. Working muscles take up more sugar from the blood, which may leave less to fuel tumor cells. Exercise may also boost the enzymes that repair damaged DNA.
What Remains Unknown
Several things could have blurred the results. Many people in the comparison groups adopted healthier habits on their own, and in one lymphoma trial 42 percent of them switched to supervised exercise. The programs varied widely in type, intensity, and length.
People who volunteer for these trials also tend to be healthier and better educated than typical patients. That may make the benefit look larger than it would be in everyday care. And participants always knew whether they were exercising.
Exercise as Part of Cancer Care
Current guidelines from the American Society of Clinical Oncology strongly recommend exercise to ease fatigue and loss of physical function. They stop short of calling it a way to control cancer. The American College of Sports Medicine and the Global Cancer Update Program's expert panel have called the evidence on survival "limited-suggestive."
"On the strength of this evidence, clinicians can reasonably recommend structured exercise as part of oncological care, while recognizing that important questions remain and that ongoing trials will continue to refine its optimal application," the authors wrote.
For patients undergoing cancer treatment or in recovery, tracking daily activity can help improve communication with the medical team. The Xiaoshu Health App can sync with Apple Health to track relevant metrics, helping you record exercise and body changes.