The Science Behind Exercise and Cancer Recurrence

At the Center for Integrative Oncology and Survivorship (CIOS), we have emphasized for cancer survivors the benefits of exercise and a healthy diet in lowering the risk of the cancer coming back. Observational studies indicate that exercise does indeed lower the risk of the cancer coming back. Recently, an article in Cell Metabolism described research in mice that explains how exercise can inhibit cancer. This blog will describe the research and what it means for cancer survivors.

Investigators in Denmark, led by Dr. Pernille Hojman at Copenhagen University Hospital, raised two groups of laboratory mice. One group of mice lived in cages with activity wheels that allowed them to exercise as much as they liked. The other group of mice lived in cages without activity wheels such that their exercise was limited to merely walking around in their cage. The scientists then caused cancers to grow in the mice by injecting chemicals and cancer cells. After allowing six weeks for the cancers to grow, the mice were carefully examined to determine how much the cancer grew in each group of mice. In five different experiments, the exercising mice had fewer cancers and smaller cancers than the non-exercising mice. It was clear that something was going on in the exercising mice that inhibited the growth of cancer cells.

The investigators went on to study why the cancers grew more slowly in the exercising mice. They were able to show that the advantage of the exercising mice was an increased number of immune cells in the blood, called natural killer T cells, compared to the non-exercising mice. Furthermore, they determined that the exercising mice had increased levels of two substances in the blood: epinephrine (adrenaline) and Interleukin 6 (Il-6). They put it together that the exercise increased the levels of adrenaline and Il-6 in the blood of the exercising mice led to an increase in the immune cells that gave the exercising mice the better ability to limit the growth of cancer cells.

This research has a number of applications. First, it may lead to the development of drugs and therapies that stimulate the immune system to control cancer. Second, it can motivate us to keep up our own exercise routine. This morning, when I dragged myself out of bed to exercise, I did not have to ask, “Why am I doing this?” I knew why. It was to raise the adrenaline and Il-6 levels in my blood to stimulate my immune system to grow more natural killer T cells. I hope that this encourages you, too, as you work toward your moderate exercise at 30 minutes per day and 150 minutes per week.

The Center for Integrative Oncology and Survivorship exists to help cancer survivors enjoy the benefits of exercise. To learn more or to make an appointment for integrative oncology consultation, call (864) 455-1346 or find us on the web at

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