Exercise May Boost the Immune System and Improve Cancer Vaccine Effectiveness

Center for Cancer Research

A great deal of epidemiological evidence shows that regular physical activity lowers the risk of developing certain types of cancer, especially cancers of the colon and breast. Scientists have proposed that exercise may protect against cancer by boosting the body’s immunity, in particular the immune system’s ability to detect cancerous cells and prevent tumor formation. But the immune system is complex; the effects of exercise on this intricate system are not well understood.

John W. Greiner, Ph.D., a staff scientist at NCI’s Center for Cancer Research (CCR), is studying this question in collaboration with Connie J. Rogers, Ph.D., M.P.H., an assistant professor at Penn State University. “There’s been this knowledge that regular, moderate exercise can enhance the ‘innate’ immune response, the part of the immune system that immediately reacts to infection,” explained Dr. Greiner. “But we looked at whether voluntary exercise can influence the ‘adaptive’ arm of the immune system” which recognizes and remembers infectious agents such as viruses, enabling the body to quickly eliminate disease-causing organisms when infections recur. This “memory” aspect of the immune system is also responsible for the body’s response to vaccines.

Dr. Greiner’s research group within CCR’s Laboratory of Tumor Immunology and Biology is developing vaccines against prostate and colon cancer. They are interested in ways to increase the effectiveness of anticancer vaccines, and Dr. Rogers was interested in the role voluntary exercise plays in cancer risk.

The researchers did a study* of young, healthy mice that had a propensity for exercising on running wheels. These mice served as an animal model for the effects of moderate, voluntary exercise in humans. Half of the mice in the study had access to running wheels, while the other half did not. After eight weeks, all of the mice were vaccinated with a vaccine that was known to trigger a strong response by the immune system. Dr. Greiner and his colleagues then examined multiple aspects of the immune response in the mice to see if they could build on the response to the vaccine with voluntary exercise.

They found that “in those mice that were running for eight weeks, you get a higher immune response to the vaccine,” said Dr. Greiner. The most important finding, he added, “is that we were increasing the immune cells that have memory.”

If a similar immune response to exercise occurs in humans, “there are two ways that this could impact prevention of cancer,” Dr. Greiner explained. “The first is that just by exercising, you could boost your immune system without a vaccine. The second is that if you have a cancer vaccine, you might be able to increase the effectiveness of that vaccine through exercise,” he added.

To investigate these possibilities, Dr. Greiner and Dr. Rogers are collaborating on follow-up studies in both mice and humans. In a strain of mice that is prone to tumors, they are examining whether voluntary exercise can increase the effectiveness of a cancer vaccine that Dr. Greiner’s group has developed. He is also establishing collaboration with colleagues in NCI’s Cancer Prevention Branch, who are studying whether a 10,000-step daily exercise regimen can help prevent cancer recurrence in women who have had surgery for breast cancer. In an effort to translate his findings to humans, he hopes to ask some women in the study to provide blood and tissue samples that he can analyze to see if the women’s immune response has been heightened due to the exercise.