The relationship between exercise and cancer

Exercise benefits the body in myriad ways. Studies have shown that routine exercise can help people effectively maintain healthy weights, sleep better at night and have more energy throughout the day. But exercise also may play a role in preventing one of the world’s most deadly diseases.

The World Health Organization notes that cancer is annually responsible for about one in six deaths across the globe, making it the second leading cause of death in the world. Many of those deaths can be prevented by employing some simple yet effective strategies, such as avoiding tobacco products and applying sunscreen before going out in the sun. And while researchers aren’t exactly sure why, the National Cancer Institute notes that substantial evidence suggests high levels of physical activity are linked to lower risks of several cancers.

The relationship between exercise and cancer risk is complicated. The NCI notes that nearly all of the evidence that links physical activity to cancer risk comes from observational studies. In such studies, individuals report on their physical activity and are then followed for years to see if and when they are diagnosed with cancer. While such studies are no doubt valuable, they cannot definitively establish that physical inactivity causes cancer or that physical activity prevents cancer. All they can do is establish a link between physical activity and lower cancer risk.

As mysterious as the relationship between exercise and cancer can seem, researchers can theorize about the connection between the two. For example, the Dana-Farber Cancer Institute notes that scientists have recently begun probing the connections between exercise, the immune system and cancer risk. Such research is rooted in the notion that exercise can reduce inflammation, an acute or chronic response by the immune system that can contribute to cancer risk.

The NCI also notes that the many biological effects of exercise on the body might shed light on the potential link between routine physical activity and a lower cancer risk. For example, the NCI says exercise lowers levels of certain hormones, such as insulin and estrogen, that have been linked to cancer development and progression. Exercise also has been linked to improved immune system function, and a stronger immune system is more capable of fighting various conditions and diseases, including cancer.

The relationship between routine exercise and cancer remains a mystery in many ways. But the potential for exercise to lower cancer risk is yet another reason for people of all ages to embrace physically active lifestyles.