To Fight Cancer, Try Adding Exercise

Cancer remains one of the leading causes of death worldwide, yet recent studies suggest there may be a simple tool to help lower risk and improve outcomes: physical activity.

In a recent study in Proceedings of the National Academy of Sciences, Rachel Perry, PhD, associate professor of medicine (endocrinology and metabolism) and of cellular and molecular physiology at Yale School of Medicine (YSM), demonstrated that voluntary wheel running among mice slowed tumor growth. The research team found that working muscles outcompete tumors for glucose, depriving the tumor of the fuel they need to grow. The study’s findings suggest that exercise can play a part in the prevention and treatment of cancer.

“By exercising, individuals may be able to boost the body's defenses against cancer, perhaps improving immune function and surveillance,” Perry says. “Exercise may also create a greater window in which chemotherapy, radiation therapy, or immunotherapy can work.”

Research has shown that exercise helps the body reverse insulin resistance, which is a metabolic condition that can cause a range of metabolic and cardiovascular issues. In individuals with insulin resistance, insulin’s signal does not properly trigger the muscle’s glucose transport system. This is largely because ectopic fat, or fat buildup in muscle or liver cells, interferes with the normal signaling pathway.

“Our hypothesis is that insulin resistance is driving many obesity-related cancers,” says Gerald I. Shulman, MD, PhD, George R. Cowgill Professor of Medicine (endocrinology) and professor of cellular and molecular physiology at YSM.

“Exercise activates an important enzyme, called AMPK, which acts as a cellular fuel gauge and promotes glucose uptake into muscle cells, even when insulin signaling is impaired,” Shulman adds. “In this way, exercise can reverse ectopic lipid-induced insulin resistance in skeletal muscle.”

“The overarching conclusion from the literature showing the benefits of exercise in fighting cancer is remarkably consistent,” says Melinda Irwin, PhD, MPH, Susan Dwight Bliss Professor of Epidemiology (chronic diseases) at Yale School of Public Health and deputy director of Yale Cancer Center.

Metabolic and inflammatory biomarkers likely mediate the effect of exercise on cancer risk and prognosis, research shows. Irwin’s study of exercise and diet-induced weight loss in women with breast cancer found significant reductions in C-reactive protein (a protein associated with inflammation in the body), insulin and leptin levels.

“Across cancer types and across the lifespan, any increase in physical activity is better than none,” Irwin says. “It is never too late to begin exercising, as individuals who become active later in life or after diagnosis still experience meaningful benefits.”

Perry and Irwin both recommend walking regularly, minimizing prolonged sitting, and maintaining muscle strength with simple, home-based exercises.

While healthy lifestyle choices can lower risk, they cannot guarantee that a person will not develop cancer. “Exercise is not a panacea. It can put a monkey wrench in cancer progression, but it will never treat cancer as a monotherapy,” says Perry. “Even so, it still has beneficial effects all over the body.”

Endocrinology and Metabolism, one of 10 sections in the Yale Department of Internal Medicine, improves the health of individuals with endocrine and metabolic diseases by advancing scientific knowledge, applying new information to patient care, and training the next generation of physicians and scientists to become leaders in the field. To learn more, visit Endocrinology and Metabolism.