Exercise Shown to Reduce Tumor Growth in Mice, Offers Hope for Humans

Research from Yale School of Medicine indicates that exercise can significantly slow tumor growth in mice by altering the body’s metabolism. This metabolic shift allows muscle cells to absorb glucose more effectively than cancer cells, potentially offering insights into how similar processes may affect humans.

In a study led by Rachel Perry, researchers injected breast cancer cells into 18 mice. Among these, 12 were placed on a diet designed to induce obesity, a condition known to worsen cancer progression. Half of the mice had unrestricted access to an exercise wheel, while the others did not exercise. After four weeks, tumors in the exercising obese mice were found to be 60 percent smaller than those in their sedentary counterparts. Remarkably, these tumors were also slightly smaller than those in sedentary mice on a normal diet.

The study highlights that even a 30-minute session of exercise can increase the uptake of oxygen and glucose in muscle tissues while decreasing glucose absorption in tumors. “This work reveals that aerobic fitness fundamentally reshapes metabolic competition between muscle and tumors,” said Perry. The voluntary nature of the exercise, which did not require the mice to undergo rigorous training, emphasizes the potential applicability of these findings to humans.

To understand the underlying mechanisms, the researchers analyzed gene activity and discovered changes in 417 genes associated with metabolic pathways. Specifically, they noted a down-regulation of the mTOR protein in cancer cells, which is pivotal for cell growth and may limit tumor expansion. Given these findings, Perry anticipates that similar metabolic responses could occur in humans, including those without obesity.

This research aligns with previous observations in humans, where similar alterations in gene activity have been documented during exercise in cancer patients. According to Rob Newton, a researcher at Edith Cowan University in Perth, Australia, these findings suggest that exercise creates a more cancer-suppressive environment. “We need a clinical trial in people, but I really can’t see any reason why you wouldn’t have a similar effect in humans,” he remarked.

Perry further elaborated on the interconnectedness of metabolism, the microbiome, and the immune system. She posited that metabolic changes could serve as a crucial link between exercise and its impact on tumor growth. “It’s possible that metabolic alterations could be the missing link between exercise, the microbiome, and the immune system,” Perry stated.

The implications of this research extend beyond the metabolic benefits of exercise. Newton indicated that low muscle mass is a significant risk factor for cancer mortality. He suggested that if muscle tissue preferentially absorbs glucose, individuals with greater muscle mass who engage in regular exercise may experience enhanced protective effects against cancer.

Newton advocates for a paradigm shift in how exercise is perceived within cancer treatment. “People should consider exercise as a cancer medicine to be used alongside other treatments rather than just a lifestyle choice,” he emphasized. This perspective encourages a targeted approach to combatting cancer, focusing on enhancing cardiorespiratory fitness while addressing low muscle mass through resistance training.

As research continues, the growing body of evidence underscores the importance of exercise in cancer prevention and management, highlighting the need for further clinical trials to explore these promising findings in human populations.