Can you run away from cancer? It sounds like a silly question, but new research suggests that regular, vigorous exercise helps protect people from cancer. In addition, metastatic spread is far less common among people who exercise hard, whether they run, swim, dance or bike.
How Does Vigorous Exercise Affect Cancer?
Scientists have long acknowledged that regular exercise helps prevent cancer. They have not known exactly why, however. Past studies have confirmed that exercised lowers the risk of both prostate and breast cancer, for example.
Prostate Cancer Is Less Deadly Among Exercisers:
In a study of nearly 200 men who underwent prostate biopsies, those who walked at least three hours or more each week were less likely to be diagnosed with prostate cancer (Journal of Urology, Nov. 2009). Even the veterans diagnosed with a tumor were less likely to have high grade disease if they got regular vigorous exercise. At that time, the investigators speculated that exercise may lower testosterone levels, which could act like fertilizer for abnormal prostate cells.
That same year, a study of male health professionals provided a similar message. Vigorous exercise may be the most effective way men with prostate cancer can prolong their lives. Investigators at the Harvard School of Public Health analyzed data from more than 2,500 men who were diagnosed with prostate cancer (Journal of Clinical Oncology, Feb. 20, 2011). Those who were most physically active significantly reduced their chance of dying during the study. Despite these promising findings, however, the investigators could not explain the mechanism.
Active Women Have a Lower Risk of Breast Cancer:
Middle-aged women might be less likely than men to engage in vigorous exercise. However, research on more than 3,000 women on Long Island demonstrated that exercisers are less likely to develop breast cancer after menopause (Cancer, online June 25, 2012). Regular exercise, between 10 and 19 hours a week, during childbearing years reduced the risk of postmenopausal breast cancer by one third. But even women who didn’t start exercising until menopause lowered their risk of breast cancer compared to their sedentary peers.
Recreational Activity and the Risk of Cancer:
A big meta-analysis looked at data from 12 different studies enrolling a total of 1.44 million adults (JAMA Internal Medicine, June 1, 2016). Some people reported high levels of physical activity during their leisure time. They were significantly less likely to have cancer than those who did very little vigorous activity. This association held for most types of cancer. Once again, however, the investigators were unable to explain exactly how exercise protects people.
Could Vigorous Exercise Alter Metabolism?
Recently, scientists have begun to consider the role of metabolism in the spread of cancer. Might vigorous exercise be reducing insulin resistance, which is a risk factor for certain cancers? A study of more than 90,000 Chinese adults that lasted 13 years found the highest risk for colorectal cancer among people with insulin resistance (BMC Cancer, Sep. 22, 2022).
Another recent study suggests that this link could be crucial. Among several types of data, the researchers collected 20 years of information on 2,734 people (Cancer Research, Nov. 15, 2022). Once they noted that physical activity reduced the chance of metastatic tumors by 72 percent, the scientists turned to mice for a closer look. Just as with humans, mice who ran a lot were much less likely to develop metastatic cancers.
To learn why, the investigators analyzed the organs to compare those of active mice to those of sedentary animals. High-intensity aerobic activity increased the number of glucose receptors in the tissues. Regular vigorous exercise helps convert organs into efficient utilizers of glucose, similar to muscle tissue. According to the scientists, these metabolic changes reprogram the tissue if the physical activity is maintained. In the discussion. they posit a “metabolic shield” against metastasis due to tissue competing more successfully for energy.
They conclude:
“Exercise protects against cancer progression and metastasis by inducing a high nutrient demand in internal organs, indicating that reducing nutrient availability to tumor cells represents a potential strategy to prevent metastasis.”
We can’t think of many more compelling reasons to put on your dancing shoes, or your running shoes, and get moving!
