Physical Activity and Cancer (Fact Sheet)
Regular physical activity aids in cancer prevention
• Physical activity is a critical component of energy balance, the term researchers use to describe how weight, diet, and physical activity influence health.
• There is strong evidence that physical activity is associated with reduced risk of cancers of the colon and breast.
• Several studies have also reported links between physical activity and reduced risk of endometrial (lining of the uterus), lung, and prostate cancers.
• Current National Cancer Institute-funded studies are exploring the role of physical activity in cancer survivorship and quality of life, cancer risk, and the needs of populations at increased risk.
What is physical activity?
Physical activity is any bodily movement produced by skeletal muscles; such movement results in an expenditure of energy. Physical activity is a critical component of energy balance, a term used to describe how weight, diet, and physical activity influence health, including cancer risk.
How is physical activity related to health?
Researchers have established that regular physical activity can improve health by:
- Helping to control weight.
- Maintaining healthy bones, muscles, and joints.
- Reducing the risk of developing high blood pressure and diabetes.
- Promoting psychological well-being.
- Reducing the risk of death from heart disease.
- Reducing the risk of premature death (1).
In addition to these health benefits, researchers are learning that physical activity can also affect the risk of cancer. There is convincing evidence that physical activity is associated with a reduced risk of cancers of the colon and breast. Several studies also have reported links between physical activity and a reduced risk of cancers of the prostate, lung, and lining of the uterus (endometrial cancer). Despite these health benefits, recent studies have shown that more than 50 percent of Americans do not engage in enough regular physical activity (2).
How much physical activity do adults need?
The Centers for Disease Control and Prevention (CDC) recommend that adults “engage in moderate-intensity physical activity for at least 30 minutes on five or more days of the week,” or “engage in vigorous-intensity physical activity for at least 20 minutes on three or more days of the week” (1). Examples of moderate-intensity and vigorous-intensity physical activities can be found on the CDC Physical Activity Web site at http://www.cdc.gov/nccdphp/dnpa/physical/pdf/PA_Intensity_table_2_1.pdf on the Internet.
What is the relationship between physical activity and colon cancer risk?
Colorectal cancer has been one of the most extensively studied cancers in relation to physical activity, with more than 50 studies examining this association. Many studies in the United States and around the world have consistently found that adults who increase their physical activity, either in intensity, duration, or frequency, can reduce their risk of developing colon cancer by 30 to 40 percent relative to those who are sedentary regardless of body mass index (BMI), with the greatest risk reduction seen among those who are most active (3–7). The magnitude of the protective effect appears greatest with high-intensity activity, although the optimal levels and duration of exercise are still difficult to determine due to differences between studies, making comparisons difficult. It is estimated that 30 to 60 minutes of moderate to vigorous physical activity per day is needed to protect against colon cancer (6, 7). It is not yet clear at this time whether physical activity has a protective effect for rectal cancer, adenomas, or polyp recurrence (3).
Physical activity most likely influences the development of colon cancer in multiple ways. Physical activity may protect against colon cancer and tumor development through its role in energy balance, hormone metabolism, insulin regulation, and by decreasing the time the colon is exposed to potential carcinogens. Physical activity has also been found to alter a number of inflammatory and immune factors, some of which may influence colon cancer risk.