There are many studies demonstrating the link between decreased physical activity and cancer (1,7-9). Sedentary jobs are associated with a 60% increased risk of colon cancer (9,10). Men who exercise 1 to 2 hours a day have a 50% decrease in colon cancer. The Harvard University study of 48,000 professional men controlled for dietary factors including fiber intake and found that physical activity alone lowers risk of colon cancer (10). Similar studies have demonstrated that a sedentary lifestyle is associated with increased risk of breast and uterine cancer for women and prostate cancer for men (9,11).
The American College of Sports Medicine, ACS, and the American Heart Association recommend at least 30 minutes of brisk physical activity-above usual physical activity-on five or more days per week to reduce the risk of various types of cancers (1,12). Increasing to 45 to 60 minutes of exercise further reduces the risk of colon and breast cancers. Activity recommendations extend to children and adolescents. There is an increasing trend of overweight and obesity in young people, thereby increasing their lifetime risk of cancer. To counter this trend, the ACS recommends at least 60 minutes of moderate-to-vigorous physical activity at least 5 days of the week (11). Previously sedentary men older than 40 years or women older than 50 years or people with cardiovascular risk need to consult with a physician before starting a new exercise program. The same is true for sedentary people with chronic medical conditions.
Dietary changes are important for prevention because of the link between overweight and obesity and cancer (7,8,11). Increased calorie intake and weight gain are associated with increased circulating insulin and hormone levels. Hormones are associated with the regulation of growth and replication of different cell types; excessive levels may lead to increased growth of abnormal cells. Eating five servings of fruits and vegetables each day is important. Besides increasing dietary fiber, fresh fruits and vegetables contain cancer-fighting antioxidants, vitamins, and minerals. Properly prepared fruits and vegetables are usually lower in calories than processed foods, helping to control weight. Eating more whole-grain foods and less processed and red meats helps to reduce risk of colon cancer (9,11).
Another simple measure to prevent cancer is the use of proper sun protection. More than one million squamous and basal cell skin cancers can be prevented every year with the use of sunscreen and by limiting sun exposure. Simple vaccinations for HPV and HBV vaccines can prevent cancer. Proper treatment of H. pylori and HIV infections can prevent other cancers.
Screening also is important in both cancer prevention and early treatment. Cancer-related costs of indirect morbidity (time lost for illness) and direct mortality demonstrate the need for early diagnosis and effective treatment. Currently, more than 17% of Americans younger than 65 years do not have any health insurance, and many more lack adequate coverage. Of Americans older than 65 years, 25% have Medicare insurance only (1). Although there are screening tools for many types of cancer, the lack of adequate health care coverage prevents many from being screened. Another obstacle is the lack of education about the need for screening.
The U.S. Centers for Disease Control and Prevention (CDC) provides funding for screening programs and community education to increase awareness of cancer prevention and facilitate early treatment (Table 3) (5,8). The National Breast and Cervical Cancer Early Detection Program provides 6.5 million screening and diagnostic breast examinations for low-income women every year. It pays for breast examination, mammogram, and Papanicolaou screening with participating providers. Screen for Life: National Colorectal Cancer Action Campaign promotes screening for colorectal cancer in low-income individuals older than 50 years. The program is only available to people in a few states but is evaluating barriers to proper screening nationwide. The CDC has a lung cancer initiative to prevent and control tobacco use, especially in young people. Because there is no screening test for lung cancer, it is very important to prevent starting and promote smoking cessation. The Division of Nutrition and Physical Activity has a national campaign-Promote a Healthy Diet: 5 a Day-to reduce risk of cancer by encouraging people to eat five or more fruits or vegetables a day. Other CDC funding includes programs for prostate (Prostate Cancer Screening: A Decision Guide) and skin (Guidelines for School Programs to Prevent Skin Cancer) cancers.
In summary, more than one third of all cancers can be prevented. Increased physical activity can prevent many forms of cancer. Tobacco avoidance, cessation of smoking, weight loss, and other lifestyle modifications can further reduce cancer risk. Appropriate screening can diagnose some common forms of cancer early, facilitating cancer treatment and extending productive life.
1. American Cancer Society. Cancer Facts and Figures-2006
. Atlanta: American Cancer Society, 2006.
6. Grulich, A.E., M.T. van Leeuwen, M.O. Falster, et al. Incidence of cancers in people with HIV/AIDS compared with immunosuppressed transplant recipients: a meta-analysis. The Lancet
10. Neiman, D.C. The Exercise-Health Connection
. 1st ed. Champaign: Human Kinetics, 1997.
© 2008 American College of Sports Medicine
12. Haskell, W.L., I.M. Lee, R.R. Pate, et al. Physical activity and public health: updated recommendation for adults from the American College of Sports Medicine and the American Heart Association. Circulation