ACSM'S Health & Fitness Journal:
Departments: You Asked For It: Question Authority
Nieman, David C. Dr.P.H., FACSM
David C. Nieman, Dr.P.H., FACSM, is professor and director of the Human Performance Laboratory, Appalachian State University in Boone, North Carolina. He is an active researcher and author of several textbooks on health and fitness. Email your questions to: firstname.lastname@example.org.
Q: SEVERAL OF MY FRIENDS DURING THE PAST FEW YEARS HAVE BEEN DIAGNOSED WITH BREAST CANCER. WHAT CAN I DO TO PREVENT THE ONSET OF BREAST CANCER?
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A: There is much you can do to lower your risk of breast cancer, and these strategies center around early detection and lifestyle changes including weight control and physical activity.
The American Cancer Society (ACS) recently reported that breast cancer death rates continue to fall by around 2% a year, as it has since 1990 (1). This impressive decrease is largely due to advances in early detection and treatment and because many women stopped taking hormone replacement therapy (HRT). The ACS report, titled "Breast Cancer Facts & Figures 2007-2008," also shows that approximately 2.4 million U.S. women have a history of breast cancer (1).
One worrisome trend according to the U.S. Centers for Disease Control and Prevention is that fewer women are getting regular mammograms, the best way of detecting early breast cancer when it is most treatable. In fact, 98% of women diagnosed with early breast cancer through mammograms are alive 5 years later, mainly because physicians have multiple successful strategies to treat breast cancer when caught early. Women should have annual mammograms starting at age 40 or even earlier if breast cancer runs in the family (1).
Despite the good news, more than 40,000 women will die of breast cancer this year, a rate superseded only by lung cancer. Of all cancer diagnoses, one in four in women is breast cancer. Early detection through mammograms is important, but prevention through lifestyle changes is another equally significant strategy. Steps you can take to prevent breast cancer include the following:
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▸ Control your weight. Weight gain during adulthood and obesity after menopause increase the risk of breast cancer (2,3). Do all you can to keep your food intake under control and maintain a healthy weight. In postmenopausal women, having more fat tissue increases estrogen levels and the likelihood of developing breast cancer (1). Women who gain 55 lbs or more after age 18 have approximately 1.5 times the risk of breast cancer compared with those who avoid weight gain (2). A large proportion (65%) of women in the United States are overweight or obese. Thus, the battle against breast cancer cannot be completely won until women avoid the typical weight gain that is common during adulthood.
▸ Keep alcohol intake moderate. Women who have two alcoholic drinks a day on a regular basis increase their risk of breast cancer by 21% (1). Most health agencies recommend that women have only one alcoholic drink a day. The most likely reason for the link between alcohol consumption and breast cancer is that alcohol increases estrogen levels.
▸ Be physically active. Women who exercise for 45 to 60 minutes on 5 days or more a week also can lower their breast cancer risk (1). And for postmenopausal women, any amount of regular exercise reduces the risk of breast cancer (4). Recent studies show that the protective effect of physical activity against breast cancer can be measured in African Americans, Asian Americans, and whites (5-7). About three in four studies support a 30% to 40% protective effect of physical activity against breast cancer, with the best results seen in lean and highly active women that have been consistently exercising all their lives. Exercise may reduce breast cancer risk through several mechanisms including improved energy balance and lowered estrogen levels.
▸ Limit HRT. The routine use of HRT by postmenopausal women to prevent osteoporosis and heart disease is no longer recommended. If you and your physician decide that HRT is needed to treat specific menopausal symptoms or health problems, use the lowest effective dose for as short a time as possible (1).
By the way, studies have not been able to support the wide variety of fanciful theories regarding the causes of breast cancer including underwire bras, certain types of antiperspirants, breast implants, a history of abortion (either spontaneous or induced), or environmental pollutants, such as organochlorine pesticides (1).
Interestingly enough, no strong link has been found between diet and breast cancer, including dietary factors such as fat intake, fruit and vegetable consumption, antioxidant vitamins, dairy consumption, intake of soy products and isoflavones, and green tea (8,9).
Women have a one in eight chance of developing breast cancer during their lifetimes (1). There is no guaranteed way to prevent breast cancer, which is why regular mammograms are so important. Nonetheless, your best overall preventive health strategy is to reduce known risk factors as much as possible by avoiding weight gain and obesity, engaging in regular physical activity, and minimizing alcohol intake. It is never too late to become lean and fit. One study showed that losing at least 22 lbs after menopause and maintaining this weight loss lowered breast cancer risk by 57% (2). Also consider with your physician the increased risk of breast cancer associated with HRT use when evaluating treatment options for menopausal symptoms.
1. American Cancer Society. Breast Cancer Facts & Figures 2007-2008
. Atlanta: American Cancer Society, Inc. 2007.
2. Eliassen, A.H., G.A. Colditz, G. Rosner, et al. Adult weight change and risk of postmenopausal breast cancer. The Journal of the American Medical Association
3. Feigelson, H.S., A.V. Patel, L.R. Teras, et al. Adult weight gain and histopathologic characteristics of breast cancer among postmenopausal women. Cancer
4. McTiernan, A., C. Kooperberg, E. White, et al. Women's Health Initiative Cohort Study. The Journal of the American Medical Association
5. Bernstein, L., A.V. Patel, G. Ursin, et al. Lifetime recreational exercise activity and breast cancer risk among black women and white women. Journal of the National Cancer Institute
6. Yang, D., L. Bernstein, and A.H. Wu. Physical activity and breast cancer risk among Asian-American women in Los Angeles: a case-control study. Cancer
7. Sprague, B.L., A. Trentham-Dietz, P.A. Newcomb, et al. Lifetime recreational and occupational physical activity and risk of in situ and invasive breast cancer. Cancer Epidemiology, Biomarkers & Prevention
8. Michels, K.B., A.P. Mohllajee, E. Roset-Bahmanyar, et al. Diet and breast cancer: a review of the prospective observational studies. Cancer
109(12) (Suppl.):2712-2749, 2007.
9. Linos, E., and W.C. Willett. Diet and breast cancer risk reduction. Journal of the National Comprehensive Cancer Network