Lifestyle vs. Breast Cancer Risk

Lifestyle vs. Breast Cancer Risk

By: Allison D. Salibian, B.S., CPT

July 8, 2014

No one can accurately predict an individual’s risk for breast cancer, but there have been recent studies which have helped illuminate ways to protect against it.  Each year, researchers for the American Cancer Society and the Women’s Health Initiative, among other groups, learn more about how a woman's lifestyle and health habits -- how much she weighs, the amount she exercises, what she eats -- can affect her risk of developing breast cancer.

Most Americans are overweight.  Approximately 2/3 of the U.S. population has a BMI above 25 (1).  Unfortunately, this fact goes hand-in-hand with the current breast cancer statistics: about 1 in 8 U.S. women (just over 12%) will develop invasive breast cancer over the course of her lifetime (1).  At what point does being overweight start to increase a woman's risk for breast cancer?  A recent American Cancer Society Study found that women who gained 21-30 pounds since age 18 were 40% more likely to develop breast cancer than women who had not gained more than 5 pounds, and women who gained 70 pounds doubled their risk (2).  Further, excess weight greatly increases the risk for metastatic tumors, which are more difficult to treat than tumors that have not spread. Women who gained more than 60 pounds since age 18 were 3 times more likely to have metastatic breast cancer than women who gained less than 20 pounds as an adult (3).

Most Americans do not exercise enough.  The U.S. Department of Health and Human Services (HHS) defines a minimum standard of exercise for adults as 150 minutes of moderate exercise or 75 minutes of vigorous intensity (4).  These guidelines are echoed by the American Heart Association, the American Cancer Society, and the American Medical Association, to name a few.  Activities considered moderate are those that make you breathe as hard as you would during a brisk walk. This includes things like walking, biking, and even housework and gardening. Vigorous activities generally engage large muscle groups and cause a noticeable increase in heart rate, breathing depth and frequency, and sweating. 

Physical activity affects breast cancer in 2 distinct ways: directly, by influencing circulating hormones, and indirectly, by helping to control a person’s fat content.  The more fat in a woman’s body, the more stored estrogen.  The more estrogen, the more potential stimulation of cell overgrowth and breast cancer.  Additionally, the ratio of “good” estrogens to “bad” estrogens (those which can damage DNA and increase breast cancer risk) can be improved by roughly 25% with appropriate exercise (5).  The Women’s Health Initiative found that women who followed the exercise guidelines set forth by the HHS had 18% less risk of breast cancer than women who were considered “inactive” (6).

Most Americans do not eat right.  Harvard researchers recently found that women who had the highest carotenoid levels in their blood had a 19% lower risk of breast cancer than those with the lowest levels (7).  Carotenoids are found in vegetables such as leafy greens, carrots and red peppers.  Women who consumed more carotenoids had an even lower risk of developing estrogen-receptor-negative breast cancer, which is often more aggressive.  Other nutrients, such as lycopene (the chemical that gives tomatoes their red color) have been suggested to protect against breast cancer.  Further, regular consumption of more than one alcoholic drink per day is associated with an increased risk of breast cancer, according to the American Cancer Society’s latest research, particularly in women who do not consume enough of the vitamin folate.  Therefore, for women who do drink, reducing alcohol may be an important way to reduce breast cancer risk.  The American Cancer Society recommends that all women, but especially those who drink regularly, eat five or more servings of fruits and vegetables a day, with emphasis on leafy greens and folate-rich vegetables, carotenoid-containing fruits and vegetables and other cruciferous veggies.

References:

1.       American Cancer Society, Infographics, 2013:1

2.       Breastcancer.org/symptoms/understand_bc/statistics

3.       American Cancer Society, Cancer.org, Lifestyle v. Cancer, 2013

4.       U.S. Department of Health and Human Services, Health.gov, 2008 PAG Handout

5.       Cancer Epidemiology, Biomarkers and Prevention, 2013

6.       Stopping Breast Cancer, Prevention, October 2013

7.       Elaissen, et al., Circulating Carotenoids and Risk of Breast Cancer: Pooled Analysis of Eight Prospective Studies, JNCI J Natl Cancer Inst (2012). First published online: December 6, 2012