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Obesity and Breast Cancer

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Li Liu, MD
Last Modified: November 1, 2001

I learned from your site and others that there are many risk factors for breast cancer. My question is whether larger waist size is a risk factor for breast cancer.  
Thanks!

Li Liu, MD, OncoLink editorial assistant, responds:

Dear D:  
Thank you for your interest and question.

Obesity (large waist size) has a complex relation to risk of developing breast cancer. Higher body mass index (weight (kg)/height (m2)) is associated with a lower risk of breast cancer before menopause and with an increased risk of cancer after menopause, particularly among women who do not use postmenopausal hormones (JAMA 1997 Nov 5; 278(17): 1407-11). The question of whether body fat distribution contributes further to the risk of breast cancer is of considerable debate. In some studies, central obesity measured by either waist circumference or waist: hip circumference ratio has been associated with increased risk of breast cancer among postmenopausal women, whereas the association has been weak or equivocal among premenopausal women (Breast Cancer Res Treat 1995 May; 34(2): 129-37; Int J Cancer 1992 Apr 22;51(1):14-9). But in another study, no significant association was observed (Br J Cancer 1994 Feb; 69(2): 352-7). In a recent study from Harvard School of Public Health, a total of 47,382 US registered nurses were followed for 8 years for identification of incident cases of breast cancer (Am J Epidemiol 1999 Dec 15; 150(12): 1316-24). Waist circumference was identified as a risk factor for breast cancer, particularly in postmenopausal women who have never taken hormone replacement therapy.

More research is needed to better understand the impact and association of obesity on breast cancer risk. But, it is important to know that obesity is clearly related to heart disease, hypertension, and diabetes risks. The American Cancer Society recommends maintaining a healthy weight and limiting your intake of high-fat foods, particularly those from animal sources.