September 14, 2009

Breastfeeding is great for babies and moms, offering the best nutrition along with bonding opportunities. Now, studies show that breastfeeding cuts the risk of breast cancer as well.

How? Breastfeeding appears to lower the levels of cancer-related hormones. At the end of lactation, the mother’s body also gets rid of many breast cells, including some that may have DNA damage, thereby reducing her risk of developing cancer later.

Since the early 1990s, Robert Millikan, PhD, DVM, Barbara Sorenson Hulka Distinguished Professor of epidemiology in the UNC Gillings School of Global Public Health, and other researchers have studied the inverse relationship between breastfeeding and breast cancer.

A 1999 study by Millikan and then UNC graduate student Helena Furberg, published in the International Journal of Epidemiology, found that breastfeeding may reduce cancer risk by up to 30 percent (20 percent in women aged 20-49; 30 percent in women aged 50-74) and was protective regardless of the number of children breastfed or maternal age during lactation. (Furberg is now research assistant professor of genetics in the UNC School of Medicine.)

A landmark expert report, “Food, Nutrition, Physical Activity and the Prevention of Cancer: a Global Perspective,” published in January 2008 by the American Institute for Cancer Research (AICR) and the World Cancer Research Fund (WCRF UK), confirms this view (www.dietand The report reviewed 100 studies and found “satisfactory evidence” (requiring the most convincing data) that breastfeeding reduces breast cancer risk. A separate analysis of 47 published studies reported a decrease in risk of 4.3 percent for every year of breastfeeding.

Millikan and colleagues Drs. Charles Perou and Lisa Carey at the UNC Lineberger Comprehensive Cancer Center recently extended Millikan’s earlier work to show that breastfeeding is protective for one of the most aggressive types of breast cancer, termed basal-like. This form is difficult to treat and is more common in younger African- American women than other groups.

Miriam Labbok, MD, professor of the practice of public health and director of the Carolina Global Breastfeeding Institute (in public health’s Department of Maternal and Child Health) sees the research as a steppingstone to better education for women, especially black women.

Labbok says the School’s job is to ensure that “these messages are not only heard, but supported and practiced, so that all women someday will be truly enabled to make the best preventive health choices for themselves and their children.”

Current recommendations for breast feeding:
Breastfeed exclusively for six months; then supplement with other food (recommended by AICR and WCRF ).

Other ways to reduce cancer risk:

  • increase physical activity
  • improve eating habits
  • lower alcohol consumption
  • maintain a healthy weight

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— Linda Kastleman

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