Breastfeeding Reduces Breast Cancer Risk

Scientists have long known that breastfeeding reduces a woman’s breast cancer risk. October is National Breast Cancer Awareness Month here in the United States. As part of a series of cancer-related posts, let’s revisit this incidental yet significant advantage of breastfeeding.

The results from the 2002 study are astonishing. For each year that a woman breastfeeds her children, there is a 4.3 percent decrease in her risk of breast cancer compared to women who never breastfeed. If women in developed countries like the United States increased the number of children they bear and increased the duration of breastfeeding to two years for each child (like mothers in developing countries in Asia and Africa), the breast cancer risk would be cut in half. While it’s unlikely that women in developed countries are going to significantly increase their child-bearing and extended breastfeeding, every little bit counts.

“The study concluded that if women had an average of two and one-half children and breastfed each child an extra six months, 5% of breast cancers would be prevented each year. If they breastfed their child for an additional 12 months, 11% of breast cancers would be prevented each year.”

Researchers have yet to determine exactly how breastfeeding reduces a woman’s breast cancer risk. Theories include: (1) physical changes in the milk-producing glands, (2) reduced levels of estrogen in the breast, and most likely (3) reduction in the number of times a woman ovulates during her lifetime. 

As if the reduction in breast cancer risk weren’t enough, extended breastfeeding also reduces the risks of ovarian cancer and osteoporosis.