Among the many other wonderful benefits associated with breastfeeding, studies have associated breastfeeding with lower rates of breast cancer for both the mother and for the baby being breastfed. Below, I explore the available research to understand the connection between breastfeeding and lower breast cancer rates.

According to breastfeeding expert Jack Newman, M.D., the benefit to mothers was not revealed in some early studies which combined results from women who had breastfed for only a few days with those who breastfed for much longer durations.

According to a study in the peer-reviewed journal, Cancer, in October 2008, "Women who breastfed for [greater than or equal to] 6 months had reduced risks of both luminal (OR of 0.8; 95% CI, 0.6-1.0) and triple-negative disease (OR of 0.5; 95% CI, 0.3-0.9) compared with parous women who had never breastfed." Jack Newman, M.D. states in his excellent resource "The Ultimate Breastfeeding Book of Answers (2006) that "the greater the total number of months of breastfeeding, the lower the risk of developing breast cancer." (p.12)

I personally attended a lecture in 2004 given by a representative of the American Cancer Society that also referenced this phenomenon. According to our speaker, the reducing total number of menstrual cycles over a lifetime, through later menarche, earlier menopause, number of months pregnant and number of months breastfeeding all reduced the likelihood of reproductive cancers by reducing lifetime hormonal exposure.

On the website of the American Institute for Cancer Prevention (AICP), in their "Recommendations for Center Prevention" they recommend exclusive breastfeeding for 6 months, stating "Breastfeeding lowers the levels of some cancer-related hormones in the mother¡¯s body, reducing the risk of breast cancer. At the end of breastfeeding, the body gets rid of any cells in the breast that may have DNA damage. This reduces the risk of breast cancer developing in the future."

The AICP also addresses the increased risk of cancer seem among formula-fed babies, stating that "Research shows that babies who are breastfed are less likely to consume too many calories and too much protein than babies who are fed infant formula. This means that they are less likely to become overweight or obese as they grow up." Elsewhere on that page they mention that overweight adults have a higher cancer risk.

Jack Newman references a study (in the book mentioned above - page 9) that formula fed infants showed a shocking 33.3% increase in breast cancer rates compared to women breastfed as infants! One wonders if more women were presented with this data would choose to make extended breastfeeding an essential priority, and if health insurance companies aware of these statistics would realize the wisdom of funding breastfeeding support for newborns and new mothers as opposed to cancer treatment later in life.

I have two friends who have lost mothers early in life due to breast cancer who were especially concerned with breastfeeding their babies due to concerns about their family history. While I knew this has basis, I was shocked to see how significant a factor it could be, both for themselves, as well as their daughters. With some history of breast cancer in my family as well, of which I only became recently aware, I am glad to have 5+ years of breastfeeding between my two daughters.

As my readers know, I've been a breastfeeding advocate for quite some time, and have known vaguely about the connection between breastfeeding and breast cancer. But having now researched the specifics, this may be even the most medically compelling reason I have seen to avoid formula and to promote exclusive breastfeeding for at least 6 months. Please help to spread the word on the effects of formula feeding vs. breastfeeding on breast cancer rates ¨C you could save a life!