Breastfeeding Can Help Prevent Cancer

While reports most often emphasize the positive benefits of breastfeeding for the infant, recent studies reveal important benefits for the nursing mother as well. Women who breastfeed have increased protection against breast cancer in addition to cervical, ovarian and endometrial cancers.

A 2002 study published in the British medical journal The Lancet collaboratively analyzed individual data from 47 studies in 30 countries, including 50,302 women with breast cancer and 96,973 without the disease. The study found that a woman’s risk for breast cancer decreased by 4.3 percent for every 12 months she breastfed during her lifetime. The risk also decreased 7 percent for every child born.

According to the data, breast cancer in some African and Asian countries is relatively uncommon compared to occurences in the United States and many countries in Europe. The difference is that women in less developed countries have many more children and breastfeed much longer than their counterparts in developed countries.

“The dramatic changes that have occurred in childbearing over the past 50 to 75 years really can explain a fairly large amount of breast cancer incidence in developed countries,” says Eugenia Calle, director of analytic epidemiology for the American Cancer Society.

The study did not explore the reasons why breastfeeding appears to decrease the risk of breast cancer, but researchers speculate that it could be because breastfeeding lowers a woman’s exposure to estrogen. Another theory is that fat-soluble pollutants and carcinogens are not stored as long in lactating breasts than in non-lactating breasts.  Whatever the cause, the take-home message of this study is a clear indication that breastfeeding is one way to reduce the risk of breast cancer.

A significant body of evidence also suggests that breastfeeding can reduce the risk of cervical, ovarian and endometrial cancer. A 2002 study published in the American Journal of Epidemiology analyzed 12 case-controlled studies and showed that women who breastfed an infant had a 20 percent lower risk of developing ovarian cancer. A 1986 study in the New England Journal of Medicine found that lactation reduces estrogen, decreases stimulation of the uterine lining and appears to offer protection from endometrial cancer. In 1989, a study reported in the Medical Journal of Australia found that breastfeeding protected against uterine cancer as well.

Although much of this evidence comes from epidemiologic studies rather than long-term controlled trials, various considerations support the conclusion that breastfeeding has a protective effect against cancer.  The observed connections are strong, evidenced in multiple studies, biologically sensible and not explained away by differences in other risk factors.

While the American Academy of Pediatrics recommends breastfeeding for at least 12 months, the World Health Organization, which helped to fund the study on breast cancer reported in The Lancet, suggests women continue “to breastfeed up to two years or longer.”

Views about breastfeeding in this country have been changing over the last decade. Today, nearly 69 percent of women breastfeed right after giving birth. However, this number drops sharply to about 29 percent after six months. Knowing the tremendous health benefits to the baby as well as the nursing mother, it is in our best interests as a community to support women and ensure mother and child are encouraged, validated and made to feel comfortable with extended nursing.

-----------------------
Dawn Parker-Waites is a freelance writer and mother of a teenage daughter and a toddler son who were each breastfed for eighteen months.