Endometrial cancer, otherwise known as uterine cancer, is the fourth most common cancer in women in high-income countries, including the United States, Canada, and Australia. There’s no shortage of things you shouldn’t do if you want to avoid cancer, such as using tobacco or drinking alcohol. As some research points out, another thing women can do to lower their risk of endometrial cancer is to breastfeed their babies.
The World Health Organization (WHO) recommends that women exclusively breastfeed for the first 6 months of their child’s life and then continue to do so after introducing solid food to their baby. The United Nations also notes how ‘breastfeeding is directly linked to reducing the death toll of children under five,’ encouraging women around the world to breastfeed.
Susan Jordan of the QIMR Berghofer Medical Research Institute in Brisbane, Australia, told Reuters:
“Cancer of the uterus is becoming more common and we need to try to prevent it. The more women know about the things they can do to reduce their risks of future cancer diagnosis, the better.” 
Jordan and her colleagues teamed up to investigate possible correlations between breastfeeding and endometrial cancer. They analyzed data from 17 studies participating in the Epidemiology of Endometrial Cancer Consortium. Ten of the studies were from the U.S., and the others were from Canada, Europe, China, and Australia. Data were available from over 26,000 mothers, including 9,000 with endometrial cancer. The team searched for whether the women breastfed and, if so, for how long. 
The researchers found that breastfeeding for any period of time lowered the risk of endometrial cancer and that mothers who breastfed for the recommended six months decreased their risk even further. Breastfeeding beyond nine months appeared to offer no additional benefit. However, women who breastfed their children for any length of time lowered their risk of endometrial cancer by 11% compared to those who had children but didn’t nurse them at all.
“Although this piece of evidence by itself may not convince women to breast-feed, it contributes to the overall picture of health gains that can come from breast-feeding.” 
“Breast-feeding has consistently been found to be associated with reduced risk of breast cancer. This provides evidence of another long-term health benefit for women who breast-feed for more than six months.” 
The protective effects of breastfeeding remained, even after the researchers accounted for age, race, education, oral contraceptive use, menopausal status, years since last pregnancy, and body mass index.
In women born after 1950, breastfeeding reduced the risk of endometrial cancer by 28%, but the risk reduction was negligible among women born before then, possibly reflecting differences in breastfeeding practices. For example, in the U.S. in the 1950s and 1960s, breastfeeding rates were considerably lower than in recent decades. 
The study does not prove cause and effect, the researchers wrote. But it would make sense that breastfeeding would lower the risk of endometrial cancer, as this type of the disease is fueled by estrogen. Breastfeeding suppresses the hormone.
“The message is not only relevant for women making decisions about breast-feeding but also for society to understand the benefits so we can support women to breast-feed for reasonably long periods of time.
However, it’s not always possible for women to breast-feed, so it should also be noted that just because a woman chooses not to or can’t breast-feed, it doesn’t mean she’ll go on to develop cancer.” 
Jordan and her colleagues have also teamed up with international collaborators to study the effects of breastfeeding on ovarian cancer risk. In addition, the scientists are investigating other factors that may influence endometrial cancer risks, including specific medications. 
Breastfeeding has also been linked to numerous other health benefits, including prevention of heart disease.
 Reuters/Fox News