Mothers who breastfeed have a lower risk of developing breast cancer. That is one of the findings of a report of the American Institute of Cancer Research (AICR), which was released to mark World Breastfeeding Week in early August.
The 2017 report, Diet, Nutrition, Physical Activity and Breast Cancer, is a joint effort of AICR and the World Cancer Research Fund (WCRF), and is the result of systematic literature review on breast cancer. An independent panel of world-renowned experts evaluates and interprets the evidence and makes conclusions about what increases and decreases cancer risk.
One area of study in the report is lactation. It identified and reviewed 18 studies on lactation, 13 of which focused on duration, showing a 2% decreased risk of breast cancer per five-month increase in breastfeeding. While the lower risk is modest, it is one additional reason to breastfeed for moms who are able, researchers say.
"It isn’t always possible for moms to breastfeed but for those who can, know that breastfeeding can offer cancer protection for both the mother and the child,” says AICR’s Director of Nutrition Programs Alice Bender, MS, RDN.
AICR recommends that new mothers breastfeed exclusively for up to six months and then add other liquids and foods. This advice is in line with recommendations of other health organizations, including the World Health Organization. Breastfeeding provides the nutrients babies need, helps protect them from infections and asthma, and boosts their immune system.
There are several possible reasons that breastfeeding may influence breast cancer risk, according to the report. Lactation may delay a new mother’s menstrual periods, reducing lifetime exposure to hormones such as estrogen, which is linked to breast cancer risk. Also, the shedding of breast tissue after lactation may help rid cells with potential DNA damage.
“With the many benefits of breastfeeding, it’s important that new moms get support to successfully breastfeed for longer than a few days or weeks,” Bender says. “I am a strong proponent that lactation, education and support should really be a normal part of pre- and postnatal care.”