Study: Women Who Breastfeed Less Likely To Have Breast Cancer Return
OAKLAND, Calif. (CBS Sacramento) -- Women who breastfeed their children and later develop breast cancer are less likely to have the cancer come back or die from it than women who do not breastfeed, new research suggests.
"We found in this study of over 1,600 women with breast cancer that those who previously breast-fed had a 30 percent overall decreased risk of their breast cancer recurring," said study leader Marilyn Kwan, a research scientist at the Kaiser Permanente division of research in Oakland, Calif., as reported by CBS News. "We also found those who previously breast-fed had a 28 percent reduced risk of dying from their breast cancer."
Researchers also noted that previous studies show that breastfeeding may prevent the risk of developing breast cancer to begin with. Kwan says women who breastfeed reduce their risk by about 5 percent to 10 percent. And although other factors are taken into consideration, researchers say this is one of the first studies to examine the role of breastfeeding and breast cancer outcomes.
"Overall, our study confirms that breastfeeding is not only good for the baby, but has potential health benefits for the mom," Kwan told CBS News.
The effect of lowering the chance of cancer's return or death from breast cancer is strongest among the most commonly diagnosed breast cancers. This study reinforces the notion that women who breastfeed get less aggressive breast cancer, while also examining new details on tumor types.
The study included two different groups of women. The women in the groups were diagnosed from 1997 to 2000 or from 2006 to 2013. The team of researchers found an association between breastfeeding and favorable outcomes for those diagnosed with breast cancer. The link was strongest with the most common subtypes of breast cancers known as luminal A sub-types. The research did not prove cause-and-effect and also did not find a strong link for other sub-types of breast cancer.
The overall reduced risk of breast cancer recurring among those who breast-fed was 30 percent. The link was strongest for those who breast-fed for six months or longer. Breastfeeding has proven to protect infants from diseases and other infections while decreasing the risk of breast and ovarian cancers for mothers.
Kwan and her team say that breast-feeding could be protective because it reduces the number of menstrual cycles in a woman's lifetime. Decreased menstrual cycles could lower the accumulated exposure to hormones that help certain cancers grow. Kwan also explained that breastfeeding helps build maturation of the ductal cells, possibly making them more resistant to cancer.
The study was published online April 28 in the Journal of the National Cancer Institute.
