Women who have a family history of breast cancer could reduce their risk of developing early onset of the disease by 59 percent if they breast-feed their babies, scientists at UNC-Chapel Hill and other centers reported Monday.
The current research offers the strongest evidence yet that breast-feeding is a powerful cancer-prevention tool among high-risk women, specifically younger women who have not gone through menopause.
The benefit, which is more effective than taking a preventive regimen of the anti-cancer drug tamoxifen, appears to occur even when women breast-feed for a short period.
"The bottom line is this is really good news for women with a history of breast cancer," said Dr. Alison Stuebe, lead author of the study and an assistant professor of obstetrics and gynecology in the Division of Maternal Fetal Medicine at UNC-Chapel Hill.
The study, which focused on the cancer risk for women prior to menopause, was published Monday in the Archives of Internal Medicine.
Breast-feeding advocates hailed the results as clear evidence that women should try to nourish their babies naturally. In North Carolina, about 76 percent of women initiate breast-feeding, but only 51 percent continue to eight weeks, according to the N.C. State Center for Health Statistics.
"I think this is huge," said Mary Overfield, a lactation consultant at WakeMed and an advocate with the N.C. Breastfeeding Coalition. "I have several friends who are breast cancer survivors, and you better believe they'd have done anything they could to cut their risk."
She said efforts to encourage women to try breast-feeding often focus on benefits to the baby, including fewer weight problems, allergies and ear infections.
Mothers also reap health advantages, notably a reduced risk of type 2 diabetes. Some studies had noted the lower risk of developing breast cancer, while other studies found no association.
Anything to cut risk
Catherine Kurmay, a mother of four in Apex, said she had banked on the earlier studies when she chose to breast-feed her first child seven years ago.
"It was the No. 1 reason," she said, noting that her aunt, grandmother and great-grandmother had breast cancer. "I wanted to cut my risk in any form or fashion."
Enlisting more than 60,000 participants from a massive study of nurses, the breast cancer arm of the study was specifically designed to explore links between breast-feeding and breast cancer.
Researchers surveyed participants about childbirth and breast-feeding, as well as cancer occurrences, at regular intervals between 1997 and 2005.
Among women whose mothers, grandmothers or sisters had breast cancer, those who breast-fed their babies had a 59 percent reduction in incidences of premenopausal breast cancer compared with women who bottle fed.
The findings provided other surprises.
Women who did not have a family history of cancer saw no statistically significant protective effect of breast-feeding.
Also, among the high-risk participants who did breast-feed, it didn't matter how long they kept it up or whether they supplemented breast milk with formula.
And high-risk women who did not breast-feed and took drugs that were once widely used to inhibit milk production after their babies were born also saw decreased incidences of cancer.
Stuebe said the results, which warrant more study, suggest there may be a correlation between breast engorgement after giving birth and cancer later in life.
"This is a huge, huge exclamation point to the understanding of the health benefits of breast-feeding," said Dr. Miriam Labbok, director of the Carolina Breastfeeding Institute in UNC-CH's Gillings School of Global Public Health. "It can save lives, and it can save health-care costs."
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