Fertility and pregnancy * Babies and children * Women's health

Breastfeeding reduces the risk of breast cancer

breastfeeding can reduce breast cancer risk in some women Risk lowered in women with a family history of the disease

Women with a family history of breast cancer are nearly 60% less likely to develop the disease if they breastfeed their babies, according to new research.

"This is good news for women with a family history of breast cancer," says Dr. Alison Stuebe, an assistant professor of obstetrics and gynaecology who led the study. "Our results suggest a woman can lower her risk of cancer simply by breastfeeding her children," Dr. Stuebe says.

In the study, scientists from the University of Carolina analysed data from more than 100,000 women from 14 different states in the USA.

Over 60,000 who became pregnant in 1997 were questioned in detail about breastfeeding and tracked until 2005 to find out how many developed breast cancer during that time.

The researchers found that women who had a mother or sister with breast cancer were 59% less likely to develop breast cancer if they had breastfed their children compared with women who had a family history of the disease who didn't breastfeed.

For women without a family history of breast cancer, breastfeeding had no detectable effect on breast cancer risk.

"This could be because there's something about genetically caused breast cancer that's affected by breastfeeding, or it could be because rates of breast cancer were so low in women without a family history that we couldn't see an association in this data set," said Dr. Steube.

Whether the woman had breastfed or not was more important than how long she had breastfed. When the scientists compared the risk of developing breast cancer in women who breastfed exclusively compared with those who supplemented their baby’s diet with other foods, they found there was no significant difference between the two groups.

For women with a family history, the reduction in risk with breastfeeding was similar to taking an anti-oestrogen drug such as Tamoxifen for five years. But unlike Tamoxifen, Dr. Stuebe says, "breastfeeding is good for mothers and for babies."

The scientists could not explain why breastfeeding reduces the risk of breast cancer. But they speculated that when women do not breastfeed, the inflammation and engorgement which happens shortly after birth causes changes in breast tissue that may increase a women's breast cancer risk. Breastfeeding may help prevent this inflammation.

In the UK, recent figures from the UK Infant Feeding Survey showed that 78% of women in England breastfed their babies at birth. This figure dropped to 50% by week 6 and 26% by six months. Current UK guidelines recommend all babies to be exclusively breastfed for six months (26 weeks).

More information

For more information about the benefits of breastfeeding: Breastfeeding information from the NHS

This article was published on Tue 11 August 2009

Image © Dmitrieva Daria - Fotolia.com

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