(McClatchy-Tribune Information Services) -- Nursing their infants appears to protect women with a family history of breast cancer from developing the disease, according to a report in the Archives of Internal Medicine.

Researchers used data from 60,075 women who participated in the Nurses' Health Study between 1997 and 2005 and who had given birth. They diagnosed 608 cases of pre-menopausal breast cancer in women with an average age just over 46.

What they found was that women with a close relative who had had breast cancer had a lower chance of getting the disease if they had breastfed their children.

The study also found that women who used medication to suppress breast milk production also had a lower risk of breast cancer than those who did not use the medication or who did not breastfeed.

"Future studies of interactions among breastfeeding history, family history and genotypes associated with breast cancer risk will be needed to confirm these associations and explore underlying mechanisms," the researchers wrote.

They found the reduced risk of breast cancer compared with high-risk women who were on hormones such as tomoxifen.

"Moreover, breastfeeding is associated with multiple other health benefits for both mother and child," they wrote. "These data suggest that women with a family history of breast cancer should be strongly encouraged to breastfeed."

Breast cancer is the most common cancer among women in the world, according to the article. Those at higher risk include those with a family history of breast cancer, those who begin menstruation at an early age and those who did not bear children or did so at a late age.

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