Breastfeeding for Two or More Years Halves Risk.(of developing breast cancer)

2001 FEB 15 - (NewsRx.com) -- Breastfeeding for two or more years reduces a woman's risk of developing breast cancer by 50%, according to a study conducted by a Yale University researcher among women in China.

The researcher, Tongzhang Zheng, Yale School of Medicine, said he conducted the study in China because, unlike Western nations, long-term breastfeeding is part of the Chinese culture. "In Chinese society, it is socially acceptable to breastfeed for along time," said Zheng. "And it is considered good for the child."

His research, published in the American Journal of Epidemiology, followed three studies conducted in the early 1980s in Shanghai, Beijing, and Tianjin, China. The earlier studies found a more than 50% reduction in breast cancer among women who reported a lifetime breastfeeding of more than 109 months compared to women who never breast-fed.

A limitation of that first study was that it only reported lifetime duration of lactation and breast cancer risk for all women. Recent studies from Western populations suggest that the effect of breastfeeding may be limited to pre-menopausal women and may be affected by other factors such as the number of children breast-fed and the age at first breastfeeding.

In 1997-1999, Zheng's group conducted a study in four large hospitals and several smaller hospitals in the Shandong Province of China to investigate the relationship between lactation and breast cancer risk.

This study, unlike the earlier research, included detailed information on menstrual and reproductive factors, number of children breast-fed, mean duration for each child breast-fed, lifetime duration of breastfeeding, and age at first breastfeeding. A total of 404 female breast cancer cases were identified from the ...