Cancer
Little Evidence That Having Been Breast-Fed Affects Cancer Development
By Journal of the National Cancer Institute
Oct 5, 2005, 04:17

A new study has found little or no evidence that being breast-fed as an infant is associated with cancer risk as an adult.

Exposures to environmental factors in infancy may influence cancer risk later in life. For example, breast feeding is associated with height and insulin-like growth factor 1 (IGF-1) levels in later childhood, and height and IGF-1 levels have been associated with the risk of some adult cancers. However, studies that relate having been breast-fed with later risks of cancer have been inconclusive.

To determine the associations between breast-feeding during infancy and adult cancer incidence and mortality, Richard M. Martin, B.M., Ph.D., of the University of Bristol in England, and colleagues analyzed 65 years of follow-up data from the Boyd Orr cohort--a group of nearly 5,000 subjects from Britain who were surveyed originally in 1937 to 1939 at ages 0 to 19--and also conducted a meta-analysis of this data and other published studies.

Neither analysis showed an association between having been breast-fed and incidence of either all cancers or of cancer at specific sites, including breast cancer. The meta-analysis did show a reduced risk of premenopausal breast cancer in breast-fed women, but the authors caution that the observed reduction could have arisen by bias or chance.

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