Breast-feeding protection extends to hereditary cancer

Journal of the National Cancer Institute 2004; 96: 1094-98

Examining whether the protection against overall breast cancer afforded by breast-feeding also applies to the hereditary forms, BRCA1 and BRCA2.

Breast-feeding may lower the risk of breast cancer among women carrying the BRCA1 tumor suppressor mutation, research suggests.

While several studies indicate that breast-feeding lowers the odds of breast cancer, overall, the impact on hereditary breast cancer is not known, note H. Jernstom (Lund University Hospital, Sweden) and colleagues.

To address this issue, they conducted a case-control study of 3959 women with BRCA1 or BRCA2 mutations, including 1927 with invasive breast cancer while the remainder had no such disease. All the participants were surveyed about their pregnancy and breast-feeding histories.

Among women with BRCA1 mutations, the risk of developing breast cancer fell by an odds ratio of 0.98 for each month of breast-feeding reported. Moreover, those who breast-fed for 1 year or longer were significantly less likely to develop the disease than those who had never breast-fed, with an odds ratio of 0.55. No such association was noted, however, among women with BRCA2 mutations.

Although the sample of women with BRCA2 mutations was too small to preclude a modest association with breast-feeding, the authors nevertheless speculate: "The difference between women with BRCA1 and BRCA2 mutations may reflect underlying differences in the pathogenesis of cancers associated with the two genes."

Posted: 27 July 2004