Breastfeeding Reduces Breast Cancer Risk in High-risk Women

Posted on August 12th, 2009 by

Among women with a first-degree family history of breast cancer, breastfeeding cut the risk of premenopausal breast cancer by more than half. These results were published in the Archives of Internal Medicine.

Each year in the United States, close to 200,000 women are diagnosed with breast cancer. Although some risk factors for breast cancer are things that a woman cannot change (such as her age or family history of breast cancer), others may be modifiable. By identifying modifiable risk factors, researchers hope to increase options for cancer prevention.

Some studies have suggested that breastfeeding reduces the risk of breast cancer, but results have not been entirely consistent.

To further evaluate the relationship between breastfeeding and risk of breast cancer, researchers evaluated information from more than 60,000 parous women (women who had given birth) in the Nurses’ Health Study II. The analysis focused on premenopausal breast cancer.

  • Compared with women who had never breastfed, women who had breastfed were 25% less likely to develop premenopausal breast cancer. Duration of breastfeeding did not appear to influence cancer risk.
  • The relationship between breastfeeding and breast cancer risk varied by whether or not a woman had a family history of breast cancer. Among women with a first-degree family history of breast cancer (breast cancer in a parent, sibling, or child), breastfeeding cut the risk of breast cancer by more than half. In contrast, among women without a family history of breast cancer, breastfeeding did not appear to influence the risk of breast cancer.

These results suggest that breastfeeding may reduce the risk of premenopausal breast cancer in women with a family history of breast cancer.

Reference: Stuebe AM, Willett WC, Xue F, Michels KB. Lactation and Incidence of premenopausal breast cancer: A longitudinal study. Archives of Internal Medicine. 2009;169:1364-1371.

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