Breast-feeding Cuts Risk of Premenopausal Breast Cancer by Half in High-Risk Women
A study published yesterday (Aug 10, 2009) in The Archives of Internal Medicine concluded that breast-feeding is inversely associated with the incidence of breast cancer among high-risk women, i.e., among women who have a family history of breast cancer.
Results of this study are noteworthy for several reasons. This was a prospective cohort study with a large sample size. In this study, researchers followed 60,075 women for more than nine years. These women were participants in the cohort of the Nurses’ Health Study II from 1997 to 2005. Due to the fact that data from large, prospective cohort studies had thus far been lacking to study the relationship between lactation and incidence of premenopausal breast cancer; this study adds significantly to our body of knowledge on this subject.
Researchers in this study found that breast-feeding did not affect premenopausal breast cancer risk for women who didn’t have breast cancer in their family. However, for women with at least one close relative with breast cancer — a sister, mother, or daughter – breast-feeding cut the risk of premenopausal cancer by 59 percent compared to those who didn’t breast-feed. The main results of the study suggest that:
1) Nursing can cut the risk of breast cancer in more than half for high-risk women, and
2) The effect of breast-feeding may be the equivalent of taking the drug Tamoxifen for 5 years in those who are at high-risk for breast cancer.
Given that at present, the only conventional options for pro-actively preventing breast cancer for women who are at high risk are Tamoxifen use or Prophylactic Mastectomy – the results of this study represent good news.
My comments: This study supports previous observational data on the inverse association between lactation and premenopausal breast cancer; its results are thus confirmatory in nature. Still, it is important to bear in mind that it is generally not feasible, or even possible, for any one study to rule out all confounding variables that contribute to either the genesis or the prevention of disease. For example: Nutritional status, body weight, and lifestyle factors are relevant variables in either the genesis or the prevention of breast and other cancers. It is difficult to know to what extent these other factors may also have played a role in the lower rates of cancer among the high-risk, breast-feeding women.
The bottom-line: Based on the evidence thus far, breast-feeding is highly advisable, especially for women who have a family history of breast cancer. In light of the larger body of research, close attention to maintaining body weight at a normal level, as well as achieving an optimal nutritional status is equally advisable.
Resources:
Lactation and Incidence of Premenopausal Breast Cancer
