A large study found that breastfeeding one baby -- even for as little as 3 months -- reduced the risk of breast cancer before menopause by 59% in women with higher-than-average risk compared to high-risk women who never breastfed.
Women in the study were considered high-risk if they had at least one first-degree relative (a mother or a sister) diagnosed with breast cancer.
Other research has shown clearly that women who have given birth to one or more babies have a lower risk of breast cancer than women who have never been pregnant. Other studies also have shown that breast cancer risk is lower among women who have breastfed one or more babies, but this link between breastfeeding and lower risk hasn't been found consistently in all studies.
In this study, the link between breastfeeding and lower pre-menopausal breast cancer risk was found only in women who were considered to have a higher-than-average risk. Breastfeeding didn't seem to lower pre-menopausal breast cancer risk in women who didn't have a first-degree relative diagnosed with breast cancer. The researchers aren't sure why this is.
Some premenopausal women with higher-than-average breast cancer risk can lower their risk by taking tamoxifen, usually for 5 years. Tamoxifen is a hormonal therapy medicine and works by blocking the effects of estrogen on breast cancer cells. This study found that breastfeeding -- even for a short period of time -- lowered pre-menopausal breast cancer risk about as much as taking tamoxifen for 5 years. Still, the researchers said that pre-menopausal women at high risk should talk to their doctors about the benefits of BOTH breastfeeding and tamoxifen. Breastfeeding may lower pre-menopausal breast cancer risk even more in high-risk women who choose to take tamoxifen.
Choosing to breastfeed is a personal decision. For some women, it may be more practical to bottlefeed. Still, breastfeeding for even a short time offers important health benefits to both mother and baby. For women with a family history of breast cancer, one of these benefits may be lower breast cancer risk.
If you have a family history of breast cancer and have higher-than-average risk, the information in the Lower Your Risk section can help you better understand risk and the choices you can make to keep your risk as low as it can be.