(photo credit: Courtesy)
Breastfeeding one's baby can reduce by up to 59 percent the risk of breast cancer in women who have a family history of the disease, including those who have inherited the BRCA1 or BRCA2 mutation that is more commonly found in Jewish women in Israel and abroad, according to research published Monday in the prestigious Archives of Internal Medicine.
The major study - by obstetrics and gynecology Prof. Alison Stuebe and colleagues of the University of North Carolina at Chapel Hill School of Medicine - can provide relief to women in such a situation who have reduced their risk of the cancer only by undergoing frequent examinations by their doctors or undergoing prophylactic surgery to remove their breasts.
It follows numerous studies that show breastfeeding reduces the risk of breast cancer among women in general. But having a family history of breast cancer, especially being the carrier of a BRCA mutation, can raise the lifetime risk beyond that of other women by as much as 80 percent.
Among women with a mother or sister with breast cancer, the researchers found that those who had breastfed were less than half as likely to develop premenopausal breast cancer as those who had not breastfed.
For women with a family history, the reduction in risk with breastfeeding was similar to taking an anti-estrogen drug such as Tamoxifen for five years. But unlike Tamoxifen, Stuebe says, "Breastfeeding is good for mothers and for babies."
Stuebe and colleagues reviewed data from the Nurses' Health Study II, a long-term study of more than 100,000 women from 14 US states. Stuebe's study followed more than 60,000 women who reported at least one pregnancy in 1997, when breastfeeding was assessed in detail, and followed them through 2005 to determine how many developed invasive breast cancer.
How long a woman breastfed seemed to be less important than whether or not she had breastfed, Stuebe says. The reduction in risk was similar whether women breastfed for a lifetime total of three months or for more than three years. Also, there was no significant difference in risk for women who breastfed exclusively versus those who breastfed while supplementing with other foods.
"At last - a positive study that is a continuation of the research of many years" that shows that breastfeeding is beneficial to mothers without a family history, commented Wendy Blumfield of the Israel Childbirth Education Center.
"One of the theories is that menstruation usually resumes later after delivery when a woman is lactating and that the resulting fewer menstrual cycles in itself reduces the hormonal upheaval that can contribute to the risk of breast, ovarian and uterine cancers. The theory mentioned in this study, that women who do not breastfeed have a greater tendency to infections and breast inflammation in the days and weeks following birth is also plausible.
"When one reflects that lactation is the natural conclusion to the hormonal changes of pregnancy and birth, it is logical that this would contribute to the future health of the mother."
Blumfield added one word of caution.
"Inflammatory breast disease in premenopausal women is easily masked if a woman is still or has recently stopped breastfeeding. In my work I have unfortunately heard of women who have presented symptoms to their doctors, only to be brushed off with an explanation that they are caused by engorgement or other breastfeeding changes that in themselves are quite benign. So without unduly scaring women who are worried about unusual changes in the breasts that do not resolve themselves within a few days, I would urge them to get a thorough check at a breast clinic or with a qualified breast specialist."
Commenting on the new research, the Israel Cancer Association said it endorses the recommendation of breastfeeding not only for babies' health but also to help protect the mothers against breast cancer.
The ICA noted that the increasingly lower age at the onset of menstruation among girls in Western countries - due to improper diet and inadequate exercise - raises the risk of eventual breast cancer, and that when girls reach adulthood and give birth, they should nurse their babies if possible to cut their risk.