Breast-Feeding May Decrease Risk of Breast Cancer

Posted to findingDulcinea by Shannon Firth

Seattle’s Fred Hutchinson Cancer Research Center has found that breast-feeding for at least six months decreases the risk of contracting luminal cancer, and a type of cancer known as triple negative cancer, which is common among African Americans and Hispanics, especially in younger women. While the link between breast-feeding and reduced breast cancer risk isn’t new, the specific discovery of its effects on triple negative cancer is.

Triple negative cancer, a particularly aggressive form, was given its name because it is unaffected by the regulatory protein HER2, along with the hormones estrogen and progestin. Breast cancer researcher Dr. Funmi Olopade explained the significance of triple negative cancer, saying, “We don’t know the risk factors, we don’t know how to screen for it, and we don’t know how best to treat it.” This cancer type comprises about 15 to 30 percent of all breast cancers.

Amanda Phipps and her colleagues studied over 2,500 women, aged 55 to 79, roughly half of whom had cancer and half who didn’t. Researchers took the women’s reproductive histories, including their breastfeeding habits, start of menopause and age at which their menstrual cycle began.

Phipps proposed two theories: one explanation for the reduced risk is that a woman who is breast-feeding has stopped menstruating and her “hormones aren’t cycling”; a second possibility is that the cell structures in a woman’s breast change in such a way that they might be less capable of forming cancerous cells.

Phipps and her colleagues also showed that the late onset of menopause and the use of hormone treatment increase the chances of contracting luminal cancer.

Last year, The Washington Post expressed the concern of many researchers troubled by the question: “Why are black women, who are less likely to get the disease than white women, more likely to get it when they are young—and much more likely to die from it?” The finding that black women are more likely to get the most aggressive type of breast cancer, triple threat cancer, only partially answered their question. Now scientists are hoping to find out whether the causes are genetic or environmental.

Recent studies showed that 70 percent of cancer in black women in Nigeria and Senegal is triple threat cancer, which suggests a genetic basis. Yet Robert Millikan of the University of North Carolina, points out that black women are less likely than white women to breast-feed, implying that environmental factors are also involved.

Otis W. Brawley, an Emory oncologist, sees the discussion as moot: “Even if we find a great new treatment for triple-negative breast cancer tomorrow, I already have the data to show that a large proportion of black women aren’t going to get it.”