"We found that, overall, women who had a history of migraines had a 30 percent lower risk of breast cancer compared to women who did not have a history of such headaches," said Dr. Christopher Li of the Fred Hutchinson Cancer Research Center in Seattle, whose findings appear in the journal Cancer Epidemiology, Biomarkers and Prevention.
The risk dropped for the most common types of breast cancers -- those driven by hormones, such as estrogen-receptor positive breast cancer, which is fueled by estrogen, and progesterone-receptor positive breast cancer, which is fueled by progesterone.
Hormones also play a role in migraines, which are often accompanied by nausea, vomiting and heightened sensitivity to light and sound. Women are two to three times more likely than men to get migraines.
Researchers suspect hormones are the key, but they also said it is not exactly clear why women with a history of migraines had a lower risk for breast cancer.
Researchers analyzed data from two studies of 3,412 post-menopausal women in the Seattle area, 1,938 of whom had been diagnosed with breast cancer and 1,474 of whom had no history of breast cancer. Women in the study provided information on their migraine history.
They found women who had reported a clinical diagnosis of migraine had a 30 percent reduced risk of developing hormonally sensitive breast cancers.
Breast cancer is the leading cause of cancer death among women worldwide, with an estimated 465,000 deaths annually, according to the American Cancer Society.
