Researchers from the Fred Hutchinson Cancer Research Center in Seattle have good news for women suffering from migraines. These women appear to have a 30 percent lower risk of developing breast cancer, they say. Their study was published in the November issue of Cancer Epidemiology, Biomarkers & Prevention.

For the study, Dr. Christopher I. Li from the Fred Hutchinson Cancer Research Center and colleagues analyzed information on 3,412 postmenopausal women of whom 1,938 had been diagnosed with breast cancer and 1,474 had no history of the disease. The researchers followed the incidence of migraines in both groups and 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.”

How is that possible? Dr. Li says the biological mechanism behind the association is not fully known, but it likely has to do with fluctuations in the levels of circulating hormones.

“Migraines seem to have a hormonal component in that they occur more frequently in women than in men, and some of their known triggers are associated with hormones,” he says.

For example, women who take oral contraceptives for three weeks and then stop for a week to trigger menstruation tend to suffer more migraines during their hormone-free week. Women with higher levels of estrogen hormone are less likely to experience migraines, the researchers noted. The same hormone is known to stimulate the growth of hormonally sensitive breast cancer.

There could be also another explanation for the association between breast cancer and migraines, Dr. Li said. Women experiencing migraines may be more frequent users of nonsteroidal anti-inflammatory drugs (aspitin and ibuprofen). Previous studies showed that NSAIDs use prevents against breast cancer. However, that does not mean that women should start therapy with NSAIDs, Dr. Li cautioned. More study is needed before prescribing regular use of NSAIDs in order to keep breast cancer away, he added.

But the link between estrogen levels, migraines and breast cancer is highly negated by some researchers. Dr. Ellen Drexler, associated director of the Division of Neurology at Maimonides Medical Center in Brooklyn, N.Y., says it’s not clear that lower incidence of breast cancer in women with migraines proves that the reason is lower estrogen levels. It could be a number of factors raising a woman chance of having migraines such as medication use, smoking and alcohol use. Therefore, more study needs to be done before concluding that migraines might lower risk of breast cancer,Dr. Drexler adds.

Some other experts consider the findings as flawed. Migraine expert Dr. Stephen Silberstein, director of the Jefferson Headache Center at Thomas Jefferson University Hospital in Philadelphia believes the study does not prove anything. “It's not that I don't believe the results, it's that the results are not believable,” he said.