One in four women complains of regular migraines. But this annoying episode may have a good part: as a research published in the November issue of the journal Cancer Epidemiology, Biomarkers and Prevention shows, regular migraines indicate a lower risk of developing breast cancer.

According to the study, women with a history of migraines were 30 percent less likely to suffer from breast cancer, compared to women who did not have a history of such headaches.

The 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.

The biological mechanism behind this phenomenon is not fully known, Dr. Christopher I. Li from the Fred Hutchinson Cancer Research Center, lead author of the study said. “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 explained.

The main factor that may be taken into consideration when discussing the association between migraines and a lower risk of breast cancer are the hormonal fluctuations, which are known to stimulate the growth of hormonally sensitive breast cancer. Estrogen-receptor (ER)-positive breast cancer accounts for the majority of breast cancers diagnosed each year. About 75% of breast cancers are estrogen-receptor positive.

Women with higher levels of estrogen hormone are less likely to experience migraines, the researchers noted. As an example, pregnancy, a high estrogen state, is associated with a significant decrease of migraines. In late pregnancy, when estrogen levels are high, 80% of women with a history of severe headache do not have such episodes.

Another possible explanation for this association may be medication, such as nonsteroidal anti-inflammatory drugs (aspirin and ibuprofen) which have been shown to reduce breast cancer risk.