Women are more likely than men to suffer from migraine headaches, and there may actually be a benefit to it: a reduced risk of breast cancer. A new study from the Fred Hutchinson Cancer Research Center in Seattle shows that women with a history of migraines were 25% less likely to develop breast cancer.

The research was led by Dr. Christopher I. Li, and the results back up an earlier study which was also conducted by Li and his team. The first study included 2,000 women, and showed a 33% lower breast cancer risk among women with migraines. Li's latest study included 9,000 women and showed a 26% lower risk.

In their report, the researchers noted that low estrogen levels appear to increase the severity and frequency of migraines in women. Increased levels of the hormone are known to increase the risk of breast cancer, so they conclude that it is "biologically plausible" that migraine sufferers would be less prone to developing breast cancer.

In the latest study, researchers compared 4,568 women with breast cancer (age 34 to 64) to 4,678 healthy controls. In this study they accounted for the effects of migraine triggers, such as smoking, alcohol or hormone use, which hadn't been done in their first study. They found a 26% lower risk of breast cancer in women with migraines, which did not change when they took into account migraine triggers or whether or not a woman was menopausal. The use of prescription drugs for migraines did not change the risk.

Li and his colleagues did say that migraine sufferers' greater use of non-steroidal anti-inflammatory drugs (NSAIDS), such as ibuprofen and naproxen, could explain some but not all of their lower risk. It should be noted that a recent analysis of several studies linked NSAID use to a 12% lower risk of breast cancer.

A report of the study appears in the July 2009 edition of Cancer Epidemiology, Biomarkers & Prevention.