Migraines can be a real headache, but women who suffer from them have at least one thing in their favor: They appear to have a lower risk of breast cancer.

A large, multicenter study recently showed that women reporting a history of migraines were 26 percent less likely to develop breast cancer than women who lived migraine-free.

Leslie Bernstein is a key researcher in the Women’s Contraceptive and Reproductive Experiences Study. (Photo by Walter Urie)

Both migraines and breast cancer risk are linked to levels of female hormones, explained Leslie Bernstein, Ph.D., professor and director of the Division of Cancer Etiology and dean for faculty development at City of Hope. Bernstein is a co-author of the paper, which appeared in the July 1 issue of Cancer Epidemiology, Biomarkers & Prevention.

“Higher levels of circulating estrogen in the body over a lifetime are associated with higher breast cancer risk,” Bernstein said. “Plunging levels of estrogen in the body appear to spur the onset of migraines. We might speculate that that the lower levels of estrogen that provoke migraines may result in lower risk for breast cancer, although we need to conduct more research to understand the biology behind the relationship between the two conditions.”

Researchers leading the Women’s Contraceptive and Reproductive Experiences Study enrolled nearly 4,600 women age 35 to 64 who developed breast cancer in the mid-to-late 1990s. The women lived in Atlanta, Detroit, Los Angeles, Seattle and Philadelphia. For comparison, researchers matched them to nearly 4,700 other similar women who had not had breast cancer.

Age and menopausal status can affect women’s risk for migraines, Bernstein said, but several other potential breast cancer risk factors also trigger them. These factors include smoking, drinking alcohol and using hormone therapy. Scientists thought migraine sufferers might have a lower breast cancer risk because they avoided these triggers, but study results showed that was not the case.

They also suspected that lower breast cancer risk among migraine sufferers might be due to their use of nonsteroidal anti-inflammatory drugs, or NSAIDs, such as ibuprofen. Research has shown that NSAIDs can lower breast cancer risk. “Although frequent NSAID use might lower risk somewhat, it’s unlikely to entirely explain the entire risk reduction we saw among these women,” Bernstein said.

Researchers hope to further study the role of hormones and NSAIDs and other medications in breast cancer risk.

Christopher I. Li, M.D., Ph.D., M.P.H., of the Fred Hutchinson Cancer Research Center, was the paper’s lead author. Other institutions in the study include the Keck School of Medicine of the University of Southern California, the Centers for Disease Control and Prevention (CDC), the University of Pennsylvania, the Karmanos Cancer Institute at Wayne State University, Baystate Medical Center in Massachusetts, and the National Institute of Child Health and Human Development (NICHD).

The NICHD, CDC and National Cancer Institute supported the study.