July 9 (HealthDay News) -- For women who suffer from migraines, here's a bit of good news: New research shows that your risk of breast cancer may be reduced by as much as 26 percent.

And, no matter what a woman's age or what migraine triggers a woman might be avoiding, the risk of breast cancer is still reduced, according to the study, which appears in the July issue of Cancer Epidemiology, Biomarkers & Prevention.

"In this study, we evaluated the relationship between migraine and breast cancer risk and found that women who have migraine have a 26 percent lower risk of breast cancer than women without a history of migraine," said study author Dr. Christopher Li, an associate member of the epidemiology program at the Fred Hutchinson Cancer Research Center, in Seattle.

Li said the researchers don't know exactly why women who get migraines appear to have a reduced breast cancer risk, but they suspect that hormones, particularly estrogen, are a likely explanation.

"It's pretty clear that migraine, like breast cancer, is a hormonally related disease. Many triggers for migraine are also things that reduce estrogen levels," he said. It's well-known that many breast cancers are fueled by estrogen.

Li and his colleagues first reported the possible connection between migraine and breast cancer risk last fall in a study of postmenopausal women. That study found a reduction in the risk of breast cancer of about 33 percent among women with migraine.

The current study included data from 4,568 women with breast cancer and 4,678 women without breast cancer. The age of the women ranged from 34 to 64, which was significantly younger than the group included in the last study.

The researchers found that women who had a history of migraine had a 26 percent reduced risk of developing breast cancer. This reduced risk didn't change even when the researchers factored in menopausal status, age at migraine diagnosis, use of prescription medication and headache trigger avoidance (which includes avoiding alcohol, hormone use or smoking).

"This research suggests that women with migraine may have a lower risk of breast cancer," said Li, who added that women with migraines should "still have the same breast cancer screenings and follow-up."

Dr. Michael Kraut, director of oncology at Providence Hospital in Southfield, Mich., agreed that women with migraine still need to be vigilant about assessing their breast cancer risk. "The reduction in breast cancer risk in this study was about one-quarter, but it doesn't eliminate the risk, so women still need to be on the lookout."

Kraut said the link between migraines and breast cancer risk is likely a hormonal one. "The theory they propose here is that women who have migraines may have drops in estrogen levels that trigger migraines. And women who have sustained, increased levels of estrogen have a higher risk of breast cancer. This looks like one more piece of evidence that prolonged high levels of estrogen are dangerous," he said.

SOURCES: Christopher Li, M.D., Ph.D., associate member, epidemiology program, Fred Hutchinson Cancer Research Center, Seattle; Michael Kraut, M.D., director, oncology, Providence Hospital, Southfield, Mich.; July 2009 Cancer Epidemiology, Biomarkers & Prevention