Wednesday, July 15, 2009

Migraine Sufferers Appear to Have Reduced Risk of Breast Cancer

Almost everyone gets headaches at one time or another, but for millions of Americans who have migraines, they are more than just an occasional annoyance; they are often disruptive and debilitating. The pain is a severe throbbing on one or both sides of the head that can last for hours, or even days, and is often accompanied by nausea, dizziness, and sensitivity to light, sound or smells. But scientists say there is a bright spot for women who suffer these disabling headaches, and it’s not an aura.

A new study, led by Dr. Christopher I. Li of Fred Hutchinson Cancer Research Center in Seattle, comparing data on more than 9,000 women revealed that women with a history of migraines have a 26 percent reduced risk of breast cancer. This held true regardless of the woman’s menopausal status, age when she was first diagnosed with migraines, whether she used prescription medications for her headaches, or what triggers she might have been avoiding. These findings confirm a previous study reported last November, also by Li and his team, which found a 33 percent lower breast cancer risk among women with migraines. “This research suggests that women with migraine may have a lower risk of breast cancer,” said Li, adding that it could lead to a new way of understanding how breast cancer works. “If we can better understand what the biological mechanisms are, that could open new avenues for research into breast cancer prevention.”

While the researchers aren’t sure exactly why women who get migraines appear to have a reduced breast cancer risk, they suspect that hormones, estrogen in particular, are a likely explanation. “It’s pretty clear that migraine, like breast cancer, is a hormonally related disease,” Li said. “Many triggers for migraine are also things that reduce estrogen levels.” On the other hand, increased levels of estrogen are known to boost the risk for breast cancer, therefore it’s “biologically plausible” that migraine sufferers would be less prone to breast cancer.

The researchers say increased use of non-steroidal anti-inflammatory drugs (NSAIDS), such aspirin, ibuprofen and naproxen, by migraine sufferers could also explain some, but probably not all, of the reduction in breast cancer risk. A recent analysis of several studies showed a link between NSAID use and a 12 percent lower breast cancer risk. “Further work is needed to resolve what accounts for this relationship,” the researchers concluded.

Li added that women with migraines should “still have the same breast cancer screenings and follow-up,” and recommendation echoed by Dr. Michael Kraut, director of oncology at Providence Hospital in Southfield, Michigan. “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 also agrees that 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,” he said “This looks like one more piece of evidence that prolonged high levels of estrogen are dangerous.”

Li and team are now onto the next step—they are contacting women from the previous studies in hopes of learning more about the effects of different kinds of migraines. “We’re trying to understand what are the types of migraine that are most related to reduction in breast cancer risk,” Li says.

The study appears in the July issue of Cancer Epidemiology, Biomarkers and Prevention, a journal of the American Association for Cancer Research.

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