Could there be an upside to the misery of migraines? Yes, say researchers from Washington state, who found an apparent association between hormone-related migraines and reduced incidence for breast cancer.
The researchers studied nearly 2,000 post-menopausal women with invasive breast cancer and about 1,500 post-menopausal women with no history of breast cancer. Those with a clinical diagnosis of migraines at some point in their lifetime had a one-third lower risk of breast cancer, particularly the hormone-receptor positive breast cancers, which are the most common forms of the disease.
Overall, women suffer from migraines at two to three times the rate of men. The problem is more common and more severe in pre-menopausal women, who tend to get migraines when estrogen levels fall, just before or during menstruation and during the hormone-free week of oral contraceptive use. It’s not clear why falling estrogen levels cause migraines in some women and not others, but the researchers think that women who suffer from migraines may be more sensitive to estrogen fluctuations or experience them in a different way.
In a seeming paradox, many women experience a dramatic decrease in migraines after menopause when estrogen levels remain consistently low. With migraine, it seems that a steady rate of estrogen — high or low — can be protective, says study coauthor Christopher Li, MD, PhD, a breast cancer epidemiologist at the Fred Hutchinson Cancer Research Center in Seattle. “In many women, migraines are triggered by changes in hormone levels since the frequency of migraines increases when hormone levels rise or fall and decreases when hormone levels are at a steady state,” he explained. Dr. Li says this may be due to the fact that estrogen affects the production of the neurotransmitter serotonin, which then prevents the release of peptides involved in inflammation and pain.
Since higher levels of estrogen and its metabolites may stimulate the growth of hormonally sensitive breast cancer, it makes sense that declining estrogen may protect against the disease. Although the study focused only on invasive breast cancers, Dr. Li believes the hypothesis applies to non-invasive forms of the disease as well.
One theory postulates that NSAIDs (non-steroidal anti-inflammatory drugs), commonly taken to treat migraines, may be partly responsible for the reduced breast cancer risk, thanks to their anti-inflammatory properties. However, other research indicates it’s unlikely that these drugs account for the entire reduction. Dr. Li hopes this study contributes to a greater understanding of the effect that pre-menopausal hormones can have on the risk of developing breast cancer after menopause. “We don’t have a lot of factors that reduce breast cancer risk — the migraine-hormone connection might be one of them,” he says.