Through the haze of the severe symptoms migraine patients experience shines a new light of the possibility of protection from a deadly cancer. Scientists have recently found that women with migraines may recognize a 26% lower risk in developing breast cancer (odds ratio, 0.74; 95% confidence interval, 0.66-0.82), compared with women with no history of migraine (Cancer Epidemiology, Biomarkers & Prevention, July 2009).
Christopher I. Li, MD, PhD, an associate member of the epidemiology department at the Fred Hutchinson Cancer Research Center, and colleagues studied data from 4568 women with breast cancer and 4678 control patients in the Women’s Contraceptive and Reproductive Experiences Study. The participants—recruited from the 5 metropolitan areas of Atlanta, Detroit, Los Angeles, Philadelphia, and Seattle—were between the ages of 35 and 64 and were diagnosed with invasive breast cancer between 1994 and 1998. For the study, women were asked if “a doctor or other health professional ever told you that you had migraine headaches,” their age at the time of migraine diagnosis, and if they ever used prescription medication for migraine. Information was also collected on breast cancer risk factors, such as reproductive history, anthropometric characteristics, use of exogenous hormones, family history of breast cancer, and lifestyle characteristics. The risk of developing breast cancer was not affected by age at migraine diagnosis; race; premenopausal or postmenopausal status; or by the history of ever using migraine medications.
Li and colleagues theorized that the link between migraines and breast cancer may be due, in part, to the fact that patients with migraines more frequently use nonsteroidal anti-inflammatory drugs (NSAIDs), and these medications have been linked with a reduced risk of breast cancer. This only partly explains the relationship, however—a recent study of NSAID use and breast cancer risk only showed a 12% reduction in risk for women who ever used an NSAID—much lower than the 26% reduction in risk for women with migraine.
The researchers believe that the biological reasoning for the link between a history of migraine and a reduced breast cancer risk may be that both diseases are hormonally mediated. “Many triggers for migraine are also things that reduce estrogen levels,” stated Li, and many breast cancers are fueled by estrogen.
This study supports the findings of a previous study (Cancer Epidemiology, Biomarkers & Prevention, November 2008) that found that postmenopausal women with a history of migraine had a 33% lower risk of invasive ductal breast cancer and a 32% lower risk of invasive lobular breast cancer, compared with women without such history. Although the study sheds some new light onto the relationship between migraines and breast cancer risk, the authors of the study concluded that further research is needed to determine the exact source of the link.