November 7, 2008 — Women with a history of migraine had a 30% lower risk for breast cancer, a new study shows. For the first time, investigators have linked migraines with breast cancer risk, and they suggest that women with headaches have lower cancer rates — especially estrogen- and progesterone-receptor–positive ductal and lobular carcinomas.
The biologic mechanism behind the association is not known, but the research team suspects that it has to do with fluctuations in levels of circulating hormones. Their work appears in the November issue of Cancer Epidemiology, Biomarkers & Prevention.
“These are preliminary results and should be interpreted with caution,” senior investigator Christopher Li, MD, from the School of Public Health and Community Medicine at the University of Washington, in Seattle, told Medscape Neurology & Neurosurgery. “But this is potentially good news for women with migraines.”
Dr. Li emphasized the fact that no changes to screening are recommended at this time. “If these findings can be replicated in other populations,” he added, “we may acquire new insights into the pathogenesis of breast cancer.”
Possibly Due to Fluctuating Hormone Levels
Dr. Li’s team combined data from 2 population-based case-control studies of more than 3400 postmenopausal women. Of these, 1938 had been diagnosed with breast cancer and 1474 had no history of cancer.
The investigators, led by Robert Mathes, PhD, also from the School of Public Health and Community Medicine at the University of Washington, obtained information on migraine history by self-report and limited their study population to cases that had been diagnosed by a physician or other health professional.
The researchers found that women who reported a clinical diagnosis of migraine had a reduced risk for ductal carcinoma (odds ratio [OR], 0.67; 95% confidence interval [CI], 0.54 – 0.82) and lobular carcinoma (OR, 0.68; 95% CI, 0.52 – 0.90).
Investigators observed reductions in risk among migraine sufferers who did and did not use prescription medications for their headaches.
Relationship Between Migraine and Breast Cancer
|Migraine Status||Controls, n=1474 (%)||Ductal Carcinoma, n=1199 (%)||Lobular
Carcinoma, n=739 (%)
|Use of prescription migraine drugs|
An estimated 15% to 18% of women in the United States have migraines. The prevalence of migraine in women is roughly 2 to 3 times higher than in men. The frequency of migraine headaches tends to change at various times in a woman’s reproductive cycles and may be due to fluctuating estrogen levels.
“Given these observations and the well-established positive association between endogenous circulating hormone levels and risk of hormone-receptor–positive breast cancer, we hypothesized that migraine may be particularly associated with a reduced risk of hormone-receptor–positive tumors,” the researchers write.
But the group cautions that it is also possible that medications used to treat or prevent migraine, rather than the occurrence of migraines, may be responsible for the reductions in risk.
“Several studies of nonsteroidal anti-inflammatory drugs [NSAIDs] have shown that NSAID use is associated with a reduced risk of breast cancer — especially hormone-receptor–positive tumors,” the researchers write.
Dr. Li pointed to a number of limitations to the current study. He noted that information on migraine history was based on self-report and could have been subject to bias. There were also few data on migraine characteristics, particularly their relation to the menstrual period and other reproductive events.
“While these results need to be interpreted with caution, they point to a possible new factor that may be related to breast cancer risk,” Dr. Li added in a news release. “This gives us a new avenue to explore the biology behind risk reduction. Hopefully, this will help stimulate other ideas and extend what we know about the biology of the disease.”
This study was funded by the National Cancer Institute through contracts with the Fred Hutchinson Cancer Research Center. Coauthor Sylvia Lucas, MD, from the department of neurology at the University of Washington Medical Center, in Seattle, reports having financial ties to GlaxoSmithKline, Merck, Pfizer, and Ortho-McNeil. The other authors have disclosed no relevant financial relationships.
Cancer Epidemiol Biomarkers Prev. 2008;17:3116-3122. Abstract