(RxWiki News) They're painful and can put patients out of commission for hours or even days, but migraines aren't likely associated with breast cancer — despite past research that suggested they might be.
In a new study, women with migraines were not more likely to have breast cancer than those without migraines.
The authors of this new study also didn't find a connection between migraines and female sex hormones, which health professionals have thought might be associated with migraines. Past studies showed inconsistent results in migraine-breast cancer connections.
“In summary, results from this large ... study do not support an inverse association between migraine and incident breast cancer," wrote the study authors, led by Rulla M. Tamimi, ScD, of Brigham and Women's Hospital and Harvard Medical School in Boston. "In addition, women with migraine do not have different premenopausal ... sex hormone levels compared with women without migraine.”
Migraines, which can cause debilitating headaches, nausea and vomiting, are more common in women than men. What exactly causes migraines is unknown. Research on migraines and breast cancer has turned up inconsistent findings, but some research had indicated a possible link between migraines and breast cancer. Researchers theorized the connection could be based on female sex hormones, especially estrogen.
Dr. Tamimi and team used data from a large, ongoing research project called the Nurses’ Health Study II (NHSII). The NHSII provided data over a 20-year period on 115,378 women. Those women were 25 to 42 years old when the study began.
Of the women in the study, 17,696 said a doctor had diagnosed them with migraines. Dr. Tamimi and colleagues had access to data from the NHSII that included hormone levels in women who had not yet reached menopause. They reviewed medical records from 90 percent of the women who developed breast cancer during the 20 years of the NHSII study.
The team found that 3,924 women had been diagnosed with breast cancer. Of these, 833 had in situ cancer — cancer which had not spread beyond the breast tissue. The remaining 3,091 had invasive cancer, which had spread from the original site.
Dr. Tamimi and colleagues found that migraines did not increase the risk of breast cancer — with one exception. Women who had migraines were 1.54 times more likely to develop a type of cancer called ductal-lobular breast cancer than other types of cancer.
These researchers did not find a link between female sex hormones, migraines and breast cancer.
After completing their own study, Dr. Tamimi and team looked at four past studies on the same subject, as well as their own — a process called a meta-analysis. They looked for connections between migraines, breast cancer, and female sex hormones like estrogen and progesterone. This meta-analysis did not find a link between migraines and breast cancer.
This study was published Dec. 12 in the Journal of the National Cancer Institute.
This research was funded by grants from the National Institutes of Health (NIH) and by funds from Washington University School of Medicine, the Barnes-Jewish Hospital Foundation and the Siteman Cancer Center.
Dr. Tobias Kurth received research funding from the French National Research Agency, the NIH, Merck, the Migraine Research Foundation and the Parkinson’s Disease Foundation. He received honoraria from Allergan and the American Academy of Neurology for educational lectures, and from the BMJ and Cephalalgia for editorial services. Dr. Tamimi was a consultant and advisory board member for Pfizer. Some of these companies produce medications used in migraine and breast cancer treatment.