In 2008, a study indicated that women with Migraine disease have a 30% lower risk of developing breast cancer. At that time, lead researcher Christopher Li said,
"We found that, overall, women who had a history of Migraines had a 30 percent lower risk of breast cancer compared to women who did not have a history of such headaches... Women who have higher levels of estrogen in their blood have higher levels of breast cancer."
Many people (including me) were reluctant to accept the results of this study for a number of reasons. Now, the original researchers, joined by several more, have published a second paper on the relationship between Migraine history and breast cancer risk.
The new study
Data was analyzed from the Women’s Contraceptive and Reproductive Experiences Study, a population-based case-control study of women ages 35 to 64 years diagnosed with invasive breast cancer between 1994 to 1998 from five major metropolitan areas: Atlanta, Detroit, Los Angeles, Philadelphia, and Seattle. Of 5,982 eligible participants, 4,575 (77%) were enrolled and interviewed. Female control participants without breast cancer in the same areas were identified and frequency matched to cases on 5-year age group, race, and study site. Of the 5,956 eligible control participants, 4,682 (79%) were enrolled and interviewed. Seven participants with breast cancer and four control participants with an unknown history of migraine were excluded from all analyses leaving a total of 4,568 cases and 4,678 controls. Those in the breast cancer are referred to as "cases;" those in the group without are referred to as "controls.
- Cases were somewhat more likely than controls to have had a natural menopause and to be using combined estrogen and progestin hormone therapy (CHT). Otherwise, cases and controls were comparable.
- Women who had a diagnosis of Migraine had a risk of breast cancer reduced by 26% over women with no history of Migraine.
- Age at Migraine diagnosis did not impact breast cancer risk.
- History of having used prescription Migraine medications did not impact breast cancer risk.
The relationship between Migraine and reduced breast cancer risk was similar among
- both premenopausal and postmenopausal women;
- black women and white women;
- women who drank alcohol and women who didn't;
- women who used oral contraceptives and women who didn't.