The risk of breast cancer associated with specific patterns of migraine history

Studies have suggested that a history of migraines may be associated with a lower risk of some types of breast cancer, though biological mechanisms are unclear. Identifying specific characteristics of migraines which are most strongly associated with breast cancer risk could improve our understanding of this relationship. We ascertained specific characteristics of women's migraine histories (severity, timing features, and presence of migraine aura). We used polytomous logistic regression to estimate the risk of ER+ ductal, ER- ductal, ER+ lobular, and ER+ ductal-lobular breast cancer associated with self-reported characteristics of migraine history. A total of 715 breast cancer cases (276 ER+ ductal, 46 ER- ductal, 191 ER+ lobular, and 202 ER+ ductal-lobular) and 376 controls ages 55-74 years were included in this population-based case-control study. Compared to women without a migraine history, women with a > 30-year history of migraines had a 60 % (95 % CI 0.2-0.6) lower risk of ER+ ductal breast cancer; those who had their first migraine before age 20 had 50 % lower risks of ER+ ductal and ER+ lobular breast cancer (both 95 % CIs 0.3-0.9), and women who experienced migraine with aura had 30 % (95 % CI 0.5-0.98) and 40 % (95 % CI 0.4-0.9) lower risks of ER+ ductal and ER+ lobular breast cancer, respectively. The lower risk of ER+ breast cancer associated with migraine appears to be limited to those women with early onset or long duration of migraine history, or those who experienced migraine with aura. This expands our understanding of the relationship between migraine and breast cancer and provides additional insight into potential underlying biological mechanisms.