The association between migraine and breast cancer risk: A systematic review and meta-analysis

Background: Migraines is likely to play a protective role in the risk of breast cancer. Some studies have shown that there is an inverse relationship between migraine and breast cancer, and some studies have not found an association; therefore, results from previous studies have been inconclusive and we conducted a meta-analysis to evaluate association between migraine and breast cancer. Methods: PubMed, EMBASE, Scopus and Web of Science were searched to identify studies on the association between migraine and breast cancer from January 1, 2000 through March 12, 2021. The pooled relative risk (RR) and the 95% confidence intervals (CI) was used to measure this relationship by assuming a random effects meta-analytic model. Results: A total of 10 studies were included. Our study revealed that there was statistically significant inverse relationship between migraine and breast cancer in case-control studies 0.68 [95% CI: 0.56, 0.82], but no significant relationship was found in cohort studies 0.98 [95% CI: 0.91, 1.06]. Also, migraine reduced the risk of ductal carcinoma 0.84 [95% CI: 0.73, 0.96], and lobular carcinoma 0.83 [95% CI: 0.73, 0.96]. With respect to ER_PR status no association between migraine and breast cancer was found. We found no evidence of publication bias. Conclusion: Our analysis demonstrated a statistically significantly inverse relationship between migraine and total risk of breast cancer only in case-control studies. In summary, cohort studies do not support an inverse association between migraine and incident breast cancer. While in case-control studies, migraine has an inverse association with ductal carcinoma and lobular carcinoma of breast.