SSRI use and breast cancer risk by hormone receptor status

Background There is little evidence linking the use of selective serotonin reuptake inhibitors (SSRIs) with increased breast cancer risk, but one study has found an association with estrogen receptor negative (ER-) and progesterone receptor negative (PR-) tumors. Methods We used data collected on 820 invasive breast cancer cases and 2852 hospitalized controls collected from 1990 through 2006. Information on medication use and other variables was collected by nurse interviewers. We used unconditional logistic regression analyses to evaluate the association between regular SSRI use (use at least 4 times/week for at least 3 months) and breast cancer risk overall and by subtype defined by hormone receptor status. Results The odds ratio for all breast cancer was not elevated among regular users of SSRIs (OR = 0.89, 95% CI 0.62-1.29). None of the odds ratios varied from 1.0 in any category of hormone receptor status. Among women aged 55 and over, the odds ratios were increased for ER- (OR = 1.84, 95% CI 0.66-5.16), PR- (OR = 1.85, 95% CI 0.80-4.27), and ER-PR- (OR = 2.10, 95% CI 0.73-6.02) tumors, but these estimates were compatible with chance. Conclusion We found no association between SSRI use and breast cancer risk, overall or by hormone receptor status. Odds ratios were elevated in older women, particularly for ER- and PR- tumors, but the confidence intervals were compatible with no association.