Antidepressant use and breast cancer risk

Background. Antidepressants are among the most commonly prescribed drugs in the United States. Laboratory studies suggest that because certain antidepressants increase prolactin levels that they may also increase breast cancer risk. However, human studies evaluating use of antidepressants in relation to breast cancer risk have yielded inconsistent results. Methods. A population-based case-control study consisting of 975 breast cancer cases 65-79 years of age diagnosed from 1997-1999 and 1007 age and residence-matched controls was conducted in western Washington State. Detailed information on antidepressant use was obtained through structured in-person interviews. Logistic regression was performed to analyze the relationship between antidepressant use and breast cancer risk. Results. Overall, there was no association between ever use of antidepressants and breast cancer risk (odds ratio [OR] = 1.2, 95% confidence interval [95% CI]: 0.9-1.6). When evaluated separately, tricyclic antidepressants (TCA), selective serotonin reuptake inhibitors (SSRI), and triazolopyridines were each not associated with breast cancer risk. However, risk varied by hormone receptor status. Compared to never users, ever users of SSRIs had elevated risks of progesterone receptor (PR) negative and estrogen receptor (ER) positive/PR-negative breast cancers (OR = 1.8, 95% CI: 1.1-3.6 and OR = 2.0, 95% CI: 1. 1-3.8, respectively), but not of tumors with other hormone receptor profiles. Conclusions. Based on these results and those of previous studies, there is limited evidence that any type of antidepressant use is associated with breast cancer risk overall. SSRIs may elevate risks of PR- and ER+/PR-tumors, though further studies are needed to confirm these associations.