Depression and Antidepressant Use in Relation to Breast Cancer Risk in the Nurses Health Study

Abstract

Abstract Depression and antidepressant (AD) use have each been hypothesized to increase breast cancer risk, yet previous studies have not considered these exposures together. Thus, it is unclear whether increased risk due to depression may actually be attributable to AD use, or vice versa. Methods: We utilized data from 77,482 women enrolled in the prospective Nurses' Health Study cohort in which data on depression and AD use were collected simultaneously beginning in 2000. Women self-reported whether they had ever been diagnosed with depression by a clinician as well as their use of specific types of ADs. Self-reported breast cancer cases through 2012 were adjudicated and only confirmed invasive cases included as outcomes (N = 2,567). Logistic regression models were utilized to evaluate the effects of baseline depression and AD use, both independently and with mutual adjustment, on breast cancer risk. Results: The average age of participants was 66.2 (SD 7.1) years; 8.9% were clinically depressed and 8.7% used ADs. In separate models adjusted for age, body mass index, and menopausal status, we observed no statistically significant associations between depression (OR 0.94, 95% CI, 0.81–1.08) or AD use (OR 1.07, 95% CI, 0.93–1.22). When these exposures were included together in the same model, depression remained unassociated with breast cancer risk (OR 0.87, 95% CI, 0.74–1.03) while AD use exhibited a small, borderline significant increase in risk (OR 1.15, 95% CI, 0.98–1.35). The latter association remained consistent for selective serotonin reuptake inhibitors (SSRIs; OR 1.16, 95% CI, 0.96–1.39) but was not apparent for other classes of ADs (OR 1.07, 95% CI, 0.85–1.35). Conclusions: These initial results indicate that depression is not associated with breast cancer risk, while we could not exclude a slight increase in risk associated with SSRI use. Further analyses will update exposure information over follow-up and also evaluate whether associations differ by menopausal status or hormone receptor disease subtypes. Clarifying the effects of these exposures on breast cancer risk will provide critical information for the millions of women who are depressed and/or use ADs.