| Background. Antidepressant use has increased dramatically since the introduction of selective serotonin reuptake inhibitors (SSRIs). Initial concern about a role of antidepressants in breast carcinogenesis was sparked by reports of an increased occurrence of mammary tumors in rats administered tricyclic antidepressants or SSRIs. Epidemiologic findings have been inconsistent, varying by individual drug, class of drug, timing of use, and method of ascertaining antidepressant exposure.; Aims. To determine if users of antidepressant medications overall, specific classes of antidepressants, or individual antidepressant medications are association with an increased risk of breast cancer.; Methods. We conducted a population-based case-control study among women enrolled in Group Health Cooperative (GHC). Women with a first primary breast cancer diagnosed between 1990 and 2001 were identified (N = 2904). Five controls were selected for each case (N = 14396). Antidepressant use was ascertained through the GHC pharmacy database. Information on factors known to influence breast cancer risk was obtained from existing computerized records. Odds ratios and 95% confidence intervals were estimated using unconditional logistic regression adjusting for matching factors (age, length of GHC enrollment, and calendar year), body mass index, family history of breast cancer, duration of use of hormone replacement therapy, parity/age at first birth, and history of a screening mammogram within two years.; Results. About 20% of cases and controls had used tricyclic antidepressants and 6% had used SSRIs. Neither use of antidepressants overall, nor tricyclics, SSRIs, or atypical antidepressants considered separately were associated with an increased risk of invasive breast cancer. Risk did not increase with a greater number of prescriptions filled. Risks did not vary by timing of use or when stratified by age (<50, >= 50). When individual drugs were examined the risk associated with one tricyclic antidepressant (amitriptyline) was slightly elevated (OR = 1.27, 95% CI 1.10--1.47), but other studies that have examined individual tricyclic medications observed no increased risks associated with the use of this drug.; Conclusions. Taken as a whole, the results from this and other studies do not provide compelling evidence for an increased risk of breast cancer associated with the use of antidepressants overall, by class of drug, or for individual antidepressants. |
