Psychotropic medication use and postmenopausal breast cancer risk.

Background: Prior studies evaluating psychotropic medications in relation to breast cancer risk are inconsistent and have not separately evaluated invasive and in situ disease. Methods: We estimated hazard ratios (HR) and 95% confidence intervals (CI) for the association of psychotropic medication use (any, typical antipsychotics, atypical antipsychotics, and lithium) with invasive and in situ breast cancer risk among Women's Health Initiative participants (N = 155,737). Results: Prevalence of psychotropic medication use was low (n = 642; 0.4%). During an average 14.8 (SD, 6.5) years of follow-up, 10,067 invasive and 2,285 in situ breast tissues were diagnosed. Any psychotropic medication use was not associated with invasive breast cancer risk compared with nonusers (HR, 0.82; 95% CI, 0.57-1.18). In situ breast cancer risk was higher among "typical" antipsychotic medication users compared with nonusers (HR, 2.05; 95% CI, 0.97-4.30). Conclusions: These findings do not support an association of psychotropic medication use with invasive breast cancer risk. The possible elevation in in situ breast cancer risk associated with "typical" antipsychotics could not be explained by differences in screening mammography utilization and merits further study. Impact: Our findings contribute to knowledge of the safety profile of psychotropic medications and may be useful to clinicians and patients considering use of these medications.