Antidepressant use and risk of central nervous system metastasis.

Selective serotonin reuptake inhibitors (SSRIs), a class of antidepressants, were found to increase central nervous system (CNS) metastasis in mice. Our study investigated in humans whether antidepressants, and specifically SSRIs, increased the relative odds of CNS metastasis. We identified 189 cases of CNS metastasis amongst breast cancer, melanoma, and non-Hodgkin lymphoma subjects who were diagnosed with CNS metastasis or infiltration between January 1, 2005 and September 30, 2013 and 756 controls (patients without CNS metastasis or infiltration). Using logistic regression, we estimated the relative odds of CNS metastasis associated with antidepressant use adjusting for relevant covariates. The prevalence of antidepressants was 28.6 % in cases and 27.5 % in controls, whereas SSRIs were used in 16.9 % of cases and 17.3 % of controls. Among all patients, antidepressants were not associated with CNS metastasis or infiltration. No consistent patterns of association were observed in the analyses of other cancer subsets or exposure measures, with the possible exception of an increased risk of CNS metastasis associated with 'any SSRI use' among breast cancer patients (OR = 1.73, 95 % CI = 0.75, 4.04). We did not observe clear patterns of association, which may be due in part to the small sample size in many of our analyses.