Antidepressants and colorectal cancer: A population-based nested case-control study

Background Experimental evidence indicates that serotonin is associated with both proliferative and pro-carcinogenic effects on colorectal tumors. The present study aims to investigate the associations between antidepressant use and colorectal cancer in an epidemiological sample. Methods We conducted a population-based case-control study utilizing Taiwan's National Health Insurance Research Database (NHIRD). We identified 49,342 cases with colorectal cancer and 240,985 controls between 1997 and 2008. We conducted conditional logistic regression analyses to assess the association between antidepressant use and colorectal cancer risk. Sensitivity analyses were conducted to assess whether genotoxic antidepressants (i.e. antidepressants which may exert procarcinogenic effects) would increase risk for colorectal cancer. Results Selective serotonin reuptake inhibitors (adjusted OR=1.00, 95% CI=0.94–1.06), tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors, and serotonin antagonist and reuptake inhibitors were not associated with increased incidence of colorectal cancer. Monoamine oxidase inhibitors were, however, associated with an increased incidence of colorectal cancer (adjusted OR=1.22, 95% CI=1.06–1.41). Higher cumulative dose of mirtazapine was associated with a decreased incidence of colorectal cancer (adjusted OR=0.39, 95% CI=0.17–0.90). A small sample size of individuals who received mirtazapine, however, precludes definitive conclusions regarding protective effects with mirtazapine. Limitations We could not discern the effects of obesity and other risk factors for colorectal cancer from the NHIRD. Conclusions Contemporary first-line antidepressants (i.e. SSRI, SNRI), as well as older agents (i.e. TCA), are not associated with increased incidence of colorectal cancer.