Tamoxifen, a selective estrogen receptor modulator, is known to reduce the risk of recurrence of breast cancer in women with hormone receptor-positive tumors. This study aims to evaluate the differences in mortality between women concomitantly treated with tamoxifen and selective serotonin reuptake inhibitors (SSRIs).

This population-based cohort study included two cohorts: cohort A contained 6,067 women who started taking an SSRI during tamoxifen treatment; cohort B contained 8,465 women who were already taking an SSRI when they started taking tamoxifen. The primary outcome of the study was all-cause mortality in each cohort measured using propensity scores and hazard ratios.

During a median follow-up of 2.2 years, 991 deaths occurred in cohort A, and 1,014 deaths occurred in cohort B. The rate of mortality was 58.6 per 1,000 person-years for potent inhibitors and 57.9 per 1,000 person-years for SSRIs; the pooled hazard ratio for death for the two groups was 0.96. The findings also confirmed that the results were consistent across all sensitivity analyses.

The research concluded that the concomitant use of tamoxifen and potent CYP2D6 inhibiting SSRIs was not associated with an increased risk of mortality when compared with other SSRIs.

Ref: https://www.bmj.com/content/354/bmj.i5014