Tamoxifen and SSRIs

The latest observational study to assess whether SSRIs and other drugs that inhibit CYP2D6 hepatic enzymes reduce the efficacy of tamoxifen has found no significant effect (J Clin Oncol 2010;28:2423-9).

    However, the study did show that reduced adherence to tamoxifen treatment was associated with increased risk.
    The finding conflicts with earlier evidence that CYP2D6 inhibitors may be associated with a two-fold increase risk of breast cancer recurrence in women using tamoxifen and the authors advise continuing caution. Guidance on the use of CYP2D6 inhibitors and tamoxifen was recently published (J Clin Oncol 2010; published online doi: 10.1200/JCO.2009.23. 8931).