However, the impact of CYP2D6 genotype on tamoxifen efficacy was evaluated in 95 patients as two patients were excluded; one patient presented with non-invasive breast cancer (Paget’s disease) and the other was concurrently on a strong CYP2D6 inhibitor (fluoxetine) as depicted in Fig. 1. This evidence concerns the gene CYP2D6 and breast carcinoma.