Interestingly, thirteen core ADME genes (ABCB1, ABCC2, ABCG2, CYP2D6, CYP2E1, CYP3A5, DPYD, GSTP1, GSTT1, NAT1, SLC15A2, SULT1A1, TPMT) were expressed in all 21 cancer types. This evidence concerns the gene CYP2D6 and cancer.