On a genetic level, a comparable study in a set of 20 paired samples of tumour and adjacent normal breast tissues from patients with infiltrating ductal carcinoma identified the expression of CYP1B1, CYP2B6, CYP2C, CYP2D6, CYP2E1, CYP4B1 and CYP11A1 in both tumour and control tissues [15]. This evidence concerns the gene CYP2D6 and neoplasm.