CYP27A1 metabolises cholesterol to the ER + breast cancer oncometabolite 26-HC, but CYP27A1 also provides a deactivation rout for 3β,5α,6β-triol diverting its metabolism from the oncometabolite 3β,5α-diHC-6O to bile acid biosynthesis. This evidence concerns the gene CYP27A1 and breast carcinoma.