In the present study, we evaluated whether OCDO and its precursors can undergo a 27-hydroxylation in cancer cells expressing CYP27A1 and compared the proliferative properties of 27H-OCDO ((25R)-cholestane-6-oxo-3β,5α,26-triol) on ER(+) and TN BC cells with OCDO and 27HC. The gene discussed is CYP27A1; the disease is breast cancer.