As regards breast cancer chemoprevention, mechanism of action of SFN is multidirectional and includes e.g., increased levels of detoxification enzymes, decreased enzymatic activity of P450 cytochrome (CYP1A1, CYP1A2), reduced cancer cell viability/proliferation through inhibition of cell cycle, induction of apoptosis and autophagy as well as elimination of cancer stem cells (CSCs). This evidence concerns the gene CYP1A2 and breast cancer.