ESR1 and breast cancer: Molecular mechanisms involved in the anticancer effect of polyphenols in relation to breast cancer include interference with redox balance (acting either as antioxidant or pro-oxidant, they exert chemopreventive and antitumoral effects, respectively), cell cycle arrest, pro-apoptotic, autophagy activation, anti-inflammatory effect (inhibition of NF-kB, COX-2, and LOX), antiestrogenic effect, changes in ER expression, aromatase modulation, and interference with HER2 signaling (14).