Isoflavones interfere with ERα and ERβ isoforms with higher binding affinity for the latter, particularly genistein (20- to 30-fold higher) and daidzein (five-fold) [19] (Table 1), producing distinct clinical effects from estrogens and contributing to the treatment of various cancers, such as gastric, breast, prostate, and non-small cell lung cancer prostate cancer [136,144,145,146]. Here, ESR1 is linked to cancer.