It had been documented that icaritin exhibited estrogen-like activity in estrogen receptor-positive breast cancer MCF-7 cells at sub-micromolar concentration [11]; while at micromolar levels, icaritin might inhibit the growth of prostate cancer PC-3 cells [12], and suggesting icaritin may function as an estrogen receptor modulator in regulating cell growth. This evidence concerns the gene ESR1 and Familial prostate cancer.