The keywords for the literature search were the following: colon/colorectal cancer, female sex steroid hormones, therapeutic potential effect/molecular mechanisms of estrogen, estradiol, estrogen receptor, progesterone, progesterone receptor, endogenous expression of estrogen receptor, endogenous expression of progesterone receptor, in vitro human male and female CRC cell lines, and in vivo CRC animal models. The gene discussed is ESR1; the disease is colorectal cancer.