Notably, the CRC subtypes had obvious overlap with the known molecular subtypes of breast cancer defined by the expression of estrogen receptor (ER) or progesterone receptor (PR) and human epidermal growth factor receptor 2 (Her2) including ER/PR+, Her2+; ER/PR+, Her2−; ER/PR−, Her2+; and ER/PR−, Her2−. This evidence concerns the gene ESR1 and breast carcinoma.