Previous studies have provided evidence for potential mechanisms underlying the racial disparity in tumor development and progression including polymorphism of the genes COMT, ER (estrogen receptor), and CYP17 (cytochrome P450C17α) which are involved in estrogen synthesis, function and/or metabolism, and the upregulation of aromatase (CYP19) gene in tumors of African American women as compared with Caucasians [6, 79]. Here, ESR1 is linked to neoplasm.