Since GnRHa administration negatively regulates the production of estrogen/progesterone, which leads to a reduction in myoma size, the expression of estrogen receptor (ER) and progesterone receptor (PR) are up-regulated in leiomyoma by a negative feedback mechanism; this is consistent with what was published in previous reports18,19 and in the current study. This evidence concerns the gene ESR1 and leiomyoma.