Twenty-three out of 25 patients showed high expression of SFRP1 mRNA in leiomyoma than the matched normal myometrium.  During the menstrual cycle, the level of SFRP1 mRNA in leiomyoma was highest in the follicular phase.  Gonadotropin releasing hormone analogue (GnRHa) decreases estrogen secretion from the ovary. Patients treated with (GnRHa) presurgically showed the lowest expression of SFRP1 in both myometrial and leiomyoma tissues.  These findings suggest that SFRP1 could be under the control of estrogen.  Gene expression of estrogen receptors in leiomyomas is stronger than that in the myometrium.  This suggests that leiomyoma possess increased sensitivity to E2 (estradiol, a form of estrogen) and the estrogen-dependent expression of SFRP1 in leiomyoma could be associated with the growth and pathogenesis of leiomyoma.