Effect of Steroid Add-back Therapy on the Proliferative Activity of Uterine Leiomyoma Cells Under Gonadotropin-releasing Hormone Agonist Therapy

Short-term treatment with gonadotropin-releasing hormone agonist (GnRHa) is a useful preoperative medical therapy of uterine leiomyomas. However, adverse effects caused by the hypo-estrogen state sometimes appear, suggesting the necessity of add-back therapy. In this study, we investigated effects of three kinds of add-back therapies on the proliferative activity of uterine leiomyoma cells by examining the expression of Ki-67 in leiomyoma cells by immunostaining. Thirty patients who were to undergo hysterectomy or myomectomy were injected with 3.75 mg depot leuprolide acetate every four weeks until the end of the 12th week. Twenty patients underwent add-back therapy from the 5th week to the end of the 12th week, 8 patients receiving 0.625 mg of conjugated equine estrogen (CEE) /day, 6 patients 5.0 mg of medroxyprogesterone acetate (MPA)/day, 6 patients 0.625 mg CEE plus 2.5 mg of MPA /day. The add-back of CEE or CEE plus MPA suppressed decreases in the proliferative activity of leiomyoma cells caused by GnRHa therapy, but that of MPA did not. These results suggest that the add-back therapy with MPA is of use in preventing the adverse effects caused by hypo-estrogen in the preoperative short-term GnRHa therapy.