Background and Objectives: Hormonal replacement therapy (HRT) is effective in treating many debilitating symptoms of menopause. However, its use in women with uterine fibroids is widely debated, based on the susceptibility of these tumors to sexual steroids. This review aims to ascertain the effects of HRT on leiomyomas development and growth in postmenopausal women. Materials and Methods: Electronic databases (i.e., MEDLINE, Scopus, ClinicalTrials.gov, EMBASE, Sciencedirect, the Cochrane Library at the CENTRAL Register of Controlled Trials, Scielo) were searched from January 1990 until May 2019. All English-written studies evaluating the impact of various HRT regimens on uterine leiomyomas were selected. Results: Seventeen papers, considering a total of 1122 participants, were included. Fifteen of these were prospective trials, of which nine were randomized controlled trials. The remaining two works were a retrospective observational trial and a retrospective case series respectively. Five studies evaluated the effects of tibolone, also comparing it with various estrogen/progestin combinations, while two were about raloxifene. Thirteen studies compared different combinations of estrogens/progestins, the most common being transdermal estrogens (used in nine studies) and medroxyprogesterone acetate at different doses (used in 10 studies). Conclusions: For women with uterine fibroids, the choice of the most appropriate HRT regimen is crucial to avoid leiomyomas growth and the symptoms possibly related to it. Available data are conflicting, but suggest that uterine fibroids might be influenced by HRT, without representing an absolute contraindication to hormonal replacement therapy. Women with uterine fibroids subjected to HRT should be periodically examined and hormonal treatment should be discontinued if leiomyomas appear to increase in size. Moreover, the minimal effective dose of progestin should be employed.
Keywords: abnormal uterine bleeding; hormonal replacement therapy; menopause; postmenopausal women; uterine fibroids.