Endometrial effects of a tissue selective estrogen complex containing bazedoxifene/conjugated estrogens as a menopausal therapy

ObjectiveTo evaluate the endometrial safety of a tissue selective estrogen complex (TSEC; pairing of a selective estrogen receptor modulator [SERM] with estrogens) composed of bazedoxifene/conjugated estrogens (BZA/CE) in postmenopausal women.DesignRandomized, double-blind, multicenter, placebo- and active-controlled, phase 3 study (Selective estrogen Menopause And Response to Therapy [SMART]-1).SettingOutpatient clinical.Patient(s)Healthy, postmenopausal women (n = 3,397) age 40–75 with an intact uterus.Intervention(s)Single tablets of BZA (10, 20, or 40 mg) combined with CE (0.625 or 0.45 mg); raloxifene (60 mg); or placebo daily for 2 years.Main Outcome Measure(s)Incidence of endometrial hyperplasia at 12 months in the efficacy evaluable population.Result(s)Treatment with BZA (20 or 40 mg)/CE (0.625 or 0.45 mg) was associated with low rates (<1%) of endometrial hyperplasia that were not significantly different from those reported with placebo over 24 months. Endometrial thickness with BZA (20 or 40 mg)/CE (0.625 or 0.45 mg) was not significantly different from that with placebo.Conclusion(s)When combined with CE (0.625 mg or 0.45 mg), BZA (20 mg) was the lowest effective dose that prevented endometrial hyperplasia over 2 years of study, creating the possibility for a new, progestin-free menopausal therapy.