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Published on: August 13, 2019
Endometrial effects of long-term treatment with phytoestrogens: a randomized, double-blind, placebo-controlled study
Vittorio Unfer1, Maria Luisa Casini, Loredana Costabile
1AGUNCO, Obstetrics and Gynecology Centre, Rome, Italy. vittorio.unfer@lycos.com
Objective:
To determine the effects of 5 years of treatment with soy phytoestrogens on histological characteristics of endometrium in postmenopausal women.
Design:
Randomized, double-blind, placebo-controlled study.
Setting:
Centre of Perinatal and Reproductive Medicine, Department of Gynecological, Obstetrical, and Pediatric Sciences, University of Perugia, Italy.
Patient(S):
Three hundred seventy-six postmenopausal healthy women, all with intact uterus.
Intervention(S):
Women were distributed in two different groups using randomized criteria: group A (n = 179) patients received soy tablets (150 mg of isoflavones per day) for 5 years; group B (n = 197) patients received identical appearing placebo tablets for 5 years.
Main Outcome Measure(S):
Results of endometrial histology from biopsies obtained at baseline, 30 months, and 5 years after the beginning of the treatment.
Result(S):
Two hundred ninety-eight women completed the 5-year treatment. No cases of malignancy were detected during biopsy. Seventy percent of women undergoing treatment with soy phytoestrogens had an endometrium classified as atrophic or nonassessable versus 81% receiving placebo. The occurrence of endometrial hyperplasia was significantly higher in group A (3.37% vs. 0%).
Conclusion(S):
Long-term treatment (up to 5 years) with soy phytoestrogens was associated with an increased occurrence of endometrial hyperplasia. These findings call into question the long-term safety of phytoestrogens with regard to the endometrium.