Long-term endometrial and breast safety of a specific, standardized soy extract

Objective To assess the effects of an oral soy isoflavone extract (Phytosoya®) on endometrium and breast in postmenopausal women treated for 3 years.Methods A total of 395 postmenopausal women were included in this international prospective, open-label study. The number of patients who completed the 3-year study was 197. The women were treated for 3 years with a specific, standardized soy isoflavone extract (total 70 mg/day). Endometrial biopsy, transvaginal ultrasonography and mammography were performed before and after 3 years of treatment.Results No case of hyperplasia/cancer was diagnosed among the 192 interpretable biopsies at 3 years. Only one case of simple hyperplasia was diagnosed among 197 post-baseline interpretable biopsies. The endometrial safety of this extract has been demonstrated (point estimate 0.5%). There was no statistically significant change in endometrial thickness after 3 years (98.4% inactive or atrophic and 0.3% proliferative endometrium at 1 year). Mammography results showed no...