Objective: The objective of the study was to evaluate the endometrial safety of a 10 microg estradiol vaginal tablet in the treatment of vaginal atrophy in postmenopausal women.
Methods: A total of 336 healthy, non-hysterectomized, postmenopausal women (age 59.5 +/- 6.16 years, 9.4 +/- 5.9 years from last menses) were treated with a 10 microg estradiol vaginal tablet for 12 months (once daily for 2 weeks and then twice weekly for 50 weeks). Endometrial histology was analyzed at baseline and at the end of the trial.
Results: Of the 336 enrolled subjects, 292 (86.9%) completed the 52-week study. All 336 subjects received an endometrial biopsy at baseline, and 283 had biopsy results at week 52, when 258 out of the 283 biopsy samples were classified as 'atrophic' or 'inactive' endometrium. There were 21 with 'no tissue' despite a repeat biopsy attempt to obtain endometrial tissue, one had insufficient tissue with endometrial thickness >4 mm, one was 'weakly proliferative' and two revealed polyps. No cases of endometrial hyperplasia or endometrial cancer were reported. The mean endometrial thickness decreased from 2.04 mm (n = 334) from study start to 1.94 mm (n = 293) after 52 weeks, and the estradiol levels remained at the low postmenopausal level.
Conclusions: After 12 months of treatment with the 10 microg estradiol vaginal tablet, there was no suggestion of endometrial stimulation and no cases of endometrial hyperplasia or cancer reported. This study provides reassuring data on the endometrial safety of treatment with the 10 microg estradiol vaginal tablet for 1 year in a large group of postmenopausal, non-hysterectomized women with vaginal atrophy.