Endometrial histology following 1 year of a continuous daily regimen of levonorgestrel 90 μg/ethinyl estradiol 20 μg

ObjectiveThe objective of this study was to evaluate the effect of a continuous daily regimen of levonorgestrel (LNG) 90 μg/ethinyl estradiol (EE) 20 μg on endometrial histology.MethodsThis was a substudy of a large phase 3 trial conducted in six sites in North America. Healthy and sexually active women aged between 18 and 49 years took LNG 90 μg/EE 20 μg daily for 1 year. Results from endometrial biopsies performed at pretreatment baseline and those after at least 6 months of treatment were compared.ResultsOf the 146 participants, 93 had a baseline biopsy and completed at least six pill packs. Before treatment, 56 subjects (60%) had an endometrial biopsy with findings classified as “weakly proliferative or proliferative.” During the last on-therapy visit, 48 subjects (52%) had an endometrium categorized as “other,” which included primarily an inactive or benign endometrium (n=42). No hyperplasia or malignancy was observed during the study.ConclusionThe results of a 1-year continuous regimen of LNG 90 μg/EE 20 μg were shown to have a good endometrial safety profile.