Objective: The aim of this study was to evaluate the long-term endometrial safety of long-cycle sequential oestrogenprogestogen hormone replacement therapy (HRT).
Study design: A prospective, longitudinal, single group study was undertaken in postmenopausal women, aged 45-66 years, treated with up to 21 3-month cycles (five years) of sequential oestrogen-progestogen HRT. Treatment consisted of 70 days of 2 mg/day oestradiol valerate (E2V), followed by 14 days of E2V combined with 20 mg/day medroxyprogesterone acetate (MPA), followed by seven days placebo.
Endometrial biopsies were assessed at baseline, at 12 months in women with an endometrial thickness >6 mm and in all participants at 24, 36, 48 and 60 months. Mammography was performed at baseline and at 24-month intervals thereafter. Adverse events were assessed throughout the study.
Results: Of 132 women enrolled, 94 completed five years of treatment (540 women years). Endometrial changes (oestrogen effect II) were apparent in most women from 24-60 months (95, 83.3% women at 24 months). One case of simple hyperplasia was found (at 60 months), and none of complex hyperplasia or endometrial cancer. The pattern and frequency of adverse events were consistent with other sequential oestrogen-progestogen HRT regimens.
Conclusions: The incidence of hyperplasia over five years (0.19%, upper 95% CI 0.88) was well within the acceptable rates defined by the European Union Committee for Proprietary Medicinal Products (CPMP).
