title: Endometrial effects of tibolone in elderly, osteoporotic women.
abstract: OBJECTIVE
  To investigate endometrial effects of tibolone administered to postmenopausal women for 3 years.
  
  
  METHODS
  Postmenopausal women (N=3,519) aged 60-85 years (mean 68 years) with a uterus and with osteoporosis were randomly assigned to receive tibolone orally, 1.25 mg per day, or identical placebo. We evaluated effects on endometrial thickness in all women, and examined endometrial histology in 635 participants considered to be at increased risk for abnormalities (with unexpected vaginal bleeding or endometrial thickness more than 4 mm).
  
  
  RESULTS
  During the first year of study, mean endometrial thickness increased 1 mm in women receiving tibolone (P<.001), but no further increases were noted during the next 2 years. Diagnostic biopsies among 499 women receiving tibolone and 136 who were receiving placebo showed cumulative incidences of endometrial hyperplasia less than 1%. Among the 15% of women whose biopsy showed an endometrial polyp (similar rate in tibolone and placebo), those receiving tibolone were more than twice as likely to show hyperplasia within the polyp. A marginal increase in grade 1 endometrioid adenocarcinoma (P=.06 compared with placebo) was found among women receiving tibolone. Prevalences of vaginal bleeding during the study were 10.8% in the tibolone group and 2.8% in the placebo group (P<.001).
  
  
  CONCLUSIONS
  Tibolone treatment during 3 years minimally increased endometrial thickness, hyperplastic polyps, endometrial carcinoma, and vaginal bleeding.
authors.affiliation: University of California, San Francisco, San Francisco, California, USA. doc.ettinger@gmail.com
authors.forename: Bruce
authors.initials: B
authors.lastname: Ettinger
authors.forename: Peter
authors.initials: P
authors.lastname: Kenemans
authors.forename: Susan R
authors.initials: SR
authors.lastname: Johnson
authors.forename: Mirjam
authors.initials: M
authors.lastname: Mol-Arts
authors.forename: Steve
authors.initials: S
authors.lastname: Van Os
authors.forename: Wilfried
authors.initials: W
authors.lastname: Seifert
authors.forename: Pierre J M
authors.initials: PJ
authors.lastname: Verweij
authors.forename: Steven R
authors.initials: SR
authors.lastname: Cummings