title: A double-blind placebo-controlled study to evaluate endometrial safety and gynaecological symptoms in women treated for up to 5 years with tamoxifen or placebo - a substudy for IBIS I Breast Cancer Prevention Trial.
abstract: OBJECTIVE
  This prospective study was performed to investigate the effects of 5-year's use of tamoxifen in preventive setting on endometrium and gynaecological symptoms.
  
  
  METHODS
  Altogether 96 women were treated either with tamoxifen (TAM, n=45) or placebo (PLA, n=51) for up to 5 years in a randomised, double-blind IBIS I breast cancer prevention trial, clinically followed-up for an additional year and for the occurrence of malignancies at least 9 years between 2/1995 and 7/2009 in Finland. The gynaecological follow-up with trans-vaginal ultrasound and endometrial biopsies were performed at baseline, at 2.5 and 5 years and at the 6 years follow-up visit.
  
  
  RESULTS
  Women in the TAM group discontinued the treatment significantly more often (44% versus 22%; p=0.017) and earlier (at 15 versus 30 months; p=0.044), than those in the PLA group. In postmenopausal women the median endometrial thickness was significantly increased at five years in the TAM group (median 4.3 versus 2.0mm, p=0.011), but there was no difference between the groups at one year after the treatment. There were also statistically significantly more referrals to hospitals due to gynaecological findings in the TAM group (risk rates (RR) 3.15; 95% confidence intervals (CI) 1.12-10.10), but no differences in hysterectomy rates or other serious adverse event rates were observed.
  
  
  CONCLUSIONS
  The discontinuation rate in the TAM group was high, and the discontinuations also occurred early. Even though there were significantly more non-serious gynaecological events during the TAM treatment, routine gynaecological follow-up cannot be recommended.
authors: Pirkanmaa Cancer Society, Tampere, Finland. tiina.palva@pirkanmaansyopayhdistys.fi
authors: Tiina
authors: T
authors: Palva
authors: Hannu
authors: H
authors: Ranta
authors: Anna-Maija
authors: AM
authors: Koivisto
authors: Liisa
authors: L
authors: Pylkkänen
authors: Jack
authors: J
authors: Cuzick
authors: Kaija
authors: K
authors: Holli
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000517:prevention & control*; D004311:Double-Blind Method; D004717:Endometrium / Q000187:drug effects*; D005260:Female; D005387:Finland; D006801:Humans; D008875:Middle Aged; D010919:Placebos; D020845:Selective Estrogen Receptor Modulators / Q000009:adverse effects*; D013629:Tamoxifen / Q000009:adverse effects*
chemical_list: D010919:Placebos; D020845:Selective Estrogen Receptor Modulators; D013629:Tamoxifen