title: Long-term endometrial effects in postmenopausal women with early breast cancer participating in the Intergroup Exemestane Study (IES)--a randomised controlled trial of exemestane versus continued tamoxifen after 2-3 years tamoxifen.
abstract: BACKGROUND
  The antiestrogen tamoxifen may have partial estrogen-like effects on the postmenopausal uterus. Aromatase inhibitors (AIs) are increasingly used after initial tamoxifen in the adjuvant treatment of postmenopausal early breast cancer due to their mechanism of action: a potential benefit being a reduction of uterine abnormalities caused by tamoxifen.
  
  
  METHODS
  Sonographic uterine effects of the steroidal AI exemestane were studied in 219 women participating in the Intergroup Exemestane Study: a large trial in postmenopausal women with estrogen receptor-positive (or unknown) early breast cancer, disease free after 2-3 years of tamoxifen, randomly assigned to continue tamoxifen or switch to exemestane to complete 5 years adjuvant treatment. The primary end point was the proportion of patients with abnormal (> or =5 mm) endometrial thickness (ET) on transvaginal ultrasound 24 months after randomisation.
  
  
  RESULTS
  The analysis included 183 patients. Two years after randomisation, the proportion of patients with abnormal ET was significantly lower in the exemestane compared with tamoxifen arm (36% versus 62%, respectively; P = 0.004). This difference emerged within 6 months of switching treatment (43.5% versus 65.2%, respectively; P = 0.01) and disappeared within 12 months of treatment completion (30.8% versus 34.7%, respectively; P = 0.67).
  
  
  CONCLUSIONS
  Switching from tamoxifen to exemestane significantly reverses endometrial thickening associated with continued tamoxifen.
authors.affiliation: Department of Oncology, Singleton Hospital, South West Wales Cancer Institute, Swansea. Electronic address: gianfilippo.bertelli@swansea-tr.wales.nhs.uk.
authors.forename: G
authors.initials: G
authors.lastname: Bertelli
authors.affiliation: ICR-CTSU, Section of Clinical Trials, Institute of Cancer Research, Sutton, UK.
authors.forename: E
authors.initials: E
authors.lastname: Hall
authors.affiliation: ICR-CTSU, Section of Clinical Trials, Institute of Cancer Research, Sutton, UK.
authors.forename: E
authors.initials: E
authors.lastname: Ireland
authors.affiliation: ICR-CTSU, Section of Clinical Trials, Institute of Cancer Research, Sutton, UK.
authors.forename: C F
authors.initials: CF
authors.lastname: Snowdon
authors.affiliation: Department of Oncology and Radiotherapy, Medical University of Gdańsk, Gdańsk, Poland.
authors.forename: J
authors.initials: J
authors.lastname: Jassem
authors.affiliation: Department of Oncology, Regional Cancer Center, Opole, USA.
authors.forename: K
authors.initials: K
authors.lastname: Drosik
authors.affiliation: Department of Chemotherapy, Maritime Hospital, Gdynia, Poland.
authors.forename: H
authors.initials: H
authors.lastname: Karnicka-Mlodkowska
authors.affiliation: Cancer Research UK Department of Cancer Medicine, Imperial College London, Hammersmith Hospitals Trust, London, UK.
authors.forename: R C
authors.initials: RC
authors.lastname: Coombes
authors.affiliation: ICR-CTSU, Section of Clinical Trials, Institute of Cancer Research, Sutton, UK.
authors.forename: J M
authors.initials: JM
authors.lastname: Bliss
mesh_terms: D000368:Aged; D000730:Androstadienes / Q000627:therapeutic use*; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use*; D047072:Aromatase Inhibitors / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology; D018270:Carcinoma, Ductal, Breast / Q000188:drug therapy / Q000473:pathology; D018275:Carcinoma, Lobular / Q000188:drug therapy / Q000473:pathology; D004311:Double-Blind Method; D016889:Endometrial Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000473:pathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007390:International Agencies; D008875:Middle Aged; D017698:Postmenopause; D015996:Survival Rate; D013629:Tamoxifen / Q000627:therapeutic use*; D013997:Time Factors; D016896:Treatment Outcome; D014463:Ultrasonography
chemical_list: D000730:Androstadienes; D018931:Antineoplastic Agents, Hormonal; D047072:Aromatase Inhibitors; D013629:Tamoxifen; C056516:exemestane