title: Long-term effects on the incidence of second primary cancers in a randomized trial of two and five years of adjuvant tamoxifen.
abstract: BACKGROUND
  Tamoxifen is a well established treatment for breast cancer, but its long-term effects on the incidence of secondary cancers are not fully evaluated.
  
  
  METHODS
  We have studied 4128 postmenopausal patients with early stage breast cancer who were alive and free of breast cancer recurrence after two years of tamoxifen, and who were randomized to receive totally two or five years of therapy.
  
  
  RESULTS
  Compared to patients randomized to two years of tamoxifen the incidence of contralateral breast cancer [hazard ratio (HR) 0.73; 95% CI 0.56-0.96] and of lung cancer (HR 0.45; 95% CI 0.27-0.77), especially squamous cell and small cell lung cancer, were reduced in the five-year group, and similar results were seen when restricting the analysis to the 10-year period after treatment stopped. An increased incidence of endometrial cancer was observed in the five-year group, but the excess risk decreased over time.
  
  
  CONCLUSIONS
  Further studies of the effects of tamoxifen on the risk of different histological types of lung cancer are needed.
authors.affiliation: a Regional Cancer Center South East Sweden , Linköping , Sweden.|b Oncology, Department of Clinical and Experimental Medicine, Faculty of Health Sciences , Linköping University , Linköping , Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Rosell
authors.affiliation: b Oncology, Department of Clinical and Experimental Medicine, Faculty of Health Sciences , Linköping University , Linköping , Sweden.
authors.forename: Bo
authors.initials: B
authors.lastname: Nordenskjöld
authors.affiliation: c Department of Oncology , Umeå University Hospital , Umeå , Sweden.
authors.forename: Nils-Olof
authors.initials: NO
authors.lastname: Bengtsson
authors.affiliation: d Department of Oncology , Karolinska University Hospital , Stockholm , Sweden.
authors.forename: Tommy
authors.initials: T
authors.lastname: Fornander
authors.affiliation: d Department of Oncology , Karolinska University Hospital , Stockholm , Sweden.
authors.forename: Thomas
authors.initials: T
authors.lastname: Hatschek
authors.affiliation: e Department of Oncology , Uppsala University Hospital , Uppsala , Sweden.
authors.forename: Henrik
authors.initials: H
authors.lastname: Lindman
authors.affiliation: f Skånes Department of Oncology , Skåne University Hospital , Lund , Sweden.
authors.forename: Per-Olof
authors.initials: PO
authors.lastname: Malmström
authors.affiliation: g Department of Oncology , Sahlgrenska University Hospital , Göteborg , Sweden.
authors.forename: Arne
authors.initials: A
authors.lastname: Wallgren
authors.affiliation: b Oncology, Department of Clinical and Experimental Medicine, Faculty of Health Sciences , Linköping University , Linköping , Sweden.
authors.forename: Olle
authors.initials: O
authors.lastname: Stål
authors.affiliation: h Department of Medical and Health Sciences , Linköping University , Linköping , Sweden.
authors.forename: John
authors.initials: J
authors.lastname: Carstensen
mesh_terms: D000328:Adult; D000368:Aged; D018931:Antineoplastic Agents, Hormonal / Q000008:administration & dosage*; D001943:Breast Neoplasms / Q000188:drug therapy*; D017024:Chemotherapy, Adjuvant / Q000379:methods; D005260:Female; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology / Q000517:prevention & control; D016609:Neoplasms, Second Primary / Q000453:epidemiology / Q000517:prevention & control; D013629:Tamoxifen / Q000008:administration & dosage*; D013995:Time
chemical_list: D018931:Antineoplastic Agents, Hormonal; D013629:Tamoxifen