title: Null association between tamoxifen use and dementia in Danish breast cancer patients.
abstract: BACKGROUND
  Concerns have been raised about the risk of dementia associated with antiestrogen adjuvant therapy in breast cancer, but study results have been inconsistent. We examined whether tamoxifen or other endocrine therapy was associated with dementia risk in a large population of patients with breast cancer.
  
  
  METHODS
  We used Danish nationwide medical registries to identify patients with breast cancer diagnosed between 1990 and 2004, use of endocrine therapy, and subsequent diagnoses of dementia. We used Cox regression to estimate the risk of dementia among patients who received five years of tamoxifen or other endocrine therapies.
  
  
  RESULTS
  The study included 16,419 patients with breast cancer. In this cohort, 37% were unexposed to endocrine therapy, 9% had five years of tamoxifen therapy, and 54% had other endocrine regimens, some of them containing tamoxifen for less than five years with subsequent aromatase inhibitor therapy. Tamoxifen therapy was associated with a near-null risk of dementia [HR, 1.4; 95% confidence interval (CI), 1.0-1.9], and a null association was observed after death was taken into account as a competing risk (sub-HR, 1.0; 95% CI, 0.76-1.4).
  
  
  CONCLUSIONS
  No clinically relevant association between use of tamoxifen or other endocrine therapy and risk of dementia was observed.
  
  
  CONCLUSIONS
  Our result contradicts earlier research findings suggesting tamoxifen and other endocrine therapies increase the risk of dementia in breast cancer patients.
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Olof Palmes Allé 43-45, 8200 Aarhus N, Denmark. ao@dce.au.dk
authors.forename: Anne Gulbech
authors.initials: AG
authors.lastname: Ording
authors.forename: Anders Bonde
authors.initials: AB
authors.lastname: Jensen
authors.forename: Deirdre
authors.initials: D
authors.lastname: Cronin-Fenton
authors.forename: Lars
authors.initials: L
authors.lastname: Pedersen
authors.forename: Henrik Toft
authors.initials: HT
authors.lastname: Sørensen
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Lash
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000188:drug therapy*; D003704:Dementia / Q000139:chemically induced / Q000453:epidemiology*; D004965:Estrogen Antagonists / Q000008:administration & dosage* / Q000009:adverse effects; D005260:Female; D006801:Humans; D008875:Middle Aged; D016017:Odds Ratio; D013548:Sweden / Q000453:epidemiology; D013629:Tamoxifen / Q000008:administration & dosage* / Q000009:adverse effects
chemical_list: D004965:Estrogen Antagonists; D013629:Tamoxifen