title: Oestrogen receptor co-activator AIB1 is a marker of tamoxifen benefit in postmenopausal breast cancer.
abstract: BACKGROUND
  The oestrogen receptor (ER) co-activator amplified in breast cancer 1 (AIB1) has been suggested as a treatment predictive and prognostic marker in breast cancer. Studies have however not been unanimous.
  
  
  METHODS
  AIB1 protein expression was analysed by immunohistochemistry on tissue micro-arrays with tumour samples from 910 postmenopausal women randomised to tamoxifen treatment or no adjuvant treatment. Associations between AIB1 expression, clinical outcome in the two arms and other clinicopathological variables were examined.
  
  
  RESULTS
  In patients with ER-positive breast cancer expressing low tumour levels of AIB1 (<75%), we found no significant difference in recurrence-free survival (RFS) or breast cancer-specific survival (BCS) between tamoxifen treated and untreated patients. In patients with high AIB1 expression (>75%), there was a significant decrease in recurrence rate (HR 0.40, 95% CI 0.26-0.61, P < 0.001) and breast cancer mortality rate (HR 0.38, 95% CI 0.21-0.69, P = 0.0015) with tamoxifen treatment. In the untreated arm, we found high expression of AIB1 to be significantly associated with lower RFS (HR 1.74, 95% CI 1.20-2.53, P = 0.0038).
  
  
  CONCLUSIONS
  Our results suggest that high AIB1 is a predictive marker of good response to tamoxifen treatment in postmenopausal women and a prognostic marker of decreased RFS in systemically untreated patients.
authors.affiliation: Division of Oncology, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, County Council of Östergötland, Linköping, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Weiner
authors.forename: L
authors.initials: L
authors.lastname: Skoog
authors.forename: T
authors.initials: T
authors.lastname: Fornander
authors.forename: B
authors.initials: B
authors.lastname: Nordenskjöld
authors.forename: D C
authors.initials: DC
authors.lastname: Sgroi
authors.forename: O
authors.initials: O
authors.lastname: Stål
mesh_terms: D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000401:mortality; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D009364:Neoplasm Recurrence, Local / Q000188:drug therapy; D056921:Nuclear Receptor Coactivator 3 / Q000378:metabolism*; D017698:Postmenopause; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000378:metabolism*; D013629:Tamoxifen / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: D018931:Antineoplastic Agents, Hormonal; D014408:Biomarkers, Tumor; D056921:Nuclear Receptor Coactivator 3; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D013629:Tamoxifen; C538866:NCOA3 protein, human; C508053:ERBB2 protein, human
keywords: AIB1; HER2; SRC-3; breast cancer; prognosis; treatment prediction