title: Androgen receptor expression predicts beneficial tamoxifen response in oestrogen receptor-α-negative breast cancer.
abstract: BACKGROUND
  Although the androgen receptor (AR) is frequently expressed in breast cancer, its relevance in the disease is not fully understood. In addition, the relevance of AR in determining tamoxifen treatment efficiency requires evaluation.
  
  
  OBJECTIVE
  To investigate the tamoxifen predictive relevance of the AR protein expression in breast cancer.
  
  
  METHODS
  Patients were randomised to tamoxifen 40 mg daily for 2 or 5 years or to no endocrine treatment. Mean follow-up was 15 years. Hazard ratios were calculated with recurrence-free survival as end point.
  
  
  RESULTS
  In patients with oestrogen receptor (ER)-negative tumours, expression of AR predicted decreased recurrence rate with tamoxifen (hazard ratio (HR)=0.34; 95% confidence interval (CI)=0.14-0.81; P=0.015), whereas the opposite was seen in the AR- group (HR=2.92; 95% CI=1.16-7.31; P=0.022). Interaction test was significant P<0.001. Patients with triple-negative and AR+ tumours benefitted from tamoxifen treatment (HR=0.12; 95% CI=0.014-0.95 P=0.044), whereas patients with AR- tumours had worse outcome when treated with tamoxifen (HR=3.98; 95% CI=1.32-12.03; P=0.014). Interaction test was significant P=0.003. Patients with ER+ tumours showed benefit from tamoxifen treatment regardless of AR expression.
  
  
  CONCLUSIONS
  AR can predict tamoxifen treatment benefit in patients with ER- tumours and triple-negative breast cancer.
authors.affiliation: Division of Clinical sciences, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping S-581 85, Sweden.
authors.forename: Erik
authors.initials: E
authors.lastname: Hilborn
authors.affiliation: Division of Clinical sciences, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping S-581 85, Sweden.
authors.forename: Jelena
authors.initials: J
authors.lastname: Gacic
authors.affiliation: Department of Oncology-Pathology, Karolinska Institute, Stockholm, Sweden.
authors.forename: Tommy
authors.initials: T
authors.lastname: Fornander
authors.affiliation: Division of Clinical sciences, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping S-581 85, Sweden.
authors.forename: Bo
authors.initials: B
authors.lastname: Nordenskjöld
authors.affiliation: Division of Clinical sciences, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping S-581 85, Sweden.|Department of Oncology, Faculty of Health Sciences, Linköping University, Linköping, Sweden.
authors.forename: Olle
authors.initials: O
authors.lastname: Stål
authors.affiliation: Division of Clinical sciences, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping S-581 85, Sweden.
authors.forename: Agneta
authors.initials: A
authors.lastname: Jansson
mesh_terms: D000368:Aged; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D017024:Chemotherapy, Adjuvant; D047628:Estrogen Receptor alpha / Q000378:metabolism*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D060787:Neoplasm Grading; D009364:Neoplasm Recurrence, Local; D011379:Prognosis; D016016:Proportional Hazards Models; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*; D011944:Receptors, Androgen / Q000378:metabolism*; D011980:Receptors, Progesterone / Q000378:metabolism*; D013629:Tamoxifen / Q000627:therapeutic use*; D064726:Triple Negative Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D047368:Tumor Burden
chemical_list: D018931:Antineoplastic Agents, Hormonal; D047628:Estrogen Receptor alpha; D018719:Erb-b2 Receptor Tyrosine Kinases; D011944:Receptors, Androgen; D011980:Receptors, Progesterone; D013629:Tamoxifen; C410798:AR protein, human; C506487:ESR1 protein, human; C508053:ERBB2 protein, human