title: Factors influencing the hormone receptor and HER2 levels in breast cancer: a population-based analysis.
abstract: BACKGROUND
  Breast cancer (BC) is regarded as a heterogeneous disease that is classified into various molecular subtypes using gene expression analysis. The aim of this study was to perform a population-based analysis of the prevalence of molecular BC subtypes in Turkish women, and to determine their association with known prognostic and clinicopathological factors.
  
  
  METHODS
  A total of 1,025 cases with operable BC, who presented within a 2 year period (2006-2007), were evaluated. Estrogen receptor (ER), progesterone receptor (PR), and HER2 expression were determined immunohistochemically.
  
  
  RESULTS
  68.3% of patients were ER-positive, and 71.5% were PR-positive. Among the 28.3% of HER2-positive tumors, the majority (19.2%) stained +++. Almost 50% of the tumors were ER+ PR+ HER2-, which makes this the predominant tumor type. For both triple-negative and positive status, a ratio of approximately 10% was determined. For ER+ PR+ HER2-, tumor histology, tumor stage, and histological grade were found to be correlated. Menopausal status, obesity, tumor histology, histological grade, in-situ component, and lymphovascular invasion were associated with triple-positive tumors. A significant relationship was found between the variables - including histological grade, in-situ component, and involvement of axillary lymph nodes - and triple-negative status.
  
  
  CONCLUSIONS
  A more thorough understanding of the biological background and underlying mechanisms of BC may allow the development of rational targeted approaches and therapies.
authors.affiliation: Institute of Oncology, University of Istanbul, Turkey. faruktas2002@yahoo.com
authors.forename: Faruk
authors.initials: F
authors.lastname: Tas
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000235:genetics*; D001940:Breast / Q000473:pathology; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology*; D018270:Carcinoma, Ductal, Breast / Q000235:genetics* / Q000473:pathology*; D018275:Carcinoma, Lobular / Q000235:genetics* / Q000473:pathology*; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D008207:Lymphatic Metastasis / Q000473:pathology; D008875:Middle Aged; D060787:Neoplasm Grading; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D009376:Neoplasms, Hormone-Dependent / Q000235:genetics* / Q000473:pathology*; D011379:Prognosis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics*; D011960:Receptors, Estrogen / Q000235:genetics*; D011980:Receptors, Progesterone / Q000235:genetics*; D012307:Risk Factors; D014421:Turkey
chemical_list: D014408:Biomarkers, Tumor; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; C508053:ERBB2 protein, human