title: A systematic review to establish the frequency of cyclooxygenase-2 expression in normal breast epithelium, ductal carcinoma in situ, microinvasive carcinoma of the breast and invasive breast cancer.
abstract: BACKGROUND
  Epidemiological studies have suggested a protective effect of cyclooxygenase (COX)-inhibiting non-steroidal anti-inflammatory drugs in breast cancer risk and disease progression. We performed a systematic review to evaluate the frequency of COX-2 expression in normal breast epithelium, ductal carcinoma in situ of breast (DCIS), DCIS-adjoining invasive breast cancer, microinvasive carcinoma of the breast (MICB) and invasive breast cancer.
  
  
  METHODS
  Literature searches were carried out on MEDLINE, EMBASE and Web of Science from their commencement until September 2010. Primary studies examining COX-2 expression by immunohistochemistry methodology were included. Meta-analyses were carried out using random effects models for individual study estimates of COX-2 expression and pooled to give an overall estimate.
  
  
  RESULTS
  The pooled prevalences (95% confidence intervals) of COX-2 expressions were 53% (44-61) in DCIS studies and 42% (36-49) in the invasive breast cancer studies. There were too few studies involving normal breast epithelium, DCIS-adjoining invasive breast cancer and MICB to conduct meta-analyses.
  
  
  CONCLUSIONS
  The findings from our meta-analyses have shown similar COX-2 expression in DCIS and invasive breast cancer. This may suggest the involvement of COX-2 in early carcinogenesis. Further studies of COX-2 expression in DCIS are required to investigate the use of COX-2 as a potential drug target for prevention of disease progression in DCIS.
authors.affiliation: Centre for Health Improvement, Queen's University, School of Medicine, Dentistry and Biomedical Sciences, Institute of Clinical Science Building, Block B, Royal Victoria Hospital, Grosvenor Road, Belfast BT12 6BA, UK. jglover02@qub.ac.uk
authors.forename: J A
authors.initials: JA
authors.lastname: Glover
authors.forename: C M
authors.initials: CM
authors.lastname: Hughes
authors.forename: M M
authors.initials: MM
authors.lastname: Cantwell
authors.forename: L J
authors.initials: LJ
authors.lastname: Murray
mesh_terms: D014408:Biomarkers, Tumor / Q000378:metabolism*; D001940:Breast / Q000378:metabolism* / Q000473:pathology; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D018270:Carcinoma, Ductal, Breast / Q000378:metabolism* / Q000473:pathology; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000378:metabolism* / Q000473:pathology; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D005260:Female; D006801:Humans; D015201:Meta-Analysis as Topic; D009361:Neoplasm Invasiveness
chemical_list: D014408:Biomarkers, Tumor; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human