title: Diagnostic accuracy of cancer antigen 125 for endometriosis: a systematic review and meta-analysis.
abstract: BACKGROUND
  The development of a non-invasive and accurate diagnostic biomarker for endometriosis is urgently needed.
  
  
  OBJECTIVE
  Evaluate the diagnostic accuracy of serum cancer antigen 125 (CA 125) for endometriosis.
  
  
  METHODS
  We searched EMBASE, MEDLINE, and Web of Science from inception to January 2016.
  
  
  METHODS
  Diagnostic accuracy studies of serum CA 125 (index test) for histologically confirmed endometriosis (reference standard) were included.
  
  
  METHODS
  Two authors independently selected trials, extracted study characteristics and data. Methodological quality was assessed using Quality Assessment of Comparative Diagnostic Accuracy Studies (QUADAS-2) checklist.
  
  
  RESULTS
  Twenty-two studies (16 cohort, six case-control), 3626 participants, were identified. Bivariate hierarchical models were used to pool accuracy data of 14 studies (2920 participants) using CA 125 ≥ 30 units/ml. Pooled specificity was 93% (95% CI 89-95%) and sensitivity 52% (95% CI 38-66%). CA 125 was significantly more sensitive for the diagnosis of moderate or severe endometriosis compared with minimal disease (63%, 95% CI 47-77% versus 24%, 95%CI 19-32%, P-value = 0.001).
  
  
  CONCLUSIONS
  CA 125 performs well as a rule-in test facilitating expedited diagnosis and ensuring investigation and treatment can be confidently tailored for the management of endometriosis. Unfortunately, a negative test, CA 125 < 30 units/ml, is unable to rule out endometriosis.
  
  
  CONCLUSIONS
  Blood test CA 125: a rule-in test for the diagnosis of women presenting with symptoms of endometriosis.
authors.affiliation: Women's Health Research Unit, The Blizard Institute, Barts and the London School of Medicine and Dentistry, London, UK. m.hirsch@qmul.ac.uk.
authors.forename: M
authors.initials: M
authors.lastname: Hirsch
authors.affiliation: Balliol College, University of Oxford, Oxford, UK.|Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK.
authors.forename: Jmn
authors.initials: J
authors.lastname: Duffy
authors.affiliation: Women's Health Research Unit, The Blizard Institute, Barts and the London School of Medicine and Dentistry, London, UK.
authors.forename: C J
authors.initials: CJ
authors.lastname: Davis
authors.affiliation: Madrid Cochrane Collaboration Centre, Francisco de Vitoria University, Madrid, Spain.|Clinical Biostatistics Unit, Ramon y Cajal Institute of Research (IRYCIS) and CIBER Epidemiology and Public Health (CIBERESP), Madrid, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Nieves Plana
authors.affiliation: Women's Health Research Unit, The Blizard Institute, Barts and the London School of Medicine and Dentistry, London, UK.
authors.forename: K S
authors.initials: KS
authors.lastname: Khan
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D018394:CA-125 Antigen / Q000097:blood*; D004715:Endometriosis / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008565:Membrane Proteins / Q000097:blood*; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity
chemical_list: D015415:Biomarkers; D018394:CA-125 Antigen; C451759:MUC16 protein, human; D008565:Membrane Proteins
keywords: Biomarkers; cancer antigen 125; endometriosis; non-invasive diagnosis