title: Carcinoembryonic antigen is the preferred biomarker for in vivo colorectal cancer targeting.
abstract: BACKGROUND
  Colorectal cancer-specific biomarkers have been used as molecular targets for fluorescent intra-operative imaging, targeted PET/MRI, and selective cytotoxic drug delivery yet the selection of biomarkers used is rarely evidence-based. We evaluated sensitivities and specificites of four of the most commonly used markers: carcinoembryonic antigen (CEA), tumour-associated glycoprotein-72 (TAG-72), folate receptor-α (FRα) and Epithelial growth factor receptor (EGFR).
  
  
  METHODS
  Marker expression was evaluated semi-quantitatively in matched mucosal and colorectal cancer tissues from 280 patients using immunohistochemistry (scores of 0-15). Matched positive and negative lymph nodes from 18 patients were also examined.
  
  
  RESULTS
  Markers were more highly expressed in tumour tissue than in matched normal tissue in 98.8%, 79.0%, 37.1% and 32.8% of cases for CEA, TAG-72, FRα and EGFR, respectively. Carcinoembryonic antigen showed the greatest differential expression, with tumours scoring a mean of 10.8 points higher than normal tissues (95% CI 10.31-11.21, P<0.001). Similarly, CEA showed the greatest differential expression between positive and negative lymph nodes. Receiver operating characteristic analyses showed CEA to have the best sensitivity (93.7%) and specificity (96.1%) for colorectal cancer detection.
  
  
  CONCLUSIONS
  Carcinoembryonic antigen has the greatest potential to allow highly specific tumour imaging and drug delivery; future translational research should aim to exploit this.
authors: Leeds Institute of Molecular Medicine, Wellcome Trust Brenner Building, St. James's University Hospital, University of Leeds, Leeds LS9 7TF, UK. jimtiernan1@gmail.com
authors: J P
authors: JP
authors: Tiernan
authors: S L
authors: SL
authors: Perry
authors: E T
authors: ET
authors: Verghese
authors: N P
authors: NP
authors: West
authors: S
authors: S
authors: Yeluri
authors: D G
authors: DG
authors: Jayne
authors: T A
authors: TA
authors: Hughes
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000951:Antigens, Neoplasm / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000378:metabolism*; D002272:Carcinoembryonic Antigen / Q000378:metabolism*; D016022:Case-Control Studies; D003106:Colon / Q000378:metabolism*; D015179:Colorectal Neoplasms / Q000378:metabolism* / Q000473:pathology; D066246:ErbB Receptors / Q000378:metabolism; D005260:Female; D058975:Folate Receptor 1 / Q000378:metabolism; D005500:Follow-Up Studies; D006023:Glycoproteins / Q000378:metabolism; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D011446:Prospective Studies; D012372:ROC Curve; D012007:Rectum / Q000378:metabolism*
chemical_list: D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D002272:Carcinoembryonic Antigen; D058975:Folate Receptor 1; D006023:Glycoproteins; C047052:tumor-associated antigen 72; C512478:EGFR protein, human; D066246:ErbB Receptors