Focus : Carcinoembryonic antigen is the preferred biomarker for in vivo colorectal cancer targeting

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 endothelial 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.Conclusion:Carcinoembryonic antigen has the greatest potential to allow highly specific tumour imaging and drug delivery; future translational research should aim to exploit this.

Source: Carcinoembryonic antigen is the preferred biomarker for in vivo colorectal cancer targeting. Tiernan JP, Perry SL, Verghese ET, West NP, Yeluri S, Jayne DG, Hughes TA. Br J Cancer. 2013 Jan 15.

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http://www.nature.com/bjc/journal/vaop/ncurrent/pdf/bjc2012605a.pdf