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Validating a fully automated real-time PCR-based system for use in the molecular diagnostic analysis of colorectal carcinoma: a comparison with NGS and IHC
  1. Richard Colling1,2,3,
  2. Lai Mun Wang1,4,5,
  3. Elizabeth Soilleux1,6
  1. 1Department of Cellular Pathology, Oxford University Hospitals NHS Trust, John Radcliffe Hospital, Oxford, UK
  2. 2Oxford Molecular Diagnostics Centre, Molecular Haematology, Oxford University Hospitals NHS Trust, John Radcliffe Hospital, Oxford, UK
  3. 3Department of Oncology, University of Oxford, John Radcliffe Hospital, Oxford, UK
  4. 4Department of Laboratory Medicine, Changi General Hospital, Singapore, Singapore
  5. 5Ludwig Institute for Cancer Research, University of Oxford, Old Road Campus Research Building, Oxford, UK
  6. 6Nuffield Division of Clinical Laboratory Sciences, University of Oxford, John Radcliffe Hospital, Oxford, UK
  1. Correspondence to Dr Richard Colling, Department of Cellular Pathology, Level 1, John Radcliffe Hospital, Headley Way, Headington, Oxford OX3 9DU, UK; rtcolling{at}


Background Molecular testing is increasingly needed in colorectal carcinoma (CRC) and the current clinically relevant mutations are in BRAF, KRAS and NRAS. This study aimed to further validate a new alternative polymerase chain reaction (PCR) platform (Idylla, Biocartis) against existing next-generation sequencing (NGS) and immunohistochemistry (IHC) assays.

Methods 56 Idylla tests were performed on 43 CRC cases, in a total of 74 comparisons against an NGS panel (Ion Torrent) and the VE1 (anti-BRAF) antibody IHC. Discrepant cases were also compared with either conventional (Cobas) or droplet digital PCR (Bio-Rad).

Results Idylla showed an overall concordance of 100% (95% CI 93% to 100%) with comparator molecular testing and indications were that Idylla is likely to be more sensitive than routine NGS. BRAF IHC showed 90% concordance with NGS (95% CI 70% to 97%).

Conclusions This study validates Idylla in formalin-fixed, paraffin-embedded CRC tissue. BRAF IHC, however, is an unreliable substitute for molecular testing in CRC.


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  • Handling editor Runjan Chetty

  • Contributors RC devised the project and carried out the Idylla testing. All authors contributed to the final manuscript.

  • Funding Consumables, tissue handling costs and additional test cartridges were funded by the Oxfordshire Health Services Research Committee (Fund 8262 to RC/ES).

  • Competing interests None declared.

  • Ethics approval The National Research and Ethics Service (Oxfordshire Research and Ethics Committee A; reference 04/Q1604/21).

  • Provenance and peer review Not commissioned; externally peer reviewed.