Why We Need Correct ICD Coding for CCA

June/July 2022, Vol 3, No 2

Based on their anatomic site of origin, cholangiocarcinomas (CCAs) are classified as intrahepatic (iCCA), perihilar (pCCA), or distal (dCCA).1 Each has unique epidemiology, pathobiology, and clinical presentation; thus each requires a unique management approach. At the 2022 Cholangiocarcinoma Foundation annual meeting, Dr Shahid Khan, Clinical Senior Lecturer at Imperial College London, discussed the need for correct International Classification of Diseases (ICD) coding for CCA.

It is widely reported that iCCA rates are on the rise while extrahepatic CCA (eCCA) rates are decreasing.2 However, it is unclear whether this reported increase in iCCA rates represents a true clinical trend or is the result of inaccurate coding systems currently used to record CCA data.

Indeed, Selvadurai and colleagues found that CCA miscoding was common in hepatobiliary centers in the United Kingdom.3 In their retrospective study, diagnosis of CCA based on clinical case notes examined by 2 independent investigators was compared with the originally allocated ICD-10 codes (2015-2017) at 3 independent UK regional hepatobiliary and pancreatic centers. Of the 625 CCA cases reviewed, 226 were originally coded as iCCA; however, the majority of these (57%) were coded incorrectly. Of all CCA cases, 92% were incorrectly coded as iCCA.

Two ICD coding systems are used in clinical practice. ICD-10 is a topographic code published by the World Health Organization for all cancer and noncancer diagnoses. ICD-O, published by the International Agency for Research on Cancer, is specific for cancer and uses both topographic and morphologic codes to describe tumors.

ICD coding systems may cause inaccurate recording of CCA data for many reasons:

  • ICD-10 and ICD-11 have separate codes for iCCA and eCCA but not for pCCA/dCCA.
  • ICD-O has a morphology code for pCCA but inconsistently cross-references this code to iCCA or eCCA.
  • ICD-O changes every few years, and countries adopt new versions at different times.

Key takeaways:

  • International consistency and accuracy in topographic classification of CCA is needed to enable accurate monitoring of disease rates.
  • CCA/biliary tract cancer trends must be interpreted with caution.
  • Data must be recorded uniformly and accurately; responsibility to do so lies with both clinicians and cancer registries.
  • ICD-11 and subsequent iterations of ICD-O should have separate topography and morphology codes for iCCA, pCCA, and dCCA.

Dr Khan concluded: “However cholangiocarcinoma is classified, its overall incidence and therefore mortality are rising. Urgent studies into its causes, more effective therapies, and better ways to diagnose it are needed.”


  1. Banales JM, Marin JJG, Lamarca A, et al. Cholangiocarcinoma 2020: the next horizon in mechanisms and management. Nat Rev Gastroenterol Hepatol. 2020;17:557-588.
  2. Khan SA, Tavolari S, Brandi G. Cholangiocarcinoma: epidemiology and risk factors. Liver Int. 2019;39(suppl_1):19-31.
  3. Selvadurai S, Mann K, Mithra S, Bridgewater J, Malik H, Khan SA. Cholangiocarcinoma miscoding in hepatobiliary centres. Eur J Surg Oncol. 2021;47(3 Pt B):635-639.

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