CK19 and PDX-1 Immunohistochemistry: Accuracy on Detecting Pancreatic Tumor and Its Metastases

Abstract

Background
Metastatic adenocarcinoma of unknown origin remains a serious problem in oncology. Pancreatic cancer is often diagnosed when it
has already metastasized. Therefore immunohistochemistry (IHC) examination for detecting metastases of pancreatic origin is very
important IHC marker of Pancreatic duodenal homeobox-1 (PDX-1) has a good accuracy for detecting metastases of pancreatic
origin, however it is not readily available in many centers in Indonesia. Instead, IHC marker that is often being used is CK19. This
marker is not specific, because it is also expressed by gastrointestinal and hepatobilliary tumors. This evidence-based case report
aims to determine the accuracy of CK19 compared with PDX-1 IHC for detecting pancreatic tumor and its metastases.
Methods
Literature searches were conducted on Pubmed/MEDLINE®
, Scopus®
, Cochrane®
databases. Four articles about PDX-1 and 5 articles
about CK19 that are relevant were found. Those articles were critically appraised.
Results
All articles are considered valid, as they fulfilled the important criteria for journal validity. A study of CK19 IHC found that this marker
has 100% sensitivity and 6% specificity for diagnosing liver metastases from well-differentiated pancreatic ductal adenocarcinoma.
Studies of PDX-1 IHC have different results; a study found that 27 out of 67 were PDX-1 positive in metastases of pancreatic
adenocarcinoma origin, while another study found that PDX-1 has 72% sensitivity and 93% specificity for pancreatic neuroendocrine
tumor, with 100% sensitivity and 75% specificity for pancreatic neuroendocrine tumor metastases.
Conclusion
CK19 IHC is highly sensitive for detecting adenocarcinoma metastases of pancreatic origin, thus it can be utilized as a screening test.
However, CK19 IHC specificity for detecting adenocarcinoma metastases of pancreatic origin is low compared to PDX-1 IHC