HYBRID MODEL FOR THE CLASSIFICATION OF CARCINOMA SUBTYPES

A two-tiered classification system that can be integrated with the current algorithm used by pathologists for identification of the site of origin for ‘malignancy with unknown primary’ is presented. In use, morphology, immunohistochemical (IHC) studies, and microarray-based top tier gene expression classifiers first subclassify cytokeratin positive carcinomas into adenocarcinoma, squamous cell carcinoma, neuroendocrine carcinoma and urothelial carcinoma. Subsequently, organ-specific IHC-markers, if available, are used in conjunction with microarray-based second tier gene expression classifiers to assign the primary site of origin to the sample. This new hybrid approach combines IHC with a hierarchy of quantitative gene expression based classifiers into an algorithmic method that can assist pathologists to further refine and support their decision making process.