Validation of a microRNA-based qRT-PCR test for accurate identification of tumor tissue origin

Shai Rosenwald, Shlomit Gilad, Sima Benjamin, Danit Lebanony, Nir Dromi, Alexander Faerman, Hila Benjamin, Ronen Tamir, Meital Ezagouri, Eran Goren, Iris Barshack, Dvora Nass, Ana Tobar, Meora Feinmesser, Nitzan Rosenfeld, Ilit Leizerman, Karin Ashkenazi, Yael Spector, Ayelet Chajut*, Ranit Aharonov

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

116 Scopus citations


Identification of the tissue of origin of a tumor is vital to its management. Previous studies showed tissue-specific expression patterns of microRNA and suggested that microRNA profiling would be useful in addressing this diagnostic challenge. MicroRNAs are well preserved in formalin-fixed, paraffin-embedded (FFPE) samples, further supporting this approach. To develop a standardized assay for identification of the tissue origin of FFPE tumor samples, we used microarray data from 504 tumor samples to select a shortlist of 104 microRNA biomarker candidates. These 104 microRNAs were profiled by proprietary quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) on 356 FFPE tumor samples. A total of 48 microRNAs were chosen from this list of candidates and used to train a classifier. We developed a clinical test for the identification of the tumor tissue of origin based on a standardized protocol and defined the classification criteria. The test measures expression levels of 48 microRNAs by qRT-PCR, and predicts the tissue of origin among 25 possible classes, corresponding to 17 distinct tissues and organs. The biologically motivated classifier combines the predictions generated by a binary decision tree and K-nearest neighbors (KNN). The classifier was validated on an independent, blinded set of 204 FFPE tumor samples, including nearly 100 metastatic tumor samples. The test predictions correctly identified the reference diagnosis in 85% of the cases. In 66% of the cases the two algorithm predictions (tree and KNN) agreed on a single-tissue origin, which was identical to the reference diagnosis in 90% of cases. Thus, a qRT-PCR test based on the expression profile of 48 tissue-specific microRNAs allows accurate identification of the tumor tissue of origin.

Original languageEnglish
Pages (from-to)814-823
Number of pages10
JournalModern Pathology
Issue number6
StatePublished - Jun 2010


  • CUP
  • Diagnostics
  • MicroRNA
  • Tumor of origin


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