Tissue of Origin Test
The science behind the test: The Tissue of Origin Test, offered by the Pathwork Diagnostics Laboratory Service, is supported by extensive analytical and clinical validation data from robust, multi-center clinical studies. The results of these studies are meaningful because they highlight not only the accuracy of the results, but also their consistency from one laboratory setting to another.
A large-scale validation study was published in the January 2011 Journal of Molecular Diagnostics. The study comprised 462 metastatic, poorly differentiated, or undifferentiated tumor specimens that had been diagnosed using current methodologies:5
The test demonstrated 89% positive percent agreement (akin to sensitivity) with available diagnoses and 99% negative percent agreement (akin to specificity) using formalin-fixed, paraffin-embedded (FFPE) tumor specimens, the most common clinical specimen type.
In an independent validation study by the University of California, San Francisco published in Clinica Chimica Acta, 37 FFPE clinical specimens were tested using the Tissue of Origin Test. In 95% of the cases, the test results were in agreement with the reference diagnosis.6
In a reproducibility analysis, the Tissue of Origin Test demonstrated an average 89% overall concordance across three laboratories in a cross-laboratory comparison study of 149 metastatic and poorly differentiated and undifferentiated tissue specimens.5
A recent study of 111 cases derived from 66 academic and community practices showed that after receiving the Tissue of Origin Test results for patients with difficult-to-diagnose primary cancers, the oncologist’s determination of the primary diagnosis was changed in the majority of patients and cancer-specific management changed for two-thirds of the patients. A majority of the oncologists identified the Tissue of Origin Test results as influencing the decision to make a change in therapy.7
A study published in the peer-reviewed journal Cancer Cytopathology demonstrated the capability of the Tissue of Origin Test to be performed on a variety of body fluid cytology specimens preserved in FFPE. The test successfully yielded results in 89% of the specimens examined and correctly identified the available diagnosis with a 94.1% agreement.8
