A multi-institutional group has validated a predefined 1,550-gene expression profile for identifying tumor tissue of origin. Malignancies found in unexpected locations, or with poorly differentiated morphologies, can pose a challenge for tissue of origin determination.
Current histologic and imaging techniques fail to yield definitive identification, according to lead author Federico A. Monzon, MD and colleagues.
The group evaluated 547 frozen specimens representing 15 tissues of origin with the Pathwork Tissue of Origin Test, in which microarray technology measures gene expression pattern.
According to the study results, the test had an overall sensitivity of 87.8% and overall specificity of 99.4%. Performance within the subgroup of metastatic tumors (n = 258) was found to be slightly lower than that of the poorly differentiated and undifferentiated primary tumor subgroup, 84.5% and 90.7%, respectively (J Clin Oncol online, March 30, 2009).