The median correlation coefficients between sRNA-qPCR and FFPE-qPCR was even worse (< 0.3), presumably caused by differences in the tumor microenvironment (immune, stromal, or endothelial cells and/or exosomal sRNAs): For sRNA-seq and sRNA-qPCR EpCAM positive tumor cells were enriched removing components of the microenvironment and exosomes, whereas macro-dissected FFPE tissues were not enriched for tumor cells. The gene discussed is EPCAM; the disease is neoplasm.