EPCAM and head and neck squamous cell carcinoma: Since EpCAM expression was shown to be downregulated in squamous cell carcinomas [10], whereas EGFR is frequently overexpressed in HNSCC [11], we hypothesized that the inclusion of both tumor–associated markers may increase sensitivity for the detection of CTCs, especially in tumors with an EMT phenotype displaying low or absent EpCAM expression.