KRT19 and head and neck squamous cell carcinoma: An immunobead RT-PCR method, combining immunomagnetic enrichment of tumor epithelial cells with RT-PCR analysis of ESX, EGFR, EphB4 and CK19 was optimised using reconstruction experiments with two HNSCC cell lines, then used to detect CTCs in the peripheral blood from 16 patients with advanced HNSCC.