KRT19 and colorectal carcinoma: We therefore decided to design a method based on a real-time Taqman PCR reverse–transcriptase polymerase chain reaction (real-time RT–PCR) assay to detect cytokeratin 19 (CK19) mRNA marker of occult tumour cells in lymph nodes of patients undergoing neck dissection for HNSCC as such a marker has been shown to detect accurately micrometastases in patients with lung, oesophageal, gastric, breast or colorectal carcinoma (Izbicki et al, 1997; Czerniecki et al, 1999; Weitz et al, 1999; Gai et al, 2000; Saintigny et al, 2005).