Keratin mRNA for detecting micrometastasis in cervical lymph nodes of oral cancer

We studied three keratin (K) gene candidates, K13, K19, and K20 mRNAs, for detecting micrometastases in cervical lymph nodes (LNs) by reverse transcriptase-polymerase chain reaction (RT-PCR). Of 166 histologically metastasis-negative nodes, 24 micrometastatic LNs (14.4%) were detected based on K13 gene expression. Keratin 19 mRNA is an inadequate marker for the genetic diagnosis due to not only illegitimate gene expression from lymphatic tissue but also gene expression from the ectopic salivary gland. Keratin 20 mRNA showed low sensitivity. It is suggested that K13 mRNA may be a promising tumor marker among these keratin genes for detecting the micrometastases in cervical LNs of oral cancer.