Cytokeratin 19 expression in early oral squamous cell carcinoma and their metastasis : Inadequate biomarker for one-step nucleic acid amplification implementation in sentinel lymph node biopsy procedure

BACKGROUND: Intraoperative analysis of lymph nodes during a sentinel lymph node biopsy (SLNB) procedure could result in one-step surgery for early oral squamous cell carcinoma (OSCC) with an occult nodal metastasis. One-step nucleic acid amplification rapidly detects cytokeratin 19 (CK19) RNA with high accuracy. Sensitivity and specificity of CK19 expression in OSCC was evaluated. METHODS: Immunohistochemical CK19 expression was done in 207 patients with OSCC with 65 cases of paired nodal metastases. RESULTS: CK19 was expressed in 65% of all OSCC and even less in early OSCC (56%), with poor correlation between primary tumor and (occult) nodal metastasis. Furthermore, ectopic glandular tissue in close proximity of lymph nodes showed strong CK19 expression. CONCLUSION: CK19 lacks both sensitivity and specificity as a biomarker for nodal metastasis in OSCC, which questions the suitability for CK19-based one-step nucleic acid amplification in SLNB procedures. Therefore, future studies should focus on other biomarkers, because the concept of fast intraoperative diagnostics during SLNB remains attractive