Intraoperative Sentinel Lymph Node Evaluation:Implications of Cytokeratin 19 Expression for the Adoption of OSNA in Oral Squamous Cell Carcinoma

BACKGROUND: Intraoperative analysis of sentinel lymph nodes would enhance the care of early-stage oral squamous cell carcinoma (OSCC). We determined the frequency and extent of cytokeratin 19 (CK19) expression in OSCC primary tumours and surrounding tissues to explore the feasibility of a “clinic-ready” intraoperative diagnostic test (one step nucleic acid amplification—OSNA, sysmex). METHODS: Two cohorts were assembled: cohort 1, OSCC with stage and site that closely match cases suitable for sentinel lymph node biopsy (SLNB); cohort 2, HNSCC with sufficient fresh tumour tissue available for the OSNA assay (>50 mg). CK19 assays included qRT-PCR, RNA in situ hybridisation (ISH), and immunohistochemistry (IHC), as well as OSNA. RESULTS: CK19 mRNA expression was detected with variable sensitivity, depending on method, in 60–80% of primary OSCC tumours, while protein expression was observed in only 50% of tumours. Discordance between different techniques indicated that OSNA was more sensitive than qRT-PCR or RNA-ISH, which in turn were more sensitive than IHC. OSNA results showed CK19 expression in 80% of primary cases, so if used for diagnosis of lymph node metastasis would lead to a false-negative result in 20% of patients with cervical lymph node metastases. CONCLUSIONS: OSNA in its current form is not suitable for use in OSCC SLNB due to inadequate expression of the CK19 target in all case. However, the same assay technology would likely be very promising if applied using a more ubiquitous squamous epithelial target. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1245/s10434-016-5337-6) contains supplementary material, which is available to authorized users

The relevance of surgical margins in clinically early oral squamous cell carcinoma.

OBJECTIVES:There is controversy regarding surgical margins in the management of early oral squamous cell carcinoma (OSCC). The main objectives of this study were to assess the: relevance of the margin independent of tumour variables; threshold for a safe margin; relevance of dysplasia at the margin. MATERIALS & METHODS:UK based retrospective multicenter cohort study of patients with previously untreated and clinically early OSCC between 1998 and 2016. All patients had surgery as the primary modality and had surgical staging of the neck. Minimum follow-up was 2 years. Margins were classified as: clear ≥5.0 mm; close 1.0-4.9 mm; involved not cut-through (INC-T) 0.1-0.9 mm; cut-through (C-T) 0 mm. RESULTS:669 patients were included. After adjusting for tumour variables Cox multivariate regression analysis demonstrated that close margins had similar survival outcomes to clear margins (Hazard Ratio(HR) 0.99 (95%CI 0.50-1.95) for Local Recurrence Free Survival (LRFS); HR 1.08 (95%CI 0.7-1.66) for Disease Free Survival (DFS); HR 0.74 (95%CI 0.44-1.25) for Disease Specific Survival (DSS); HR 0.80 (95%CI 0.58-1.11) for Overall Survival (OS)). C-T margins had significantly worse LRFS (HR 5.01 (95%CI 2.02-12.39)) and DFS (HR 2.58 (95%CI 1.28-5.20)). INC-T margins had significantly worse DFS (HR 1.98 (95% CI 1.01-3.87)). Time dependent receiver operating characteristic curve analysis did not demonstrate a clear margin threshold for LRFS within 24 months (AUC = 0.53 (95%CI 0.41-0.64)). Dysplasia at the margin did not influence LRFS or DFS. CONCLUSION:Only resection margins <1 mm independently affected survival outcomes. This should be considered when making decisions regarding adjuvant treatment