Correlation of Lymph Node Characteristics and Extranodal Extension in Oral Cavity Squamous Cell Carcinoma

Introduction: Extranodal extension (ENE) is a marker of aggressive disease and is associated with poor prognosis in oral cavity squamous cell carcinoma (OCSCC). A more in-depth understanding of relationships between lymph node characteristics and ENE could help predict ENE prior to surgery and inform treatment plans. Currently published literature evaluating these relationships are either dated, have a limited sample size, or focus broadly on head and neck cancer rather than OCSCC.

Methods: A retrospective chart review was conducted at a tertiary care center using tumor registry and pathology data. Adult patients who underwent neck dissection for OCSCC from 2004-2018 were included, with a final sample of 498. The primary outcome was presence of ENE in at least one lymph node. Additional lymph node variables included size of metastatic deposit, size of ENE focus, total number of dissected nodes, number of positive nodes by neck level, and positive lymph node ratio (LNR). Univariate and multivariate binary logistic regression analyses were performed to identify correlations between included variables and ENE.

Results: A total of 13,875 nodes were removed, of which 712 (5.1%) were positive for metastasis. Of the positive nodes, 28.1% had ENE, 47.0% did not have ENE, and 24.8% were unknown. The mean (SD) size of ENE was 5.1 mm (9.9). On univariate and multivariate logistic regression analyses, LNR in the ipsilateral neck per 0.1 unit increase (OR 1.2, CI 1.02-1.30, p=0.03; OR 1.2, CI 1.02-1.4, p=0.03) and size of metastatic deposit per 1 mm increase (OR 1.06, CI 1.03-1.08, p< 0.0001; OR 1.05, CI 1.03-1.07, p< 0.0001) were significantly correlated with presence of ENE in metastatic nodes.

Conclusions: This study offers insight into important clinicopathologic details of lymph node metastases in OCSCC. Controlling for potential confounding variables, LNR in the ipsilateral neck and size of metastatic deposit were independent predictors of ENE. This information may be beneficial for adjuvant treatment planning and could play a role in counseling patients as to the likelihood of recommending concurrent chemoradiation after surgery.