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

Objective. Identify correlations between lymph node characteristics and extranodal extension (ENE). Study Design. Retrospective chart review. Setting. Tertiary care center. Methods. Patients who underwent neck dissection for oral cavity squamous cell carcinoma from 2004 to 2018 were included, with a starting sample of 496. The primary outcome was ENE in at least 1 lymph node. Additional variables included number of dissected nodes, positive nodes by level, positive lymph node ratio (LNR), and diameter of metastatic deposit and ENE focus. Univariate and multivariate binary logistic regression analyses were performed to determine correlations between included variables and ENE. Results. Of the 496 patients, 233 had nodal metastasis (47.0%). 13,814 nodes were removed, with 714 (5.2%) containing metastasis. Of the positive nodes, 28.0% had ENE, 47.2% did not have ENE, and 24.8% were unknown. The mean ENE diameter was 5.1 mm (SD, 9.9). On univariate logistic regression analysis, ipsilateral neck LNR per 0.1 unit increase (odds ratio [OR] 1.16, 95% confidence interval [CI] 1.02-1.32, P = .02), metastatic deposit size per 1 mm increase (OR 1.06, CI 1.04-1.08, P < .0001), and clinical T- (P = .02) and N-class (P = .0003) significantly correlated with ENE. On multivariate logistic regression analysis, size of metastatic deposit (OR 1.06, CI 1.03-1.08, P < .0001) remained significantly correlated with ENE. Conclusion: Controlling for confounding variables, size of metastatic deposit was an independent predictor of ENE, suggesting that as the metastatic deposit size increases, the odds of extension through the capsule also increases. This may be due to capsule thinning as the deposit grows or could represent the invasive nature of aggressive disease.