The impact of microscopic versus macroscopic extranodal extension in oral cavity squamous cell carcinoma: National cancer database analysis and review of the literature

Objective: To analyze the prognostic significance of microscopic vs macroscopic extranodal extension and to assess the impact of chemoradiation on overall survival among patients with oral cavity squamous cell carcinoma and varying degrees of extranodal extension. Methods: Utilizing the National Cancer Database, we performed a retrospective cohort study of 7975 patients with oral cavity squamous cell carcinoma and varying degrees of extranodal extension who underwent primary surgical intervention. Propensity-score matched models following Cox regression analyses allowed us to assess the impact of adjuvant radiation alone vs adjuvant chemoradiation on overall survival in patients with microscopic extranodal extension and macroscopic extranodal extension. Results: 7975 patients with oral cavity squamous cell carcinoma were included in the final analysis. Within this cohort, 25.4% had microscopic extranodal extension and 5.2% had macroscopic extranodal extension. On univariate analysis, we found that microscopic and macroscopic extranodal extension were associated with decreased overall survival when compared to those with positive nodes without extranodal extension (HR = 1.67; 95% CI 1.56, 1.79 and HR = 1.88; 95% CI 1.66, 2.14, respectively). On multivariate analysis after propensity-score matching, we found no significant difference in overall survival in patients who received adjuvant radiation alone vs. adjuvant chemoradiation for both microscopic and macroscopic extranodal extension. Conclusion: Our data suggest that microscopic extranodal extension in oral cavity squamous cell carcinoma is associated with worse overall survival than patients without extranodal extension following primary surgical intervention with neck dissection. The results of this study also suggest that the addition of chemotherapy to adjuvant radiation may not provide a significant survival benefit in patients with oral cavity squamous cell carcinoma with microscopic and macroscopic extranodal extension. Comprehensive assessment of the benefits of adjuvant chemoradiation in the setting of microscopic vs macroscopic extranodal extension would need to be studied in a randomized controlled trial.