Prognostic Significance of Lymph Node Ratio after Cervical Lymph Node Dissection in Head and Neck Squamous Cell Carcinoma

Background: Lymph node ratio (LNR) is the number of positive lymph nodes (LNs) divided by the total number of excised nodes. It has been shown to be of prognostic significance in a number of cancers. Aim: To investigate the relation between LNR and survival of patients with head and neck squamous cell carcinoma (HNSCC). Methods: A retrospective study of 115 patients with HNSCC treated with curative surgery including neck dissection ± adjuvant treatment from January 2013 to December 2017. Results: The median LNR among node-positive patients was 0.14 which was used as a cutoff point to divide patients into two risk groups. Male gender, N2 stage, high grade and extranodal extension were significantly associated with high (≥0.14) LNR. In multivariate analysis, high LNR, higher TNM nodal stage and larger absolute number of positive LNs associated significantly with worse overall and disease-free survival. In a subgroup analysis of node-positive cases (n=54), LNR associated significantly with disease-free survival but not overall survival.  On the other hand, the absolute number of positive LNs and N stage had a significant effect on both overall and disease-free survival. Conclusion: The LNR is of prognostic significance for survival and disease failure in HNSCC. This is also true for the absolute number of positive LNs. Standardization of LN status assessment and determination of an agreed upon cutoff value for LNR are needed before considering its incorporation in the staging system and treatment strategy.