Prognostic value of the lymph node ratio in oropharyngeal carcinoma stratified for HPV-status.

Abstract

Lymph node ratio (LNR) was shown to be a prognostic factor in laryngeal and oral cavity primaries. The purpose of this study was to investigate the impact of the lymph node ratio in oropharyngeal squamous cell carcinoma (OPSCC) with a high incidence of HPV-related disease. Therefore, the role of LNR was evaluated as an additional predictive parameter to the 8th edition of AJCC TNM staging system. From December 2009 to August 2015, patients diagnosed with primary oropharyngeal squamous cell carcinoma were prospectively enrolled. After tumor resection with uni- or bilateral neck dissection, patients with ≥ 1 nodal metastasis (pN+) were eligible for a retrospective LNR analysis. 137 patients underwent tumor resection with uni- or bilateral neck dissection. The proportion of HPV-associated disease was 42%. Most patients (n = 96; 70%) presented with involved neck nodes. In p16-positive OPSCC, the rate of pN + cases was significantly increased compared to p16-negative OPSCC (86% vs. 58%, p = 0.007). Patients with LNR ≤ 10% had a significant better overall survival (OS) and disease-specific survival (DSS). However, when stratified for p16-status, LNR ≤ 10% had a significant impact on OS only for HPV-associated tumors (p = 0.027), whereas LNR of ≤ 10% was not a significant predictor for better OS in p16-negative OPSCC (p = 0.143). The LNR with a cut-off value of 10% serves as an additional prognostic parameter in HPV-related OPSCC and may help to improve risk stratification in combination with the revised AJCC 8th edition TNM classification.