Postoperative staging of the neck dissection using extracapsular spread and lymph node ratio as prognostic factors in HPV-negative head and neck squamous cell carcinoma patients

Abstract

Objectives: The presence of nodes with extracapsular spread (ECS) and the lymph node ratio (LNR) have prognostic competence in the pathologic evaluation of patients with a head and neck squamous cell carcinoma (HNSCC) treated with a neck dissection. The purpose of this study is to assess the effect of ECS & LNR on prognosis of HPV negative HNSCC patients treated with neck dissection and to compare to 8th edition TNM/AJCC classification.

Materials and methods: We carried out a retrospective study of 1383 patients with HNSCC treated with a neck dissection between 1985 and 2013. We developed a classification of the patients according to the presence of nodes with ECS and the LNR value with a recursive partitioning analysis (RPA) model.

Results: We obtained a classification tree with four terminal nodes: for patients without ECS (including patients pN0) the cut-off point for LNR was 1.6%, while for patients with lymph nodes with ECS it was 11.4%. The 5-year disease-specific survival for patients without ECS/LNR < 1.6% was 83.3%; for patients without ECS/LNR ≥ 1.6% it was 61.5%; for patients with ECS/LNR < 11.4% it was 33.7%; and for patients with ECS/LNR ≥ 11.4% it was 18.5%. The classification obtained with RPA had better discrimination between categories than the 8th edition of the TNM/AJCC classification.

Conclusion: ECS status and LNR value proved high prognostic capacity in the pathological evaluation of the neck dissection. The combination of ECS and LNR improved the predictive capacity of the 8th edition of the TNM/AJCC classification in HPV-negative HNSCC patients.

Keywords: Extracapsular spread; HPV-negative; Head and neck cancer; Lymph node ratio; TNM classification; pN.