Validation of the pathological classification of lymph node metastasis for head and neck tumors according to the 8th edition of the TNM Classification of Malignant Tumors

Abstract

Objectives: One of the main changes in the 8th edition of the TNM Classification for head and neck tumors is the inclusion of extracapsular spread (ECS) as a criterion for evaluating the regional extension, both clinical (cN) and pathological (pN). The objective of our study is to evaluate the prognostic capacity derived from the inclusion of the ECS in the pathological classification of head and neck squamous cell carcinoma (HNSCC) patients treated with a neck dissection, as established by the 8th edition TNM Classification.

Materials and methods: Retrospective study of 1188 patients with HNSCC treated with a neck dissection between1990 and 2013.

Results: There were lymph node metastasis in 50.1% of the neck dissections. The pathological record revealed ECS in 50.5% of the positive neck dissections. The implementation of the changes of the 8th edition TNM classification produced the upstaging of 20.9% of the patients classified as pN1 with the 7th edition TNM classification to pN2a¸ and the upstaging of 58.4% of the patients classified as pN2 with the 7th edition TNM classification to pN3b. We conducted an objective comparison of the quality of both classifications. The 8th TNM classification edition achieved better results regarding both the discrimination in cause-specific survival between pN categories and in the distribution in the number of cases between categories than the 7th edition TNM classification.

Conclusion: The inclusion of ECS in the pathological classification (pN) of the neck nodes improves the prognostic capacity of the 8th TNM Classification edition.

Keywords: Extracapsular spread; Head and neck cancer; Neck node metastasis; TNM Classification; pN.