Staging of oropharyngeal squamous cell carcinoma of the head and neck: Prognostic features and power of the 8th edition of the UICC staging manual

Abstract

Introduction: Recognizing the prognostic power differentiating HPV-associated oropharyngeal squamous cell cancer (OPSCC) from OPSCC with other causes, the UICC Cancer Staging Manual 8th edition realizes significant changes from the 7th edition. Purpose of this study was to evaluate the differences of prognostic impact between the 7th and the latest edition of TNM Classification as well as to examine risk factors like extranodal extension (ENE) and lymph node ratio (LNR) for HPV-mediated OPSCC.

Material and methods: The study includes 255 patients with OPSCC and initial diagnosis between 2008 and 2015. HPV status was determined according to p16 immunohistochemistry (IHC) and all patients were classified as defined by 7th and 8th edition of UICC. Prognostic influence of ENE and LNR was analyzed for patients with HPV-mediated OPSCC.

Results: 41.2% of the OPSCC were p16-positive. Implementation of the 8th edition of the UICC lead to a better differentiation between the respective stages. Regarding HPV-positive OPSCC, Kaplan-Meier survival curves showed a significantly better overall survival (OS) for patients with a LNR ≤10% as well as for patients with negative ENE status (p = 0.004, p = 0.008).

Conclusion: 8th edition of UICC achieves to differentiate properly between the UICC stages. However, the staging rule of ignoring ENE in HPV-mediated OPSCC should be further analyzed. Moreover LNR might be a possible additional prognostic factor - especially regarding HPV-positive tumors.

Keywords: Extranodal extension; HPV; Lymph node ratio; Oropharyngeal cancer; TNM staging.