Prognostic value of the 8th edition American Joint Commission Cancer nodal staging system for patients with head and neck cutaneous squamous cell carcinoma: A multi-institutional study

Background The 8th edition American Joint Committee on Cancer staging manual (AJCC8) introduced a separate staging system for head and neck cutaneous squamous cell carcinoma (HNcSCC) which parallels mucosal SCC and incorporates extranodal extension (ENE). This study aims to evaluate its prognostic utility. Methods Univariate analysis of 1146 patients with metastatic HNcSCC from four Australian cancer centers was performed according to both AJCC 7th (AJCC7) and the 8th editions. Results AJCC8 increased classification of 924 (80.6%) patients to either pN2a or pN3b and 341 patients (29.8%) from stage III to IV compared to AJCC7. The disease-specific survival (DSS) was not significantly different between pN1, pN2 or pN3a categories per AJCC8. Estimates of model performance for the AJCC8 pN staging revealed modest predictive capacity (Harrell's C of 0.62 for DSS). Conclusions The risk stratification according to pN classification of AJCC8 staging system performed poorly as a prognostic indicator.