Predictive value of the 8th edition American Joint Commission Cancer (AJCC) nodal staging system for patients with cutaneous squamous cell carcinoma of the head and neck

Background: The 8th edition American Joint Committee on Cancer (AJCC8) provides the same nodal staging system for mucosal and cutaneous squamous cell carcinoma of the head and neck (HNcSCC) and includes extranodal extension (ENE) as an adverse prognostic criterion. This study evaluates the prognostic efficacy of the AJCC8 pathologic nodal staging system (pN) for HNcSCC. Methods: Univariate analysis of 382 patients with metastatic HNcSCC staged according to both the 7th (AJCC7) and the 8th edition staging systems. Results: The AJCC7 pN3 category was associated with reduced disease specific survival (DSS HR 5.49; 95% CI: 1.83-16.53; P = 0.002) and overall survival (OS HR 3.42; 95% CI: 1.54-7.58; P = 0.002) as compared with pN1. However, no difference was observed between pN1, pN2, and pN3 categories as defined by the AJCC8. Also, when comparing Stages III and IV as defined by AJCC8, there was no difference in DSS (HR 0.75; 95% CI: 0.34-1.67; P = 0.478) or OS (HR 0.88; 95% CI: 0.51-1.51; P = 0.648). Conclusion: The AJCC8 performed poorly as a prognostic indicator for patients with metastatic HNcSCC in this cohort. HNcSCC would benefit from a staging system that accounts for its unique biologic characteristics distinct from mucosal SCC