Comparison of the AJCC N staging system in mucosal and cutaneous squamous head and neck cancer.

OBJECTIVES/HYPOTHESIS: The American Joint Committee on Cancer (AJCC) substantially changed the staging of cutaneous squamous cell carcinoma (cSCC) in the seventh edition of its staging manual. Given that oral mucosal squamous cell carcinoma (mSCC) and cSCC behave differently and affect different patient populations, the aim of this study was to provide a side-by-side comparison and to evaluate the current nodal (N) grouping for cSCC alongside oral mSCC to determine whether the same system is justified. STUDY DESIGN: Retrospective analysis of prospectively collected data. METHODS: Multivariable analysis of 672 patients with metastatic cSCC and of 225 patients with metastatic mSCC from two prospective cancer-center databases. RESULTS: While, as expected, the N grouping functioned well in mSCC in terms of distribution and stratification of patients, it performed much less favorably in cSCC. In contrast to mSCC, the different N groups demonstrate much less prognostic importance in cSCC. CONCLUSION: Although the introduction of a unified N system for mSCC and cSCC has definite advantages, it does not translate into optimal distribution and stratification for metastatic cSCC. LEVEL OF EVIDENCE: 4.