International multicentric validation of a novel T classification system for cancer of the nasal vestibule

Study aim: Cancer of the nasal vestibule (CNV) is an underrecognized head and neck malignancy, lacking a distinct ICD-O-3 topography code, and a specific T classification. The goal of this study was to assess which of the currently used T classifications provides the most accurate predictive and discriminatory accuracy. Methods: The four currently used classifications (UICC Sinonasal, UICC NMSC, Wang and Rome) were assessed in a retrospective multicenter cohort established within the Head & Neck and Skin Groupe Européen de Curiethérapie / European SocieTy for Radiotherapy & Oncology Working Group. Through multivariable disease-specific and recurrence-free survival analyses, it was evaluated which staging system was most valuable. Results: 609 CNV cases were retrieved from 21 tertiary care centers. Only the Wang and New Rome systems provided accurate prognostic stratification as they showed diminishing survival rates and increasing hazards of disease-specific death and disease recurrence with each successive T category. Compared to Wang, the New Rome system employs more objective criteria and, since it includes four T categories, it can easily be integrated with cN stage to obtain a specific clinical staging for the CNV, which has also resulted superior compared to the current UICC/AJCC systems in this study. Conclusion: The New Rome classification exhibits a superior predictive and descriptive precision compared to the Wang and both UICC/AJCC systems. The New Rome's T category structure would allow an integration into the wider UICC/AJCC system once the nasal vestibule is acknowledged as a different subsite.