Validation of the UICC 8th edition staging of oral cavity squamous cell carcinoma in a UK cohort

Abstract

The eighth edition of the Union for International Cancer Control (UICC) staging manual was recently introduced. The staging of oral cavity squamous cell carcinoma saw changes in relation to depth of invasion and extra-nodal extension. We aimed to evaluate this system and its prognostic ability in a UK cohort. A retrospective review was undertaken of patients diagnosed with squamous cell carcinoma (SCC) of the oral cavity between January 2009 and December 2013. Data were collected on demographics, histology, and recurrence-free (RFS) and five-year overall survival (OS). Patients were staged using both the seventh and eighth editions of the UICC staging manual. Stage-specific survival analysis was performed using the Kaplan-Meier method. A total of 191 records were reviewed and 87 were included in the analysis. The mean (range) age was 60 (37-88) years, and 53% were male. The tongue was the most common site (51%). Using the seventh edition patients were staged as stage I=30, II=14, III=7, IVa=35, and IVb=1. Applying the eighth edition, 26 patients (30%) were upstaged (I=24, II=15, III=14, IVa=17, IVb=17). Ten were upstaged based on pT and 16 on pN status. Both staging manuals showed statistically significant discrimination between stages for both OS and RFS. Patients upstaged from stage IVa in the seventh edition had significantly worse OS in the new system (p=0.043). Both staging systems discriminated accurately between stages. Patients upstaged in stage IVa showed significantly worse OS suggesting improved prognostication with the eighth edition and the changes introduced.