Population-based validation of the recursive partitioning analysis-based staging system for oropharyngeal cancer.

BACKGROUND: The American Joint Committee on Cancer (AJCC) staging system does not adequately distinguish prognostic groups in the era of human papillomavirus (HPV)-related oropharyngeal cancer. The purpose of this study was to validate a recursive partitioning analysis (RPA)-based stage grouping on a population-wide level. METHODS: We identified 8427 patients in Surveillance, Epidemiology, and End Results (SEER) with nonmetastatic oropharyngeal cancer with unknown HPV-status diagnosed from 2004 to 2008. We estimated the overall survival (OS) and head and neck cancer-specific mortality by RPA stage and AJCC stage and compared the predictive power of the systems. RESULTS: RPA stage was significantly associated with OS and head and neck cancer-specific mortality (p < .0001) with 5-year OS of 70% for RPA-I, 55.6% for RPA-II, and 44.3% for RPA-III. AJCC stage failed to divide patients into distinct subgroups. RPA stage had significantly improved predictive ability versus AJCC stage for OS (c-statistic: 0.60 = RPA vs 0.54 = AJCC) and head and neck cancer-specific mortality (c-statistic: 0.62 = RPA vs 0.55 = AJCC). CONCLUSION: The RPA-based stage grouping divided patients into prognostically distinct cohorts and provided superior prediction of OS and head and neck cancer-specific mortality compared to AJCC staging. (c) 2016 Wiley Periodicals, Inc. Head Neck 38: First-1538, 2016.