Extranodal Extension Improves AJCC-8 Accuracy in HPV plus Oropharyngeal Cancer in a High-Risk Population

Objectives: The American Joint Committee on Cancer's 8th edition (AJCC-8) separates oropharyngeal squamous cell carcinomas (OPSCCs) into human papillomavirus-positive (HPV+) tumors and HPV-negative tumors. Although AJCC-8 improves prognostic prediction for survival for the majority of HPV+ OPSCC, outliers are still encountered. The goal of this manuscript is to validate the AJCC-8 as a better metric of survivability than the AJCC-7 in an historically under-served rural population with confounding variables, such as tobacco use, alcohol consumption, and poor health care access and to analyze the role of extranodal extension (ENE) in this population.Design: Retrospective cohort study.Results: Compared to AJCC-7, AJCC-8 had a higher odds ratio (OR) for predicting mortality of stage IV HPV+ OPSCCs versus stages I-III. On multivariate analysis, HPV+ OPSCCs with ENE had a higher OR of mortality compared to ENE- OPSCCs. In addition, HPV+ OPSCC patients with a Charlson Comorbidity Index (CCI) > 3 had a higher OR of mortality compared to those with a CCI & LE; 3. Patients with Medicaid/self-pay status had a higher OR of mortality compared to those with private insurance/Medicare. Finally, patients from rural populations had a higher OR of presenting with stage IV disease, a CCI > 3, and Medicaid/self-pay status.Conclusions: Despite not being a discrete part of the AJCC-8 staging rubric, ENE was found to have a significant impact on mortality among this population, whereas tobacco use had no effect. Rural patients were more likely to present with stage IV disease, CCI > 3, and Medicaid/self-pay status. Stage IV disease was also associated with a higher OR of mortality.