© 2017 American Cancer Society BACKGROUND: Extranodal (or extracapsular) extension (ENE) is an adverse prognostic factor in patients with head and neck cancers who undergo primary surgery. However, the significance of ENE in human papillomavirus (HPV)-positive oropharyngeal squamous cell carcinoma (OPSCC) is not well established, and single-institution studies have not established that ENE predicts inferior outcome. The authors investigated the prognostic value of ENE in HPV-positive patients who underwent primary surgery and whether adjuvant chemoradiation improved overall survival (OS) compared with radiation alone in ENE-positive patients. METHODS: Patients who underwent primary surgery for pathologic T1 (pT1) through pT4 tumors, pathologic N1 (pN1) through pN3 lymph node status, HPV-positive OPSCC were identified in the National Cancer Data Base from 2010 through 2012. Features associated with ENE were analyzed. Univariable and multivariable Cox regression analyses identified predictors of OS. The effect of adjuvant treatment on OS in ENE-positive cohort was also evaluated. RESULTS: In total, 1043 patients met inclusion criteria, among whom 43.5% were ENE-positive. Of the ENE-positive patients who had treatment details available, 72% received concurrent chemoradiotherapy, 16% received radiotherapy, and 12% received no adjuvant treatment. After a median follow-up of 28.4 months, ENE was associated with worse 3-year OS (89.3% vs 93.6%; P =.01). On multivariable analysis that included involved lymph nodes, only ENE, lymphovascular invasion, pT3/pT4 tumors, and Charlson-Deyo score were associated with worse OS. Among ENE-positive patients, there was no difference in 3-year OS between those who received adjuvant concurrent chemoradiotherapy versus radiotherapy alone (89.6% vs 89.3%, respectively; P =.55). Propensity score-matched comparison revealed similar results. CONCLUSIONS: ENE is associated with inferior OS in patients with HPV-positive OPSCC. However, OS was not better with adjuvant chemoradiotherapy compared with radiotherapy alone in ENE-positive patients. The current findings support the need for prospective studies of adjuvant chemoradiation in HPV-positive patients with ENE. Cancer 2017;123:2762-72. © 2017 American Cancer Society.