Radiologic Extranodal Extension Portends Worse Outcome in cN+ TNM8 Stage I Human Papillomavirus-Mediated Oropharyngeal Cancer

Abstract Objective To identify adverse radiologic nodal features in cN+ TNM8 stage I HPV-related (HPV+) oropharyngeal cancer (OPC). Methods All HPV+ cT1-T2cN1 OPC patients treated with definitive IMRT from 2008-2015 were included. Radiologically involved lymph node (LN) number, radiologic extranodal extension (rENE), retropharyngeal (RPLN) and lower neck (Level 4/5b) LNs involvement were assessed on pre-IMRT CT/MR by a specialized head-and-neck neuroradiologist. Disease-free survival (DFS), locoregional (LRC) and distant control (DC) were compared between those with vs without rENE. Univariable and multivariable analysis with step-wise modal selection were applied to identify prognostic factors for DFS. Results A total of 45 rENE+ and 234 rENE– were identified. The rENE+ cohort had a higher number of LNs per patient [median: 6 vs 2, p Conclusion Data from this contemporaneously-treated cT1-T2N1 HPV+ OPC cohort suggests that the presence of rENE is an independent prognostic factor within Stage I HPV+ OPC. RPLN is also associated with DM risk but not with DFS.