Extracapsular extension is associated with worse distant control and progression-free survival in patients with lymph node-positive human papillomavirus-related oropharyngeal carcinoma

Objectives: To determine the prognostic utility of pathologic extracapsular extension (ECE) in human papillomavirus (HPV) associated oropharyngeal squamous cell carcinoma (OPSCC). Materials and Methods: Retrospective analysis was performed on patients who underwent surgery for primary HPV-related OPSCC and received adjuvant radiotherapy (RT) between 2006 and 2015. Locoregional control (LRC), distant control (DC), progression-free survival (PFS) and overall survival (OS) were compared between the groups with and without ECE using univariate Kaplan-Meier and multivariate Cox regression survival analyses. Results: 75 patients were identified and ECE was demonstrated on the surgical pathology of 26 patients. ECE(+) patients more frequently received chemotherapy (76.9% vs. 32.7%; p < 0.0001) and RT doses > 66 Gy (76.9% vs. 16.3%; p < 0.001). With a median follow-up of 29 months, patients with ECE had a significantly worse 5-year DC rate than those without ECE (76.7% vs. 97.9%; p = 0.046), and patients with ECE had a significantly worse 5-year PFS (54.5% vs. 93.6%; p = 0.021) than those without ECE. On multivariate Cox regression analysis, ECE was independently prognostic of worse DC (hazard ratio: 8.26; 95% confidence interval: 1.24-55.21; p = 0.029) and worse PFS (HR: 4.64; 95% CI: 1.18-18.29; p = 0.028). There was no statistically significant difference in 5-year LRC (93.3% vs. 95.7%) or OS (66.9% vs. 97.0%) between ECE(+) and ECE(-) patients, respectively. Conclusion: This study suggests that ECE is independently prognostic of worse DC and PFS in patients who undergo surgery prior to adjuvant RT for primary HPV-related OPSCC.