Postoperative adjuvant chemoradiation versus adjuvant radiation in surgically managed HPV-mediated OPSCC: a ten-year study using 8th edition AJCC pathologic staging.

INTRODUCTION: HPV-mediated oropharyngeal squamous cell carcinoma (HPV+ OPSCC) is a disease associated with improved overall survival (OS). We explore the role and benefit of adjuvant chemoradiation in this population. METHODS: 9, 925 patients in the National Cancer Database (NCDB) who underwent definitive surgical treatment for HPV+ OPSCC followed by adjuvant treatment were included in the study. The primary outcome was OS. RESULTS: 4, 828 patients received adjuvant radiation (RT) and 5, 097 patients received adjuvant chemoradiation (CRT). There was no significant difference in OS between both groups. Increasing positive lymph node number increased the likelihood of patients receiving adjuvant CRT. In the proportional hazards model, patients with higher numbers of positive nodes had significantly reduced OS. The 5-6 positive node group was associated with a hazard ratio (HR) of 1.42 (CI: [1.15-1.75], p = 0.009) while > 6 positive nodes was associated with a HR of 2.19 (CI: [1.86-2.59], p < 0.001), when compared to 0-4 positive nodes. Multivariable analysis demonstrated no significant difference in OS between patients with ≤ 6 positive nodes with adjuvant CRT versus RT. The > 6 positive node group had significantly better OS with CRT versus RT. CONCLUSION: There was no observed difference in OS in surgically treated HPV+ OPSCC patients receiving adjuvant CRT versus adjuvant RT alone. Patients with higher positive node numbers were more likely to receive adjuvant chemotherapy, but no statistically significant survival benefit over RT was observed in patients with 0-6 involved nodes. Ongoing prospective trials should critically evaluate the role of adjuvant CRT in the postoperative management of HPV+ OPSCC.