Adjuvant Radiotherapy in Surgically Treated HPV-Positive Oropharyngeal Carcinoma with Adverse Pathological Features.

Purpose: HPV-positive oropharyngeal carcinoma (HPV-OPC) is increasingly treated with primary surgery. The National Comprehensive Cancer Network (NCCN) recommends adjuvant therapy for surgically treated HPV-OPC displaying adverse pathological features (AF). We evaluated adjuvant radiotherapy patterns and outcomes in surgically treated AF-positive HPV-OPC (AF-HPV-OPC). Methods: The National Cancer Database was interrogated for patients ≥ 18 years with early-stage HPV-OPC from 2010 to 2017 who underwent definitive resection. Patients that had an NCCN-defined AF indication for adjuvant radiotherapy were assessed, including positive surgical margins (PSM), extranodal extension (ENE), lymphovascular invasion, and level 4/5 cervical lymph nodes. Overall survival (OS) was evaluated using Cox proportional hazards models and Kaplan−Meier analysis in whole and propensity score matched (PM) cohorts. Results: Of 15,036 patients meeting inclusion criteria, 55.7% were positive for at least one AF. Presence of any AF was associated with worse OS (hazard ratio (HR) = 1.56, p < 0.001). In isolation, each AF was associated with worse OS. On PM analysis, insurance status, T2 category, Charlson-Deyo comorbidity score, ENE (HR = 1.81, p < 0.001), and PSM (HR = 1.58, p = 0.002) were associated with worse OS. Median 3-year OS was 92.0% among AF-HPV-OPC patients undergoing adjuvant radiotherapy and 84.2% for those who did not receive adjuvant radiotherapy (p < 0.001, n = 1678). The overall rate of patients with AF-HPV-OPC who did not receive adjuvant radiotherapy was 13% and increased from 10% in 2010 to 17% in 2017 (ptrend = 0.007). Conclusions: In patients with AF-HPV-OPC, adjuvant radiotherapy is associated with improved survival. In the era of de-escalation therapy for HPV-OPC, our findings demonstrate the persistent prognostic benefit of post-operative radiotherapy in the setting of commonly identified adverse features. Ongoing clinical trials will better elucidate optimized patient selection for de-escalated therapy.