The Role of Radiotherapy to the Primary Site in Oropharyngeal Cancer with Limited Metastases-An Analysis of a Hospital-Based Registry.

Limited metastatic squamous cell carcinoma of the oropharynx (OPC) lacks clear management guidelines, especially for HPV-associated disease. The objective of this study was to investigate if primary site radiotherapy (RT) benefits overall survival in limited metastatic OPC. Utilizing the National Cancer Database (NCDB), patients aged 18-90 with OPC presenting as cM1 with limited metastatic disease to one distant site were identified. Propensity score matching, Cox-proportional hazards models, and Kaplan-Meier estimates were employed to assess factors associated with overall survival. In this study, 1056 patients were included with metastases involving bone (19.0%), brain (0.8%), lung (52.9%), liver (10.1%), and lymph nodes (20.4%). Treatment modalities included 54.6% receiving primary site RT, 45.4% receiving no RT, and 69.9% undergoing systemic therapy. For HPV-positive patients, RT (HR 0.64, = 0.0026) and receipt of chemotherapy (HR = 0.57, = 0.0057) were associated with improved overall survival, while bone and lung metastases were associated with decreased survival (HR = 1.75 and 1.39, = 0.0041 and 0.041, respectively). In HPV-negative cases, survival also correlated with RT (HR = 0.65, = 0.0047), receipt of chemotherapy (HR = 0.45, < 0.001), clinical T4 disease (HR = 1.99, = 0.012), presence of bone metastases (HR = 2.52, < 0.001), lung metastases (HR = 1.49, = 0.035), and lymphovascular invasion (HR = 1.10, < 0.001). Overall, patients who received RT showed increased median overall survival from 9.9 to 16.1 months ( < 0.001) compared to those who did not. When stratified by RT and HPV status, there was higher median survival for both HPV-positive (from 17.1 to 24.9 months, < 0.001) and HPV-negative patients (from 8.4 to 12.9 months, = 0.0016) who received RT compared to those who did not. Primary-site radiotherapy may positively impact overall survival in limited metastatic OPC, irrespective of HPV status.