Advancing Education, Research, and Quality of Care for the Head and Neck oncology patient.
Background: Human papillomavirus (HPV) associated oropharyngeal squamous cell carcinoma (OPSCC) is rapidly increasing in incidence across the United States. In 2017, the American Joint Committee on Cancer (AJCC) released the 8th edition staging system, which reported separate clinical and pathologic staging systems for HPV-related OPSCC. Based on multicenter data, pN staging was dependent on metastatic node number. The aim of this study was first, to analyze in a large cohort the impact of metastatic node number on OS for SRHPVOPSCC patients with or without adjuvant therapy, and second to analyze potential associations between node number and extranodal extension (ENE).
Methods: The National Cancer Database (NCDB) was queried from 2010 to 2018, for patients with HPV-related OPSCC who underwent resection of the primary site and neck dissection(s), with a minimum of 10 nodes examined. Patient clinical and demographic were collected, including 8th edition T and N staging as well as adjuvant treatment. Pathologic data included primary site margin status, positive nodes, ENE, and lymphovascular invasion. The primary outcome was OS. Different groupings of progressively increasing positive node numbers were analyzed for significance at the univariable level, and multivariable analyses were performed using Cox proportional hazards ratios (HR) with 95% confidence intervals (CI).
Results: We identified 9,925 patients. The median age was 59 years, and the majority of patients were White (94.41%) and male (86.77%). 62.37% were reported from academic institutions. On final pathology, 84.09% had 0-4 nodes positive, 7.29% had 5-6 nodes positive, and 8.61% had more than 6 nodes positive. Univariate analysis of node number revealed an increase in HR as node number increased incrementally from 1 to 10 or more. Multivariate analysis revealed that, compared to 0-4 positives nodes, 5-6 positive nodes were associated with a HR of 1.58 (CI 1.32-1.90, p < 0.0001), and >6 positive nodes were associated with a HR of 2.12 (CI 1.83-2.46, p <0.0001). Patients with higher numbers of positive nodes were more likely to receive adjuvant chemoradiation rather than radiation alone.
ENE was identified in 40.03% of cases and associated with worse OS. ENE positivity had an approximately linear relationship with increasing positive node number, ranging from 32.68% for 1 positive node to 76.88% for greater than 10 positive nodes.
Conclusion: In surgically resected HPV-related OPSCC, increased pathologic node numbers are associated with worse overall survival and covaries with frequency of ENE. While the majority of patients had 0-4 positive nodes, there was a significant decrease in OS in patients with 5-6 and >6 positive nodes even while using adjuvant chemoradiation more frequently. Further study of patients with higher pathologic node numbers is warranted with potential adjustment of the current staging system.