Prognostic value of lymph node ratio versus American Joint Committee on Cancer N classification for surgically resected human papillomavirus-associated oropharyngeal squamous cell carcinoma.

Background: We compared prognostic values of lymph node ratio (LNR) and AJCC 8 N classification in surgically resected human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma (OPSCC).

Methods: Using the National Cancer Database, we identified patients with HPV-associated OPSCC from 2010 to 2016 who underwent definitive surgical resection. Patients were analyzed by nodal grouping (LNR, N stage) and adjuvant radiation therapy(RT). Primary endpoint was overall survival.

Results: We identified 4166 patients. Survival analysis showed significant improvement for LNR≤6% versus >6% (5 year OS% 92.7% vs. 83.7%, p < 0.001). N classification demonstrated good prognostic ability (5 year OS% for pN0, pN1, pN2 were 91.3%, 90.1%, 78.8%, p < 0.001), but poor separation among stages (compared to pN0: pN1 HR 1.40 [95% CI 0.63, 3.09], p = 0.41; pN2 HR 2.50 [95% CI 1.08, 5.81], p = 0.033). RT improved survival in the LNR > 6% group (5 year OS% 85.4% vs. 74.9%, p < 0.001; HR 0.41 [95% CI 0.28, 0.58], p < 0.001).

Conclusions: LNR should be considered an adjunct category in future staging systems for HPV-associated OPSCC.