Impact of Lymph Node Yield on Survival in Surgically Treated Oropharyngeal Squamous Cell Carcinoma

Abstract

Objectives (1) To estimate the association between neck dissection lymph node yield (LNY) and survival among patients with surgically treated human papilloma virus (HPV)–associated oropharyngeal squamous cell carcinoma (OPSCC). (2) To identify a clinically relevant quality metric for surgical treatment of HPV-related OPSCC. Study Design Retrospective cohort study. Setting National Cancer Database. Subjects and Methods From the National Cancer Database, 4130 patients were identified with HPV-associated OPSCC treated with primary surgery from 2010 to 2016. Based on prior literature, an adequate neck dissection LNY was defined as ≥18 lymph nodes. To determine whether LNY is associated with survival, univariable and multivariable Cox proportional hazards regression was performed. Analysis was stratified by adjuvant therapy regimen. Results A total of 2113 patients (51.2%) underwent surgery with or without adjuvant radiation (S ± RT), and 2017 patients (48.8%) underwent surgery with adjuvant chemoradiation. LNY ≥18 was associated with a 5-year survival benefit of 7.15% (91.7% for LNY ≥18, 84.5% for LNY <18, P = .004) for the S ± RT cohort on unadjusted survival analysis. For the S ± RT group, LNY ≥18 was associated with decreased hazard of death (hazard ratio, 0.45; 95% CI, 0.29-0.70; P < .001) after adjustment for patient characteristics, TNM staging, surgical margins, extranodal extension, and treating facility characteristics. For surgery with adjuvant chemoradiation, the adjusted hazard ratio estimate for LNY ≥18 was 0.64 (95% CI, 0.41-1.00), but the result was not statistically significant ( P = .052). Conclusion An adequate LNY from a neck dissection may affect survival when HPV-related OPSCC is treated with up-front surgery.