Impact of contralateral lymph nodal involvement and extranodal extension on survival of surgically managed HPV-positive oropharyngeal cancer staged with the AJCC eighth edition

Abstract

Objectives: Contralateral lymph node (LN) involvement is a prognostic factor in clinical staging of oropharyngeal squamous cell carcinoma (OPSCC), while pathologic nodal staging in the AJCC 8th edition for human papillomavirus-mediated OPSCC (HPV + OPSCC) focuses exclusively on the number of involved LNs (pLN+). This study assessed if the presence of contralateral pLN+ adds prognostic importance to the number of pLN+.

Materials and methods: The National Cancer Database was queried for pLN+ HPV + OPSCC treated with surgery with 10 or more LN dissected. Data were evaluated with Cox regression, propensity score matching (PSM), and Kaplan-Meier overall survival (OS) analysis.

Results: Of 3407 patients, 152 (4.5%) patients had contralateral pLN+. Subjects with contralateral pLN+ had higher pT/pN stage, more positive margins, extranodal extension (ENE), and lymphovascular invasion (LVI) (all p < 0.05). On univariate analysis, contralateral pLN+ trended toward worse OS (HR 1.58, 95% CI 0.98-2.55, p = 0.061). In the multivariable model (controlling for age, comorbidities, T-stage, N-stage, LN size, ENE, LVI, margin status and adjuvant therapy), LN laterality had no impact on OS (HR 0.87, 95% CI 0.52-1.45, p = 0.520). Further PSM analysis confirmed that contralateral pLN+ is not associated with OS in this population (HR 0.79, 95% CI 0.41-1.53, p = 0.494).

Conclusion: This study supports the AJCC 8th edition pathologic staging for HPV + OPSCC by observing that LN laterality is not associated with OS. ENE was associated with inferior OS and should be considered for future staging systems. Further study should be directed at the importance of nodal size in this population.

Keywords: AJCC 8th edition; Extranodal extension; Human papillomavirus; Lymph nodes; Oropharyngeal cancer; Staging; Survival.