Occult nodal metastasis in surgically treated HPV-related oropharyngeal squamous cell carcinoma

Presentation: AHNS39
Topic: Oropharynx / HPV Related Disease
Type: Oral
Date: Thursday, April 28, 2022
Session: 11:15 AM – 12:00 PM Oropharynx HPV
Authors: Austin C Cao, BA; Erin R Cohen, MD; Robert M Brody, MD
Institution(s): University of Pennsylvania Department of Otorhinolaryngology- Head and Neck Surgery


Objective:

 (1) To describe the incidence and predictors of radiographic occult nodes in patients with clinically node negative (cN0) HPV-related oropharyngeal squamous cell carcinoma (OPSCC) and treated with primary surgery.

Study Design: Retrospective cohort study.

Methods: Retrospective review of patients presenting to a tertiary care center with cN0 HPV-related OPSCC and treated with primary trans-oral robotic surgery (TORS) from March 2007 to March 2021 was performed. Data included patient demographics, diagnostic imaging, histopathology, and survival outcomes. Analyses using the Kaplan-Meier method, and univariate and multivariate logistic regression were performed to assess for variables predictive of pathologic nodal disease.

Results: Seven hundred seventy-eight patients were included, with 112 presenting as cN0 following diagnostic work-up. The median age at surgery was 63 (IQR: 59-69) and 88 (79%) were male. Regional disease was assessed with a battery of imaging modalities, including CT with contrast in 75 patients (67%), MRI with/without contrast in 31 (27.7%), and PET/CT in 58 (52%), non-exclusively. The incidence of a pathologic positive node on ipsilateral neck dissection was 32%. Four percent of cN0 patients had level 4 or 5 involvement and 8% had extracapsular extension. Sixty-six percent of patients were treated with surgery only, 21% with adjuvant radiation, and 13% with adjuvant chemoradiation. Of the 10 of patients who underwent bilateral neck dissection, no contralateral occult nodes were found. Contralateral neck dissection was indicated in 9/10 patients due to base of tongue primary, and all subsequently did not require adjuvant therapy. Disease-free survival at 3 years was equivalent between cN0 and cN1-3 patients (72.5% vs. 71.4%, p = 0.120). Late tumor stage, lymphovascular invasion, and perineural invasion (OR 2.13, p = 0.022; OR 1.82 p = 0.044; OR 2.86, p = 0.048, respectively) were predictive of pathologic positive nodes in cN0 patients. The use of only one diagnostic imaging modality, or the exclusion of any specific imaging modality, were not found to be associated with a pathologic positive node. 

Conclusion: Here we demonstrate that occult regional metastasis to ipsilateral cervical nodes is prevalent in HPV+ OPSCC. Advanced primary tumor characteristics are predictors of occult nodes, while type of diagnostic imaging used was not. Contralateral neck dissection in patients with base of tongue tumors has a low yield for radiographic occult nodes.