Tumor cell viability in salvage neck dissections: Poor prognosis predicted by high postradiation nodal SUVmax , p16-negativity, and low nodal shrinkage.

Abstract

After primary chemoradiation in advanced oropharyngeal, laryngeal, and/or hypopharyngeal cancer, nodal disease may require a salvage neck dissection. However, salvage neck dissection is associated with increased morbidity and may only be necessary in case of persistence of viable tumor cells, which can be difficult to confirm and virtually impossible to exclude by fine needle aspiration cytology. We, therefore, aimed to identify predictive factors for the persistence of viable tumor cells in lymph node metastases from head and neck squamous cell cancer after chemoradiation. We performed a retrospective review of neck dissection specimens performed after primary (chemo-)radiation for oropharyngeal, laryngeal, or hypopharyngeal squamous cell carcinoma. All patients were treated at University Hospital Zurich from 2007 to 2016. A total of 78 patients were included. Thirty-eight patients (48.7%) had viable tumor cells in their neck dissection sample. High postradiation nodal maximum standardized uptake value (SUVmax ), p16 negativity, and low nodal shrinkage were predictors of viable tumor cells in salvage neck dissections (Mann-Whitney U/chi-squared test, P < .001, P = .025, and P = .042, respectively). Patients with viable tumor cells showed a significantly worse locoregional recurrence-free survival, distant metastasis-free survival, and disease-specific survival (log-rank test, P < .001). Viable tumor cells can be predicted by high residual metabolic activity in the lymph nodes, negative p16 status, and low nodal shrinkage. Viable tumor cells in neck dissection specimens are associated with a poor survival and provide important prognostic information.