Neck dissection of Level Ib for the treatment of cN0 HPV-negative oropharyngeal squamous cell carcinoma: Should it be safely omitted?

Abstract

Abstract Background: Selective neck dissection (SND) of levels II-IV is traditionally recommended for the treatment of cN0 oropharyngeal squamous cell carcinoma (OPSCC). Whether to include level Ib in the dissection of cN0 neck tumors is debated because occult lymph node metastasis is frequently located at level II, which is closely posterior to level Ib. Moreover, neck dissection focusing on HPV-negative OPSCC is insufficient because the HPV-positive subtype accounts for most cases in many regions, especially in Western countries. The aim of this study was to clarify whether patients would potentially benefit from including level Ib in SND for cN0 HPV-negative OPSCC. Methods: This retrospective cohort study included 198 cN0 HPV-negative OPSCC patients who underwent SND of levels II-IV (Group A) and levels Ib-IV (Group B). Neck recurrence (NR) was considered the primary endpoint. Overall survival (OS), disease-free survival (DFS), and disease-specific survival (DSS) were the secondary endpoints. Results: In Group B, the rate of occult lymph node metastasis at level Ib of the ipsilateral neck was 6.1%. For the entire cohort, the rate of NR was 7.6% in Group A and 2.3% in Group B (p = 0.074). The 5-year OS and DFS rates were also not significantly different between Group A (50.0% and 43.2%) and Group B (57.6% and 51.6%), while Group B had higher 5-year DSS rate than Group A (60.7% vs. 47.9%, p = 0.018). For the tumor from the base of tongue, the rate of NR was obviously higher in Group A (12.2%) than in Group B (2.1%, p = 0.015). Patients in Group A had lower 5-year DFS (39.1% vs. 47.4%, p = 0.046) and DSS rates (46.5% vs. 56.3% p = 0.034). N2 stage was an independent predictive factor for both OPSCC (p= 0.017) and the primary tumor from the base of tongue (p = 0.007). Conclusions: Even though the metastatic rate of cN0 OPSCC at level Ib was relatively low, including level Ib in SND should be considered for OPSCC originating from the base of tongue, especially in advanced stages, which would potentially lower the rate of NR and improve the survival benefit.