Long-term outcome of cervical lymph node metastasis in superficial pharyngeal squamous cell carcinoma after endoscopic submucosal dissection.

BACKGROUND AND AIMS: Superficial pharyngeal squamous cell carcinoma (PSCC) has received increasing attention as a therapeutic target in the gastrointestinal field with recent innovations in endoscopic submucosal dissection (ESD). However, there are currently no defined criteria for the application of ESD to superficial PSCC. One of the problems encountered during follow-up post-ESD is cervical lymph node metastasis (LNM). Identifying the clinicopathological predictors of cervical LNM can help to provide a basis for the refinement of therapeutic strategies for superficial PSCC.

METHODS: The risk of cervical LNM was evaluated in 331 patients with superficial PSCC who underwent initial ESD between 2008 and 2021. Since tumor size, rather than depth, is the dominant factor in the current TNM Classification for PSCC, the correlation between tumor size and thickness was investigated.

RESULTS: The median follow-up period was 4.8 years. The cumulative 5-year cervical LNM rate was 6.1%. Multivariate Cox proportional hazards regression analysis identified tumor thickness of ≥1000μm and lymphatic invasion as significant independent predictors. Among 204 cases with subepithelial invasion, both factors were also revealed to be significant independent predictors, suggesting that tumor thickness was superior to tumor size in predicting cervical LNM. Despite the positive correlation between tumor thickness and size, there was noticeable variability in the values (R=0.20), and the current staging was inadequate to identify groups at high-risk for cervical LNM.

CONCLUSIONS: Tumor thickness and lymphatic invasion are validated as significant independent predictors for cervical LNM, which can be useful indicators to optimize the therapeutic strategies for superficial PSCC.