Pathological Level VI Lymph Node Metastasis in Clinical N3b Pyriform Sinus Squamous Cell Carcinoma

Objective: The frequency of metastasis to level VI lymph nodes in advanced pyriform sinus squamous cell carcinoma (PSSCC) is unknown. We intended to analyze the clinical features and pathological presence or absence of level VI lymph node metastasis in patients with PSSCC. Methods: The data of 270 patients with previously untreated hypopharyngeal squamous cell carcinoma from 2006 to 2016 were obtained. Patients who underwent pharyngolaryngectomy for the pyriform sinus subsite with a curative intent with level VI dissection were included. We retrospectively analyzed the clinical Tumor-Node (TN) status (TNM classification of malignant tumors, eighth edition) and the presence or absence of pathological level VI lymph node metastasis. Results: A total of 34 patients were included. Eight patients (24%) had pathological level VI lymph node metastasis. The rate of pathological level VI lymph node metastasis was directly proportional to the clinical N status (P = .0002, Chi-square test for trend). In all, 5 patients with cN2b- 3 were classified as cN3b. Ipsilateral pathological level VI lymph node metastasis was observed in 1 patient, and bilateral metastasis was observed in 3 patients. There was no association between clinical T status or pyriform sinus apex invasion and pathological level VI metastasis (both P > .99, Fisher's exact test). Conclusions: PSSCC with cN3b is prone to bilateral level VI metastasis. We recommend that patients with PSSCC with cN3b should undergo bilateral level VI lymph node dissection.