[The effect of cervical lymph node metastasis density on prognosis of hypopharyngeal carcinoma]

Objective: To investigate the relationship between the cervical lymph node density (LND) and the prognosis of hypopharyngeal carcinoma. Methods: The clinical and pathological data of 241 patients with hypopharyngeal carcinoma who underwent surgery in Shandong Provincial ENT Hospital from January 2014 to December 2017 were retrospectively analyzed, including 229 males and 12 females, aged 37-81 years. The LND was calculated, i.e. the ratio of the number of lymph nodes with metastasis to the total number of lymph nodes removed. The patients were divided into low LND group and high LND group based on the cutoff value of LND determined by receiver operating characteristic curve (ROC curve). The univariate and multivariate analyses of the disease-free survival (DFS) and the overall survival (OS) were performed in two groups. Results: With the cutoff value of 0.068, 165 patients were in the low LND group (<0.068) and 76 patients in the high LND group (≥0.068). T stage, N stage, maximum lymph node diameter, extracellular invasion of lymph node, and postpharyngeal lymph node metastasis were associated with LND (statistical values were -3.15, -6.82, 23.37, 20.44, and 30.18, respectively, all P values were<0.05). The univariate analysis showed that age, T stage, N stage, maximum diameter of cervical lymph nodes, extracapsular invasion, retropharyngeal lymph node metastasis and LND were the main factors affecting the patients' DFS (χ²=9.31, 7.30, 20.09, 15.30, 9.04, 19.44, 50.27, all P values<0.05) and OS (χ² were 5.02, 12.94, 18.28, 15.91, 7.95, 16.88, 49.45, all P values<0.05). Multivariate analysis showed that patients with age≤60 years old and LND≥0.068 had reduced DFS [HR values were 0.61 (95%CI 0.43-0.88) and 2.23 (95%CI 1.44-3.45), both P values<0.05]; patients with advanced T stage and LND≥0.068 had reduced OS [HR values were 1.73 (95%CI 1.02-2.93) and 2.39 (95%CI 1.51-3.80), both P values<0.05]. Conclusion: LND is a prognostic factor for patients with hypopharyngeal carcinoma after surgery, with worse prognosis in patients with LND≥0.068.