Effects of lymph nodes count on the prognosis of patients with pathologically lymph node-negative hypopharyngeal squamous cell carcinoma

Abstract

Objective To investigate the relationship between lymph nodes count after selective neck lymph node dissection and the prognosis of patients with pathologically lymph node-negative (pN0) hypopharyngeal squamous cell carcinoma (HPSCC). Methods The clinical data of 96 patients with pN0 HPSCC undergoing selective neck dissection (bilateralⅡ-Ⅳregion) from October 1995 to October 2012 in Shanxi Provincial Cancer Hospital were analyzed retrospectively. The optimal lymph nodes count cutoff values were determined by using the X-tile program in different prognostic groups, and the univariate and multivariate survival analysis in different groups were analyzed by using SPSS 19.0 software. Results A total of 2 116 lymph nodes were detected in this cohort, with a median number of 22 (3-52). Except for the tumor site (P= 0.011), there were no statistical differences in lymph nodes count of patients with different age, gender, history of smoking or drinking, T stage, and differentiation degree (all P > 0.05). Applying 9 and 23 nodes as the cutoff values determined by using X-tile program, all patients could be divided into the high-risk (13 cases, lymph nodes count 3-9), the middle-risk (37 cases, lymph nodes count 10-22) and the low-risk (46 cases, lymph nodes count 23-52) groups. And the 5-year overall survival (OS) rate was 23.1%, 55.9% and 86.0% in the high, middle, low risk groups respectively (χ 2= 21.73, P < 0.001). Multiple-factor analysis showed that lymph nodes count, T stage and degree of tumor differentiation were independent prognostic factors in patients with pN0 HPSCC (all P < 0.05). Further analysis showed that when the cutoff value of lymph nodes count was 9, the patients could be divided into two groups with significantly different prognosis. The 5-year OS rate was 23.1% in the high-risk group and 73.2% in the low-risk group, and the difference was statistically significant (χ 2= 17.87, P < 0.001). Conclusions Lymph nodes count after selective neck lymph node dissection can be used to predict the prognosis of patients with pN0 HPSCC. It is likely that 9 is the minimum number of lymph nodes in pN0 HPSCC patients. Key words: Hypopharyngeal neoplasms; Carcinoma, squamous cell; Lymphatic metastasis; Neck dissection; Prognosis