Objective: To discuss the influence of the number of lymph nodes retrieved after selective neck dissection on the prognosis of hypopharyngeal squamous carcinoma.
Methods: A retrospective review was performed on 96 patients with hypopharyngeal squamous carcinoma between January 1995 and December 2009, and all cases were accepted initial treatment for selective neck dissection. t test was used for analysis of normally distributed and Mann-Whitney U test for non-normally distributed continuous data in two groups. Comparisons were made by χ(2) analysis for categorical variables. Overall survival, disease-free survival and neck-control rate were calculated by the Kaplan-Meier method.
Results: The mean number of lymph nodes retrieved in all patients with hypopharyngeal squamous carcinoma was 19.0 ± 11.3. Preoperative radiotherapy significantly decreased the number of retrieved lymph nodes and positive lymph nodes (t = -4.45, P < 0.001 and U = 568, P < 0.001, respectively). The number of nodes retrieved ≤ 15 was associated with 3-year overall survival of 37.7% compared with 71.3% in those with nodes retrieved > 15 by using Kaplan-Meier analysis (χ(2) = 8.214, P < 0.01). 3-year disease-free survival rates were 34.8% in those with ≤ 15 nodes and 61.7% in patients with > 15 nodes (χ(2) = 7.345, P < 0.01). The 3-year neck-control rates were 97.4% and 76.7% (> 15 nodes vs. ≤ 15 nodes;χ(2) = 5.539, P < 0.05), respectively. After adjusting for the effect of T stage and N stage on multivariate analysis, the number of nodes retrieved > 15 was an independent prognostic factor in patients undergoing selective neck dissection for hypopharyngeal squamous carcinoma (P < 0.05).
Conclusions: The number of lymph nodes retrieved is a valuable prognostic factor in patients received selective neck dissection for hypopharyngeal squamous carcinoma. These results suggest that at least 15 nodes should be examined in this setting.