In esophageal squamous cell carcinoma (ESCC), extracapsular extention (ECE) in metastatic lymph nodes portends high rate of recurrence and poor prognosis. To our knowledge, the effectiveness of postoperative chemoradiotherapy (CRT) in these patients has never been investigated. In this retrospective study, we compared the outcomes of surgery with or without postoperative chemoradiotherapy in ESCC patients with ECE. Based on log-rank stratified by T stage, postoperative adjuvant CRT significantly improved the overall survival (p=0.017) and progression free survival (p=0.002). In multivariate analysis, adjuvant CRT was identified as an independent prognostic factor (HR=0.494, CI 0.290-0.844, p=0.010). Compared with surgery alone, the CRT group had significantly fewer cases of regional recurrence (P=0.048) and overall recurrence (P=0.024). However, there was no significant difference in distant metastasis between two groups (P=0.755). In conclusion, our data suggest that the postoperative adjuvant CRT might be beneficial in selected subgroups of ESCC patients with ECE. To further verify these results, a prospective trial with a large sample size is needed.

There is no consensus regarding the clinical target volume (CTV) margins which surround the gross tumor volume of metastatic lymph nodes (LN) in radiotherapy of esophageal squamous cell carcinoma (ESCC). This study retrospectively assessed the distance of extracapsular extension (ECE) of metastatic LN in thoracic ESCC and defined nodal CTV margins. Histological sections of metastatic LNs from 217 patients with thoracic ESCC were re-examined. The incidence and maximal distance of ECE of metastatic LNs were assessed. The relationships between ECE and clinicopathologic features were also investigated. The ECE was found in 37.3% of patients (81/217) and 23.1% of metastatic LN (159/689), and the incidences had a significant relationship with N stage and LN size. The median distance of ECE was 1.0 mm (range, 0.2-9.7 mm). The distance of ECE showed a positive correlation with LN size (Spearman's correlation coefficient = 0.419; p<0.001). The ECE distances of LN with <10 mm diameter were significantly smaller than LN with 10-30 mm diameter (p<0.001). The 95th percentiles of ECE distances for these two groups were 3 mm and 5 mm, respectively. For pathologic LN <10 mm in diameter, a 3-mm CTV margin appears to be adequate to encompass 95% of the microscopic ECE, and for LN 10-30 mm, a 5-mm CTV margin is recommended.