Abstract: 【Abstract】Objective:To investigate the characteristics and risk factors of abdominal lymph node metastasis in thoracic esophageal squamous cell cancer.
Methods:The clinical data of 586 patients with thoracic esophageal cancer who underwent surgery via transabdominal and transthoracic approaches between June 2009 and June 2014 at the Sichuan Cancer Hospital were retrospectively analyzed. All the patients received resection of esophageal cancer and lymph node dissection, and the transabdominal right thoracic approach or cervicothoracicabdominal triple incision was selected according to the condition of patients. No.18, 19, 20 lymph nodes were dissected seperately and No.16, 17 and lesser curvature lymph nodes were separated. All the specimens of lymph nodes were detected by regular pathological examination. Measurement data with normal distribution were presented as ±s and count data were described as rate. Comparisons of rate between 2 specimens and among the multiple specimens were respectively analyzed using the chisquare test and partition of chisquared. The multivariate analysis was done using the logistic regression.
Results:The number of lymph node dissected in 586 patients was 12 524 with an average number  of 20±11 per case, and the rate of lymph node metastasis was 55.63%(326/586). The number of mediastinal lymph node dissected was 7 012 with an average number of 12±5 per case, and a rate of mediastinal lymph node metastasis was 40.96%(240/586). The number of abdominal lymph node dissected was 5 512 with an average number of 9±8 per case, and a metastasis rate was 31.74% 186/586). The abdominal lymph node metastasis rate of the upper, middle and lower thoracic esophageal cancer were 13.73%(14/102), 31.51%(92/292) and 41.67%(80/192), respectively, showing a significant difference among the above 3 indexes (χ²=25.91, P<0.05). The lymph node metastasis rate in No.16, 17, 18, 19, 20 and lesser curvature lymph nodes were 12.80%(75/586), 16.89%(99/586), 1.71%(10/586), 0.68%(4/586), 1.71%(10/586) and 2.05%(12/586), respectively, with a significant difference among the above 6 indexes (χ²=287.95, P<0.05). The results of univariate analysis showed that the tumor location, surgical procedure, T stage, N stage, G stage, pathological stage and mediastinal lymph node metastasis were risk factors affecting abdominal lymph node metastasis of thoracic esophageal cancer (χ²=24.02, 23.97, 37.87, 136.85, 38.79, 7.70, 154.27, P<0.05). The tumor in the lower thoracic portion, N3 stage and stage Ⅳ were independent risk factors affecting abdominal lymph node metastasis of thoracic esophageal cancer in the multivariate analysis (RR=5.80, 2.36, 2.76, 95% confidence interval: 1.02²-1.813, 1.317-3.950, 1.65²-12.351, P< 0.05).
Conclusions:  Abdominal lymph node metastasis is common in thoracic esophageal cancer in which No.16 and 17 lymph nodes predominate, and it is easy to occur in patients with lower thoracic esophageal cancer, and advanced N stage and pathological type.