OBJECTIVETo analyze the influence of the number of lymph node metastasis on survival and prophylactic postoperative radiotherapy after radical resection of thoracic esophageal carcinoma.

METHODSFour hundred and ninety-five patients with thoracic esophageal squamous cell cancer who had undergone radical resection were randomly divided into surgery group alone (S, 275) and surgery plus radiotherapy group (S + R, 220). The patients were classified into three groups: Group A: 234 patients (47.2%) without lymph node involvement; Group B: 146 patients (29.5%) with 1 to 2 involved lymph nodes and Group C: 115 patients (23.2%) with >or= 3 involved lymph nodes.

RESULTS1. The 5-year survival rate in Groups A, B and C for the same T stage (T3) was 52.6%, 28.8% and 10.9%, respectively (P = 0.0000); the 5-year survival rate in group C was 0% in S group and 19.3% in S + R group (P = 0.0336); 2. In the positive lymph node group, the metastatic rate of intra-thoracic and supraclavicular lymph node was 35.9% and 21.2% in S group and 19.7% and 4.4% in S+R group (P = 0.014 and P = 0.000). In the negative lymph node group, the metastatic rates of intra-thoracic lymph node was 27.8% in S group and 10.3% in S + R group (P = 0.003). The metastatic rate of intra-abdominal lymph node in Groups A, B and C was 3.9%, 9.4% and 17.5%, respectively (P = 0.0000). The occurrence of hematogenous metastasis was most frequent in group C (27.8%) with >or= 3 positive lymph nodes.

CONCLUSION1. The number of metastatic lymph node is one of the important factors which affects the survival of thoracic esophageal carcinoma. 2. Chemotherapy might be given to the patients with three or more lymph nodes involved who have the possibility of developing hematogenous metastasis. Postoperative radiotherapy can reduce the occurrence of intra-thoracic and supraclavicular lymph node metastasis and improve the survival of patients with three or more lymph nodes involvement.