Value of the number and distribution of metastatic lymph nodes in postoperative radiotherapy for thoracic esophageal squamous cell carcinoma

Objective To analyze the relationship between the number as well as distributions of positive lymph nodes, and the clinical outcomes of postoperative radiotherapy for thoracic esophageal squamous cell carcinoma (TESCC) , And to evaluate the efficacy of postoperative radiotherapy . Methods From January 1993 to March 2007,945 patients with TESCC treated with three-field lymphadenectomy were involved in this study. All patients were with lymphoid metastasis but without distant metastasis. Among them, 590 patients received surgery alone and the other 355 received surgery plus postoperative radiotherapy. The radiotherapy were begun in the third or fourth week after operation and the median total radiation dose was 50 Gy in 25 fractions of 2 Gy, 5 fractions per week. Results The follow-up rate was 94.5%. 189 patients finished minimal follow-up of five years. The 5-year survival rates in the surgery alone group and in the postoperative radiotherapy group were 29.6% and 38.0%, respectively (χ~2 = 10.44 ,P = 0.001). In stratification analysis, compared with the surgery alone, postoperative radiotherapy could increase the 5-year survival rate of the patients with 3 to 5 (30.5% : 23.1%, χ~2 = 4.11, P = 0.043) or > 5 positive nodes (16.7% : 8.9%, χ~2= 6.87, P= 0.009) , or metastastatic node in the region of supraclavicular or upper mediastinum (45.5% : 34.9%, χ~2= 5.37, P = 0.020). In patients with positive nodes number less than 3, or with medium mediastinum or lower mediastinum lymph nodes metastasis, postoperative radiotherapy could not increase the 5-year survival rates (50.7% : 41.2%, χ~2 = 3.30, P = 0.069 ; 32.0% : 27.7% , χ~2= 2.22 , P = 0. 137) , Though could decrease lymph nodes metastasis in supraclavicular and medium-upper mediastinum (15 : 76, χ~2 = 18.10, P = 0.000; 18 : 97, χ~2= 26.81, P = 0.000). Conclusions In TESCC patients with positive lymph nodes number ≥3 or nodes in the region of supraclavicular and upper mediastinum, postoperative radiotherapy can improve the survival after three field lymphadenectomy. And the rate of metastastatic lymph nodes in the supraclavicular region or upper-medium mediastinum can also be decreased. Key words: Esophageal neoplasms/surgery;  Esophageal neoplasms/radlotherapy;  Metastatic number,lymph nodes;  Metastatic distribution,lymph nodes;  Prognosis