RESUMEN
BACKGROUND & OBJECTIVE: The intensity of lymphatic metastasis consists of lymph node metastasis number (LMN) and lymph node metastasis ratio (LMR). LMR is the ratio of positive nodes to dissected nodes. LMN and LMR are 2 important prognostic factors of esophageal cancer, and are adopted in tumor staging. This study was to assess the lymphatic metastasis intensity of thoracic esophageal squamous cell carcinoma (ESCC), and explore the influential factors and lymphadenectomy pattern. METHODS: A total of 120 patients with ESCC had been operated in the Second Affiliated Hospital of Sun Yat-sen University from 1998 to 2000. The lymph nodes were dissected according to the mapping scheme of the American Thoracic Society (ATS) modified by Casson et al. RESULTS: A total of 2 631 lymph nodes were dissected with an average of 22 lymph nodes in each case. The cervical LMR was significantly higher in the upper thoracic ESCC than in the middle and lower thoracic ESCC (20.9% vs. 12.9% and 6.8%, P<0.05). The left gastric LMR was significantly higher in the lower thoracic ESCC than in the middle and upper thoracic ESCC (37.5% vs. 17.5% and 7.1%, P<0.05). Subcarinal metastatic lymph nodes were often found in the middle thoracic ESCC. T stage, histological differentiation, and circum wall involvement degree were correlated to lymphatic metastasis intensity (P<0.05); the length of esophageal lesion had no correlation to lymphatic metastasis intensity (P>0.05). The survival time of the patients received the right thoracic esophagectomy with 3-field lymphadenectomy (3-FL) was significantly longer than that of the patients received the left thoracic esophagectomy with 2-FL (P<0.05). CONCLUSIONS: During the operation on ESCC, the regions with high lymphatic metastasis intensity should be dissected. T stage, histological differentiation, and circum wall involvement degree are important influential factors of lymphatic metastasis intensity. The right thoracic esophagectomy with 3-FL is superior to the left thoracic esophagectomy with 2-FL.