Relationship of gross tumor volume with lymph node metastasis and prognosis of esophageal carcinoma

OBJECTIVE: To explore whether there is a relationship between gross tumor volume (GTV) and pathologic lymph node metastasis or prognosis of esophageal carcinoma, and to provide a new prognosis reference for esophageal carcinoma (EC). METHODS: Six hundred and seven patients received radical resection of thoracic esophageal carcinoma from May 2002 to June 2006 in our hospital, and their pre-operative CT images were transmitted to the three-dimensional conformal radiotherapy planning system by the network in digital format. Esophageal GTV targets were outlined and their GTV volumes were calculated. To analyze whether there is a relationship between GTV volume and pathologic lymph node metastasis or prognosis. RESULTS: In the 607 cases of esophageal carcinoma, the GTV volume was (22.5 ± 16.8) cm(3) in 374 stage N0 EC patients, significantly different from that of (30.4 ± 20.1) cm(3) in 233 stage N1 EC cases (P < 0.001). There is a significant difference between the GTV volumes of the groups with and without lymph node metastasis (P < 0.05). There was a significant difference of the GTV volumes of EC patients with one lymph node metastasis and those with ≥ 4 lymph node metastasis (P < 0.05). There was a positive correlation between GTV volume and the number of lymph node metastasis (r = 0.230, P < 0.001). The 1-, 3-, 5-year survival rates since the surgery date were 83.8%, 53.5%, and 36.4%, respectively. There was a significant difference between the survival rates of stage N0 (48.5%) and stage N1 patients (18.2%, P < 0.001), and there was a significant difference between the survival rats of patients with 0, 1 and ≥ 2 lymph node metastasis (P < 0.01). Cox regression model analysis showed that GTV volume, number of lymph node metastasis, pathological type, and lesion site were independent prognostic factors (all P < 0.05). CONCLUSION: The GTV volume of esophageal carcinoma is positively correlated with the number of pathologic lymph node metastasis, and it is an independent prognostic factor for this cancer.