Determine CTV of Prophylactic Radiotherapy for Thoracic Esophageal Carcinoma after Radical Surgery

ObjectiveTo study the mediastinum field CTV of postoperative prophylactic radiotherapy for thoracic esophageal carcinoma．MethodsNinety-four patients with thoracic esophageal carcinoma who had undergone radical esophagectomy with a left thoracoabdominal approach had relapsed in the mediastinum lymph node．The detailed range of recurrence mediastium lymph node in the computed-tomography was measured according to American thoracic association lymph node mapping. Results The most recurrence probability regions were region 4 and region 2． The probability was 67%（63/94）and 51%（48/94）respectively.The biggest distances between the relapse lymph node farthest border and the body middle line (including left and right boundary), the anterior of the thoracic vertebra (anterior boundary) were as follow region 2：2.53 cm （95%CI 2.45～2.62），2.39 cm （95%CI 2.22～2.56），2.71 cm （95%CI 2.64～2.78）；region 4：2.40 cm （95%CI 1.31～3.47），1.78 cm （95%CI 1.65～1.91），3.25 cm（95%CI 3.15～3.35）；region 7：2.13 cm （95%CI 2.03～2.23），2.23 cm（95%CI 2.10～2.35），3.87 cm ( 95%CI 3.78～3.97）；region 8:2.43 (95%CI1.90～2.95) ，2.20 (95%CI 2.08～2.28) ， 1.73 (95%CI 1.63～1.84)；region 3P：2.06 cm (95%CI 1.63～2.48)，1.83 cm （95%CI 1.67～1.98）, 1.64 cm（95%CI 1.55～1.72）; region 5 The biggest distances between the relapse lymph node farthest border and the body middle line 2.94 cm (95%CI 2.89～3.00),the anterior of the thoracic vertebra 3.84 cm（95%CI 3.79～3.89）. Conclusion If the recurrent mediastinum lymph nodes are supposed as GTV，the CTV of postoperative prophylactic radiotherapy should be enlarged 1 cm based on GTV.Then postoperative prophylactic radiotherapy for thoracic esophageal carcinoma which should include region 2, region 4, region 7, region 8 and region 3P and the left boundary to the body center line should be 3.5，3.4，3.1，3.4，3.1 cm ，respectively; the right boundary to the body center line should be 3.4，2.8，3.2，3.2，2.8 cm，respectively;the front boundary to anterior of vertebra should be 3.7，4.3，4.9，2.7，2.6 cm， respectively；region 5 of the left boundary to the body center line should be 3.9 cm，and the front boundary to anterior of vertebra should be 4.8 cm.The back boundary to anterior of vertebra of all the regions should be 1 cm.