Delineation Of Clinical Target Volume For Crossing Segments Thoracic Esophageal Squamous Cell Carcinoma Based On The Pattern Of Lymph Node Metastases

AIM: to investigate lymph node metastases(LNM) pattern of crossing-segments thoracic esophageal squamous cell carcinoma(ESCC) and its significance in clinical target volume(CTV) delineation.METHODS: from January 2000 to December 2014, patients with crossing-segments thoracic ESCC were retrospectively collected who underwent surgery including esophagectomy and lymphadenectomy at Shandong Cancer Hospital and Institute. Esophagus segments were determined by 7th edition of AJCC. Tumor location was defined by the distance from tumor center and the upper incisor. Crossing-segments thoracic ESCC were defined as tumors whose centers and edges were not in the same segment of esophagus. The sites with LNM rate higher than 10%, an empirical cut-off value, were considered as high-risk areas and were included in clinical target volume of thoracic ESCC patients for radiotherapyRESULTS: 1,501 crossing-segments thoracic ESCC patients were included into the study. The rate of LNM were 12.1%, 15.2%, 8.0%, 3.0%, and 7.1% in neck, upper mediastinum, middle mediastinum, lower mediastinum, and abdominal cavity for patients with upper-middle thoracic ESCC, 10.3%, 8.2%, 11.0%, 4.8%, 8.2% for middle-upper thoracic ESCC, 4.8%, 4.8%, 24.1%, 6.3%, 22.8% for middle-lower thoracic ESCC and 3.9%, 3.1%, 22.8%, 11.9%, 25.8% for lower-middle thoracic ESCC, respectively. The top three sites of LNM were 105(12.1%), 108(6.1%), 101(6.1%) for upper-middle thoracic ESCC, 108(8.2%), 105(7.5%), 106(6.8%) for middle-upper thoracic ESCC, 1(18.8%), 108(17.9%), 107(9.6%) for middle-lower thoracic ESCC, 1(21.3%), 108(16.1%), 107(10.1%) for lower-middle thoracic ESCC.CONCLUSIONS: crossing-segments thoracic ESCC was remarkably common. When delineating their CTV, tumor location should be taken into consideration. For upper-middle ESCC, 101, 104, 105, 106, and part of 108 should be included in the CTV; for middle-upper ESCC, 101, 104, 105, 106, 107, 108, part of 110 should be incorporated; for middle-lower ESCC, CTV should cover 105, 106, 107, 108, part of 110, 1, 2, 3, 7; for lower-middle ESCC, 107, 108, 110, 1, 2, 3 and 7 should be included in CTV.