Characteristics of the local recurrence pattern after curative resection and values in target region delineation in postoperative radiotherapy for lower thoracic esophageal squamous cell cancer

BACKGROUND The aim of this study was to investigate the patterns and influencing factors of local-regional recurrence of lower thoracic esophageal squamous cell carcinoma (TESCC) after curative resection and to delineate the clinical target volume (CTV) of postoperative radiotherapy (PORT). METHODS From January 2009 to December 2013, the clinical data of patients who experienced local-regional recurrence after curative esophagectomy were collected and analyzed to determine local-regional recurrence patterns and to evaluate whether a proposed T-shaped PORT CTV could cover regions of local-regional failure. RESULTS A total of 108 patients were eligible for this study. All patients experienced postoperative recurrence of lower TESCC. The time to local-regional failure varied from one to 52 months (average 13.4 ± 11.0). Among the 108 patients, 127 recurrence sites were detected as the first recurrence event: 37 cases in the bilateral supraclavicular region, 56 in the upper mediastinum, 14 in the middle mediastinum, 15 in the upper abdominal lymph nodes, and five cases of anastomotic recurrence. The proposed PORT CTV could successfully cover 89 (82.4%) out of the 108 recurrences and 84.2% of the sites (107/127) of recurrence in our sample. CONCLUSION Local-regional recurrence of lower TESCC is mainly distributed in the supraclavicular, upper-middle mediastinum, anastomotic stoma, and upper abdominal lymph node regions. The proposed T-shaped PORT CTV field could cover over 80% of local-regional failure in our sample; therefore, we suggest that PORT should focus on this area.