e15504 Background: The correlation between the clinical target volume (CTV) margin and esophageal squamous cell carcinoma (ESCC) recurrence pattern is not completely clear. Our aim was to retrospectively evaluate the recurrence patterns in ESCC patients who received definitive radiotherapy (RT) with different CTVs, and determine the optimum longitudinalmargin. Methods: Patients with histologically proven ESCC (N = 134) were classified into the following three groups according to the initial expanding margin of CTV at the recurrence side: CTV1 with longitudinal margin ≥ 3cm (N = 73), CTV2 with 2-3cm (N = 37), and CTV3 with < 2cm (N = 24). The recurrence patterns were analyzed relative to the CTV margins, as well as the radiation dose, tumor stage, comorbidities etc. Results: The recurrence sites were significantly different between the CTV1 and CTV3 (p < 0.001), but not between the CTV1 and CTV2 groups (p = 0.052). In addition, 42 (91.3%) of the 46 patients that received low-dose (55-60Gy) RT showed recurrence at the site of the primary tumor, an obviously greater proportion compared to those who underwent a high-dose ( > 60Gy) treatment (77.3%, p = 0.018). Drinking was also a clear contributing factor (p = 0.025). Age, smoking, comorbidities,tumor location, stage and treatment mode were not significant prognostic factors for ESCC recurrence. Conclusions: CTV with a 2-3cm longitudinal expansion to the gross tumor volume (GTV) is acceptable for radical RT for ESCC, and recurrence at the primary tumor site is associated with low radiation dose ( < 60Gy).
An atlas for clinical target volume definition, including elective nodal irradiation in definitive radiotherapy of biliary cancer
