Esophageal squamous cell cancer, Neoadjuvant radiation, Target volume, Neoplasms. Tumors. Oncology. Including cancer and carcinogens, RC254-282

Abstract Background This study aimed to establish a consensus on the delineation of target volumes for neoadjuvant radiation therapy (nRT) in esophageal squamous cell carcinoma (ESCC) within China. Methods From February 2020 to June 2021, nine ESCC patients who received nRT were retrospectively selected from Sun Yat-sen University Cancer Center and Shandong Cancer Hospital. A panel from eight cancer radiotherapy centers performed two rounds of nRT target volume delineation for these patients: the first round for cases 1–6 and the second for cases 7–9. Online meetings were held after each delineation round to discuss findings. The consistency of delineations across centers was compared using mean undirected Hausdorff distances (Hmean), dice similarity coefficients (DSC), and total volumes, analyzed with the Mann-Whitney U test. Results The second round of delineations showed improved consistency across centers (total clinical target volume (CTVtotal): mean DSC = 0.76–0.81; mean Hmean = 2.11–3.14 cm) compared to the first round (CTVtotal: mean DSC = 0.63–0.64; mean Hmean = 5.66–7.34 cm; DSC and Hmean: P