BackgroundThis 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. MethodsFrom 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. ResultsThe 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 < 0.050 between rounds), leading to the formation of a consensus and an atlas for ESCC nRT target volume delineation. A proposal was reached through evaluating target volume delineations, analyzing questionnaire survey outcomes, and reviewing pertinent literature. ConclusionsWe have developed guidelines and an atlas for target volume delineation in nRT therapy for ESCC in China. These resources are designed to facilitate more consistent delineation of target volumes in both clinical practice and clinical trials.