Delineating the extent of esophageal squamous cell carcinoma.

Lugol chromoendoscopy has been conventionally used for the detection and delineation of esophageal squamous cell carcinoma (SCC). However, the boundaries of some lesions are unclear even with Lugol chromoendoscopy, and there is a risk of residual lesions or over-excision. This study aimed to evaluate the utility of narrow-band imaging (NBI) for the delineation of esophageal SCC in endoscopic resection. Among 367 esophageal SCCs endoscopically resected between January and December 2019 at our institute, this retrospective study included consecutive lesions, which were first marked with NBI, followed by Lugol chromoendoscopy. The proportion of residual cancer, which was defined as histologically proven cancer confirmed adjacent to the scar within 1 year after endoscopic resection, was evaluated. To evaluate whether the marks added by Lugol chromoendoscopy after NBI marking were more reliable, we evaluated the presence of cancer in the iodine-unstained area outside the NBI-determined marks, i.e., the cancerous area missed by NBI. The presence of cancer in the iodine-stained areas inside the NBI-determined marks, i.e., the cancerous area missed by Lugol, was also evaluated. These were compared to assess the risk of residual cancer in endoscopic resection with NBI and Lugol chromoendoscopy. Among 304 lesions, 2 (0.7%) residual cancers were detected. The cancerous area missed by NBI and the cancerous area missed by Lugol were identified in 18 (6%) and 43 (14%) lesions, respectively (P = 0.001). NBI might be acceptable for delineating the extent of esophageal SCCs that are difficult to delineate with Lugol chromoendoscopy.