Metachronous squamous cell carcinoma of the esophagus arising after endoscopic mucosal resection

Background: Endoscopic mucosal resection (EMR) is being used increasingly to treat early stage esophageal carcinoma. However, the preserved esophageal mucosa may be the source of new lesions. The aims of this study were to analyze the frequency of metachronous esophageal carcinoma after EMR and to determine whether minute iodine unstained areas often associated with squamous cell carcinoma develop into carcinoma. Methods: Eighty-two patients with esophageal squamous cell carcinoma who underwent EMR were studied. Based on the iodine staining pattern at initial EMR, they were divided into those with uniform (group U) and scattered (group S) types of background mucosa. Patients were followed by endoscopy with iodine staining (group U: median 39 months, range 12 to 71 months; group S: median 38 months, range 14 to 68 months). Results: In total, 12 (14.6%) of 82 patients were found to have metachronous esophageal carcinoma during follow-up, including 6 (37.5%) of 16 patients in group S. The cumulative proportion of metachronous carcinoma-free subjects was significantly lower in group S than group U (p=0.0048). Conclusions: Primary esophageal carcinoma develops frequently in patients who have undergone EMR for esophageal squamous carcinoma. The high frequency of metachronous carcinoma may be attributed to field carcinogenesis. Careful long-term endoscopic observation is required for patients who undergo EMR for esophageal carcinoma, especially those with scattered-type iodine staining of the background mucosa.