Advanced Colon Cancer after Curative Resection of Intramucosal Adenocarcinoma with Endoscopic Submucosal Dissection

Endoscopic resection, particularly endoscopic submucosal dissection (ESD), for colorectal cancers enables a precise pathological diagnosis and safe R0 resection. The recurrence rate after ESD is generally extremely low, with annual surveillance colonoscopy recommended. However, surveillance may not be considered for super-elderly patients owing to their condition. This is a case report of an 85-year-old man in whom curative resection was achieved for an intramucosal adenocarcinoma with ESD. The patient presented with a hypoechoic mass located in his lower right abdomen, diagnosed via surveillance abdominal ultrasound. He had undergone curative ESD for intramucosal cecal cancer 2 years prior. Colonoscopy revealed a type 2 epithelial tumor at the proximal aspect of the ESD scar. Ileocolic resection with lymph node dissection was performed. An epithelial tumor and well-differentiated adenocarcinoma but not a submucosal tumor was detected in the mucosal layer. The lesion was diagnosed not as a local recurrence after ESD but as a newly emerged original advanced cancer. After ESD for colorectal cancer, a newly developed advanced cancer may occur at the site of the ESD scar in a shorter term than usual. Surveillance colonoscopy after ESD is necessary even for super-elderly patients.