Pre-Resection Endoscopic Features in T1 Colorectal Cancer Selected for Salvage Surgery After ESD/EID: An Exploratory Comparison of SM1 and SM2–3 Invasion

Background/Objectives: Accurate assessment of submucosal invasion is important when selecting patients with early colorectal cancer for organ-preserving treatment. Endoscopic submucosal dissection (ESD) and endoscopic intermuscular dissection (EID) enable en bloc resection and detailed histopathological assessment. This study explored whether routinely recorded pre-resection endoscopic characteristics differed between SM1 and SM2–3 lesions within a selected cohort of patients who underwent salvage surgery after non-curative endoscopic resection.