Surveillance and Surgical Salvage Treatment for Endoscopically Removed T1 Colorectal Cancers.

Endoscopic submucosal dissection (ESD) enables en-bloc resection of large lesions more than 20 mm in size. Therefore, the use of ESD has gained broader acceptance for clinical applications globally. Previous reports on long-term outcomes after ESD, when followed by additional surgery, have also reported favorable results, positioning ESD as a crucial tool in providing minimally invasive treatment for T1 colorectal cancer (CRC). However, a lack of clear evidence regarding optimal surveillance strategies for T1 CRC following endoscopic treatments such as ESD remains. In some cases of T1 CRC, the need for additional surgery to address the risk of lymph node metastasis (LNM) remains a significant concern in daily practice. This narrative review aimed to examine the evidence on surveillance and additional surgery following the endoscopic treatment of T1 CRC by evaluating the criteria for intervention and associated risk factors. In cases where there are no unfavorable pathological features or risk factors for LNM, the risk of LNM is extremely low, and endoscopic techniques alone are typically sufficient in achieving curative resection for these patients. However, when risk factors for LNM are present, additional surgery should be considered. Several current guidelines recommend determining whether to pursue additional surgery or surveillance based on these risk factors, which must be carefully assessed according to individual patient conditions. Further studies are required to clarify the long-term prognosis, risk of lymph node or distant metastasis, and appropriate surveillance strategies, which may include salvage treatment such as additional surgery.