3.

Endoscopic treatment strategy

Stage	Stratification	Class I recommendation	Class II recommendation	Class III recommendation
EMR, endoscopic mucosal resection; ESD, endoscopic submucosal dissection. a, It is recommended that pathological testing of all non-pedunculated polyps or polyps that are suspected to be cancerous be conducted before determining whether endoscopic removal should be performed. b, The risk of cancer accompanied by regional lymph node metastases at the T1 stage is approximately 15%. Local endoscopic excision cannot determine the status of lymph nodes. After endoscopic removal of T1 (SM) cancers, not only should local colonoscopy examination be carried out, but testing of the tumor marker, carcinoembryonic antigen (CEA), abdominal ultrasound, and abdominal CT should also be conducted simultaneously (1). c, The histological criteria for confirming curative endoscopic resection of T1 colorectal cancer tissues are as follows: 1) Lesions with submucosal invasion <1 mm; 2) Absence of lymphovascular invasion; 3) Well-differentiated tumors; 4) Absence of tumor budding; and 5) Distance of tumor from resection margin ≥1 mm ( 2,3). d, When it is impossible to determine whether resection margins are negative or positive, it is recommended that follow-up endoscopy be performed in 3−6 months. If resection margins are negative, follow-up can be conducted within 1 year after endoscopic treatment (4,5). e, Larger lesions may require piecemeal endoscopic mucosal resection (PEMR). However, the local recurrence rate is high with PEMR and requires increased monitoring (6).
Adenomas and T1N0 colon adenocarcinomaa,b,c,d	Pedunculated polyps or non-pedunculated polyps with diameters of 5−20 mm	Trapectomya	EMR	—
	1. Flat lesions with diameters of 5−20 mm, 2. The wide-base lesion >10 mm was suspected to be villous adenoma or sessile serrated adenoma/polyp, 3. Suspicious high-grade intraepithelial neoplasia ≤20 mm, which is expected to be completely resected.	EMR	ESD	—
	Mucosa or submucosal adenoma >20 mm	PEMRe	ESD	—
	1. Partial T1 (SM <1 mm) colon cancer, 2. Transverse spread tumor ≥20 mm, 3. Colon polyps with fibrosis, Villous adenoma ≥25 mm.	ESD	Operation	—