Table 1.

Definitions of high-risk stage II colon cancer according to international guidelines.

Guidelines	Definition
European Society for Medical Oncology [75]	pT4 stage and/or <12 lymph nodes assessed or multiple intermediate risk factors (i.e., lymphatic, perineural or vascular invasion, tumor obstruction, histological grade 3, preoperative CEA > 5 ng/mL) MSI/MMR status
American Society of Clinical Oncology [76]	extramural vascular invasion, grade 3/poorly differentiated tumors, T4 stage/perforation, obstructive tumors, mucinous tumors, examination of less than 12 lymph nodes, and tumor budding
National Comprehensive Cancer Network [79]	pT4 tumor, lymphovascular or perineural invasion, localized perforation or bowel obstruction, close, indetermined or positive margins, poorly differentiated tumor (excluding tumors that are MSI-H), or lymph node sampling <12 nodes