MRD-guided Deferred Adjuvant Therapy in Resectable Early-stage Colon Cancer

The aim of this clinical trial is to test whether minimal residual disease (MRD) status detected by circulating tumor DNA (ctDNA) could be used to guide precision therapy of post-surgery in colon cancer. The colon cancers are intended for resectable colon cancer of high-risk stage II and low-risk stage III status. The main questions it aims to answer are: 1. Whether patients with MRD negative status could benefit from deferred adjuvant therapy. 2. Whether patients with MRD positive status need intensive adjuvant therapy. The qualified participants will go through two different randomized groups according to the post-surgery 1-month MRD status. In MRD negative groups, participants will be divided into standard adjuvant therapy groups and deferred adjuvant therapy groups at 1:2 ratios. In MRD positive groups, participants will be divided into standard adjuvant therapy groups and intensive adjuvant therapy groups at 1:2 ratios. All the patients will receive MRD detection every 3 months and radiological evaluation every 6 months up to 3 years, and survival follow-up up to 5 years.