Postoperative Circulating Tumor DNA Monitoring in Stage I-III Driver-Mutant Colon Adenocarcinoma

This multicenter prospective observational cohort study will enroll 392 patients with stage I-III colon adenocarcinoma who undergo curative resection and whose tumors harbor at least one prespecified oncogenic driver mutation (KRAS, NRAS, BRAF, or PIK3CA). Serial plasma circulating tumor DNA (ctDNA) testing for molecular residual disease (MRD) will be performed with a standardized 10-gene next-generation sequencing (NGS) panel at predefined time points during 3 years of postoperative follow-up. The primary objective is to evaluate the association between postoperative ctDNA-based MRD status and recurrence-free survival (RFS). Secondary objectives include evaluating overall survival (OS), the interval between first MRD detection and radiologically confirmed recurrence, and the association between longitudinal MRD changes and outcomes following adjuvant chemotherapy.

Inclusion Criteria: 1. Age 18-75 years, regardless of sex 2. Pathologically confirmed colon adenocarcinoma, clinical stage I-III without preoperative endoscopic submucosal dissection (ESD) or endoscopic mucosal resection (EMR) 3. Planned curative surgical resection, no prior anti-tumor therapy (chemotherapy, radiotherapy, targeted therapy) before surgery 4. Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1 5. Tumor tissue positive for at least one driver mutation among KRAS, NRAS, BRAF, PIK3CA 6. Voluntary participation with signed written informed consent, good compliance with scheduled follow-up and blood collection. Exclusion Criteria: 1. Received neoadjuvant chemotherapy, radiotherapy or targeted therapy before surgery 2. History of other malignant tumors (excluding non-adenomatous colorectal neoplasms) 3. Pregnant or breastfeeding women 4. Severe concurrent systemic diseases that interfere with long-term follow-up or short-term survival (uncontrolled severe infection, organ failure, mental disorders, or other serious conditions) 5. Abnormal laboratory values or social/family factors judged by investigator to impede sample collection and follow-up 6. Simultaneous participation in other interventional clinical trials with mandatory assigned postoperative treatment regimen