CAPEOX vs Observation in Colorectal Cancer Patients With Positive MRD

Inclusion criteria

• Colorectal cancer confirmed by pathology, and the TNM stage (AJCC v8) is stage I or stage II. Stage II patients have T3 colonic adenocarcinoma with proficient mismatch-repair system (by immunohistochemistry for four mismatch repair proteins MSH1, MSH2, MSH6, and PMS2) and have no the following clinical risk factors: a) less than 12 lymph nodes examined; b) mucinous carcinoma; c) poor differentiation; d) bowel obstruction or perforation; e) lymphatic/vascular invasion, perineural invasion; f) close, indeterminate, uncertain, positive margins
• ECOG performance status 0-1
• No neoadjuvant therapy before surgery
• Appropriate for active surveillance (i.e., no adjuvant chemotherapy) based on current practice patterns or according to the Chinese Society of Clinical Oncology guidelines for Colorectal Cancer (version 2022)
• No history of other primary cancers in the past 3 years
• No history of bone marrow, stem cell or organ transplant
• Blood samples from 7 to 21 days after surgery were tested positive for ctDNA (tested by MinerVa MRD assay)
• Pregnancy test done within 14 days before randomization must be negative (for women of childbearing potential only)
• Voluntarily join the study and sign the informed consent document
• No unstable or any medical condition that affects patient safety and study compliance evaluated by researchers
• Availability and provision of adequate surgical tumor tissue for molecular diagnostics

Exclusion criteria

• Patients with multiple primary colorectal cancers
• Patients with another primary cancer
• Patients have the following conditions by blood test, or have obvious contraindication in adjuvant chemotherapy:

• Moderate/severe renal impairment (GFR<30 ml/min), as calculated by the Cockcroft and Gault equation
• Absolute neutrophil count <1.5×109/L
• Platelet count < 75×109/L
• Hemoglobin <90 g/L
• Aspartate aminotransferase/Alanine aminotransferase >2.5 × upper limit of normal
• Lactating women
• Have serious or uncontrolled medical condition that may preclude compliance with the protocol