Circulating Tumor DNA Methylation Guided Postoperative Adjuvant Chemotherapy for High-risk Stage II/III Colorectal Cancer

mFOLFIRINOX (oxaliplatin 85 mg/m2, irinotecan 180 mg/m2, and folinic acid 400 mg/m2 followed by 5-fluorouracil 2400mg/m2 as a 46-hour continuous infusion on day 1) for 6 cycles

mFOLFOX6 (oxaliplatin 85 mg/m2, and folinic acid 400 mg/m2 followed by 5-fluorouracil 400mg/m2 infusion, and 2400mg/m2 as a 46-hour continuous infusion on day 1) for 12 cycles or XELOX (oxaliplatin 130mg/m2, ivgtt, Q3w; capecitabine 1000mg/m2, p.o, Q3w) for 8 cycles