Inclusion Criteria:  Age of 20-70 years with an ECOG ≤ 2 Age of 71-75 years with an ECOG = 0 Pathologically confirmed high-risk stage III colon adenocarcinoma (pT4N1 or pTanyN2) Curative radical resection (successful R0 resection) within 60 days before randomization  Adequate organ functions  ANC ≥ 2×106 cells/mL Hemoglobin ≥ 9.0 g/dL Platelets ≥ 100×106 cells/mL Alanine aminotransferase/aspartate aminotransferase ≤2.5 × times the upper limit of normal (ULN) Serum total bilirubin ≤ 1.5 ULN Alkaline phosphatase ≤ 2.5 × ULN Serum creatinine ≤1.5 × ULN or creatinine clearance > 50 mL/min (Cockcroft-Gault formula) Able to understand and willing to sign and date written voluntary informed consent form Life expectancy ≥ 5 years  Exclusion Criteria:  Distant metastasis Middle or lower rectal cancer of need for radiotherapy Postoperative complication of 3 or more grades of Clavien-Dindo classification Underlying disease or postoperative condition which is contraindication for chemotherapy Known hypersensitivity reaction to any study treatment component Familial adenomatosis polyposis or hereditary non-polyposis colorectal cancer Inflammatory bowel disease Previous other malignancy which cannot be curatively treated Pregnancy or breast feeding Any other situation would exclude the patient from study based on the investigator's opinion