The purpose of this study is to investigate efficacy and safety of intra-operative chemotherapy with 5-FU for colorectal cancer patients receiving curative resection. The hypothesis is intra-operative intervention might be the best timing for cancer cells killing by cytotoxic agents, when most of residual cancer cells may get a rapid growth after tumor debulking and may become more chemotherapy-sensitive. A three-step procedure is designed for intra-operative chemotherapy with 5-FU of 1500 mg/m2, including step 1 of intraluminal 5-FU injection with 1000 mg/m2 at beginning of resection, step 2 of 200mg/m2 5-FU injection into portal vein system via mesentery vein after tumor removal and finish of bowel reconstruction, and step 3 of 300mg/m2 5-FU left into the abdominal cavity before incision closure. The controlled arm receive curative resection only. All the other treatments will stick to the guidelines.

Inclusion Criteria:

• histologically confirmed as adenocarcinoma of colon and rectum
• age 18-75 years
• eligible for curative surgical resection
• performance score: ECOG 0-1
• normal blood cells counts: WBC ≥ 4.0×10*9/L，PLT ≥ 100×10*9/L
• normal blood chemistry test: ALT/AST ≤ 2.5 ULN, TBil ≤ 1.5 ULN, BUN ≤ 1.5 ULN,Cr ≤ 1.5 ULN
• normal ECG
• no history of other malignant tumors
• no concomitant anti-cancer therapy

Exclusion Criteria:

• clinical bowel obstruction
• anticipated into another clinical trial within three months
• uncontrolled infection, serious internal medical diseases
• Pregnant or lactating women
• mentally abnormal patients
• patients known allergic to 5-FU