Inclusion Criteria:

1. Diagnosis of Adenocarcinoma of the colon or rectum

2. Age:18-80 years old

3. Received curative resection when diagnosed as colorectal cancer, postoperative stage:
IIIC OR IV(R0 resected)

4. Adjuvant chemotherapy with mFOLFOX6 or XELOX for more than four months 5.15 days
prior recruit, meet the following criteria:

- Hematopoietic

- Absolute neutrophil count ≥ 1,500/mm^3

- Platelet count ≥ 100,000/mm^3

- Hepatic

- Total bilirubin ≤ 1.5 times upper limit of normal (ULN)

- Alkaline phosphatase ≤ 2 times ULN

- Aspartate transaminase ≤ 2.5 times ULN

- Alanine transaminase ≤ 2.5 times ULN

- No hepatic disease that would preclude study treatment or follow-up

- No uncontrolled coagulopathy

- Renal

- Creatinine clearance > 50 mL/min

- No renal disease that would preclude study treatment or follow-up

6.The ECOG scores: 0～1

Exclusion Criteria:

1. Other colorectal cancers (i.e.sarcoma,lymphoma,carcinoid,squamous cell carcinoma,or
cloacogenic carcinoma)

2. Synchronous cancer of other site

3. Hypersensitivity to capecitabine

4. No More than 4 weeks since prior participation in any investigational drug study

5. Clear indication of involvement of the pelvic side walls by imaging With distant
metastasis

6. History of invasive rectal malignancy, regardless of disease-free interval Fertile
patients must use effective contraception

7. Uncontrolled hypertension

8. Cardiovascular disease that would preclude study treatment or follow-up

9. Lack of upper gastrointestinal tract integrity or malabsorption syndrome，active upper
gastrointestinal tract bleeding

10. Pregnant or nursing, Fertile patients do not use effective contraception

11. Other malignancy within the past 5 years except effectively treated squamous cell or
basal cell skin cancer, melanoma in situ, carcinoma in situ of the cervix, or
carcinoma in situ of the colon or rectum

12. No psychiatric or addictive disorders, or other conditions that, in the opinion of
the investigator, would preclude study participation