Inclusion Criteria:

1. Histologically confirmed colorectal cancer

2. ≥ 18 years old

3. Measurable disease, defined as to RECIST criteria

4. Unresectable metastatic disease OR First recurrence/metastasis after adjuvant therapy
and not suitable for operation

5. FOLFIRI±cetuximab/bevacizumab as the first-line therapy

6. Without expected course of radiotherapy during the first-line chemotherapy

7. No previous CPT-11 chemotherapy

8. ECOG performance status (PS) 0-2

9. Not pregnant or nursing and Negative pregnancy test

10. Voluntarily signed the informed consent

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

12. AST and ALT ≤ 2.5 times ULN (≤ 5 times ULN if f liver metastases present)

13. Creatinine clearance > 50 mL/min OR serum creatinine ≤ 1.5 times ULN

Exclusion Criteria:

1. Brain metastases with obvious symptoms

2. Severe bone marrow failure and can not be corrected

3. Chronic diarrhea history

4. Bowel obstruction without control

5. Mental illness without control

6. Clinically significant (i.e., active) cardiovascular disease, including any of the
following: Cerebrovascular accidents/ Myocardial infarction/ Unstable angina/ New
York Heart Association class II-IV congestive heart failure/ Serious cardiac
arrhythmia requiring medication/ Uncontrolled hypertension

7. Other co-existing malignancy or malignancy diagnosed within the past 5 years, except
for basal cell or squamous cell carcinoma, or carcinoma in situ of the cervix

8. Pelvic radiotherapy for the past 1 year

9. Known allergy to any of the components of the study medications

10. Serious, nonhealing wound or ulcer