Raltitrexed-based Chemotherapy Plus Bevacizumab in Retreated Patients With Advanced Colorectal Cancer

Inclusion Criteria: * 18-70 years; * histological and/or cytological confirmation of ACC; * disease progression while on first-line palliative fluoropyrimidine-based chemotherapy or relapse within 6 months after adjuvant chemotherapy; * at least one measurable objective tumor lesion by spiral CT examination, the maximum diameter ≥ 1cm（according to RECIST 1.1） * ECOG performance status 0-1 * life expectancy of at least 3 months * satisfactory main organ function，laboratory test must meet the following criteria: hemoglobin (HGB) ≥90g/L, neutrophil count（ANC） ≥1.5×109/L, platelet count（PLT） ≥80×109/L, Serum creatinine（CR）≤1.5 upper normal limitation (UNL)，total bilirubin (TBil) ≤1.5 upper normal limitation (UNL), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤2.5 UNL (For patients with liver metastasis, the AST/ALT must be ≤5.0 UNL), Alkaline phosphatase（ALP）≤3 UNL(For patients with liver metastasis, the ALP must be ≤5.0 UNL); * written informed consent Exclusion Criteria: * prior exposure to raltitrexed; * Clinically significant cardiovascular disease, for example symptomatic coronary artery disease, myocardial infarction (\<=6 months before treatment start),congestive heart failure （New York Heart Association ，NYHA\>= grade 3）,stroke or transient ischemic attack * Accept kidney dialysis treatment now * chronic enteropathy on unresolved bowel obstruction; * previous malignant disease other than carcinoma in situ of the cervix or basal cell carcinoma of the skin; * the UGT1A1 \*28（7/7）\*6（A/A） gene type; * pregnant or lactated women; * Unsuitable for the study or other chemotherapy determined by investigator.