This trial aims to evaluate the efficacy, safety of high-dose FOLFIRI regimen in advanced colorectal cancer patients with wild-type UGT1A1*6 and *28.

Pharmacogenetic testing of uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) *6/*28 is recommended in clinical practice prior to the administration of irinotecan (CPT-11)-based regimens, such as FOLFIRI regimen in patients with advanced colorectal cancer. To avoid severe toxicity of irinotecan, such as severe neutropenia and diarrhea, patients with UGT1A1 *6/*28 mutation often start with a reduced dose of irinotecan. However, it remains unclear whether high-dose CPT-based regimen (FOLFIRI) could increase clinical efficacy in CRC patients when compared with standard-dose FOLFIRI or FOLFOX-6 regimens. This trial aims to compare the efficacy, safety of high-dose FOLFIRI and standard-dose FOLFIRI or FOLFOX-6 in advanced colorectal cancer patients with UGT1A1*6 G/G and *28 TA6/6.

Inclusion Criteria:

• Patients should be histologically diagnosed with advanced colorectal adenocarcinoma or postoperative recurrence
• Patients should be with UGT1A1*28 wild-type TA6/6 and UGT1A1*6 wild-type G/G
• Patients have measurable lesions
• Patients are not available for targeted therapy or patients refuse to receive targeted therapy
• Age should be more than 18 years
• Performance status should be 0-2
• Hemoglobin should be more than 9.0 g/dL; Absolute Neutrophil Count should be more than 1,500/mm3; Platelet should be more than 80,000/mm3；Total Bilirubin should be less than 1.5 times of the upper limit of normal value; Alanine aminotransferase and Glutamic-oxaloacetic transaminase should less than 2.5 times of the upper limit of normal value (it can be 5 times if liver metastasis); Creatinine should be be less than 1.5 times of the upper limit of normal value

Exclusion Criteria:

• Patients with UGT1A1*28 wild-type TA6/7, TA7/7 and UGT1A1*6 wild-type G/A,A/A;
• Patients with brain metastases;
• Patients could not tolerate chemotherapy;
• Patients have secondary primary tumor;