This study enrolling patients with metastatic colorectal cancer. Detecting CTC at different points in the treatment process. Descripting the molecular atlas of CTC in mCRC patients. Building and validating a response prediction system of mCTC patients.

Inclusion Criteria:

• Age 18-80 years;

histologically proven colorectal liver metastasis

With liver-dominant disease (extrahepatic metastases limited to lung metastases)

ECOG 0-1

A life expectancy of ≥ 3 months

Adequate hematologic function: absolute neutrophil count (ANC)≥1.5×109/l, platelets≥75×109/l, and international normalized ratio (INR) ≤1.3

Adequate liver and renal function: total bilirubin ≤2.0 mg/dl, alanine aminotransferase, aspartate aminotransferase ≤ 5x upper limit of normal, and albumin≥2.5 g/dl, serum creatinine≤2.0 mg/dl

Written informed consent for participation in the trial.

Exclusion Criteria:

• Other previous malignancy within 5 years

Have metastases other than liver and lung metastases

Receiving any treatment before first blood collection

Patients with metastatic colorectal cancer (with lung or liver metastases) who receiving chemotherapy with or without target therapy