The incidence and mortality of colorectal cancer in China's cancer disease spectrum is on the rise, and it is a common malignant tumor that harms the health of Chinese residents.In patients with synchronous metastatic colorectal cancer, RAS status is highly consistent in primary focus and metastasis, so NCCN guidelines recommend RAS testing of primary or metastatic tissue is feasible .However, there are also some reports that the difference of RAS status between primary and metastatic lesions was up to 22%.In additiont,there are few studies on whether the gene profile of the metastatic lesion is the same as that of the primary lesion in patients with postoperative heterogeneous metastasis in patients with stage III colorectal cancer.

The incidence and mortality of colorectal cancer in China's cancer disease spectrum is on the rise, and it is a common malignant tumor that harms the health of Chinese residents. Now NCCN guidelines recommend targeted drugs for the treatment of metastatic colorectal cancer mainly including cetuximab and panizumab whic targeting EGFR , as well as the bevacizumab and arber regofini, etc which targeing anti-angiogenic.Cetuximab and panizumab are only effective in patients with RAS wild type.

Previous studies have shown that In patients with synchronous metastatic colorectal cancer, RAS status is highly consistent in primary focus and metastasis, so NCCN guidelines recommend RAS testing of primary or metastatic tissue is feasible .However, there are also some reports that the difference of RAS status between primary and metastatic lesions was up to 22%.In additiont,there are few studies on whether the gene profile of the metastatic lesion is the same as that of the primary lesion in patients with postoperative heterogeneous metastasis in patients with stage III colorectal cancer.

Therefore, it has important clinical significance to compare the difference of gene profile between metastatic lesion and primary lesion in patients with postoperative metastasis of stage III colorectal cancer.

Inclusion Criteria:

1. Age ≥ 18 years old and ≤ 75 years old, both men and women;
2. Patients must have histologically confirmed metastatic colorectal adenocarcinoma and metastases can be punctured by interventional evaluation;
3. ECOG: 0 to 2;
4. Expected survival ≥ 12 weeks;
5. Absolute neutrophil count (ANC) ≥ 1.5 × 109 /L; Hemoglobin ≥ 8g / dL; Platelets ≥100×109/L;(According to the normal value of the clinical trial center)
6. Prothrombin time (PT) < 1.5 times the upper normal limit and thrombin time (APTT) < 1.5 times the upper normal limit;
7. Informed consent has been signed.

Exclusion Criteria:

1. Patients had surgery within three weeks will be excluded.
2. Patients have known or suspected brain metastases will be excluded.
3. Pregnant or nursing women will be excluded.
4. Patients with severe uncontrolled systemic disease, such as severe active infection, will be excluded.
5. Patients had other malignancies in the past 5 years will be excluded, except cervical carcinoma in situ or basal cell carcinoma of the skin.
6. Patients who were unable to complete the study or sign valid informed consent for medical, social or psychological reasons, which will be determined by researcher, will be excluded.
7. Organ transplant recipients who need immunosuppressive therapy will be excluded.
8. People have been known to be infected with immunodeficiency virus (HIV) or have been known to be serologically positive for HIV will be excluded.

Patients with postoperative heterochronous metastasis,who has histologically confirmed metastatic colorectal adenocarcinoma and metastases could be punctured by interventional evaluation.In addittion,patients' blood ctDNA and tissues can be used to detect genetic mutations.