To Identify KRAS Gene and Safe Margin in Association With Outcome in Colorectal Liver Metastases Following Ultrasound-guided Radiofrequency Ablation

Inclusion Criteria:

1. Diagnosed as liver metastasis of colorectal cancer;
2. There are no more than 3 liver metastases and all the lesions are not more than 5 cm; or no more than 6 liver metastases and all the lesions are not more than 3.0 cm;
3. The primary lesion of colorectal cancer has been treated curatively or is planned to undergo curative treatment;
4. KRAS gene test results can be obtained for primary or metastatic foci;
5. Signing informed consent voluntarily;
6. Men or women who have reached the age of 18;
7. Ultrasound or ultrasound contrast can clearly show the lesion and guide RFA treatment;
8. Platelet count\> 50,000/mm3, prothrombin activity\> 50%;
9. Child-Pugh grade A or B of liver disease, but no hepatic encephalopathy or/and ascites;
10. Subjects are willing to return to the research center for research follow-up;
11. Life expectancy ≥ 6 months-

Exclusion Criteria:

1. suffer from but not limited to the following serious diseases: congestive heart failure, myocardial infarction or cerebrovascular accident, or life-threatening arrhythmia in the past 6 months;
2. During pregnancy or lactation. Before receiving research treatment, women of childbearing age must have a negative serum pregnancy test;
3. Any known allergic reactions to the intravenous imaging agent used in this study;
4. There is portal vein or hepatic vein tumor infiltration/carcinoma;
5. International normalized ratio of prothrombin\> 1.5 times the upper limit of normal value (UNL) of the research center;
6. Platelet count \<50,000/mm3, absolute neutrophil count \<1500/mm3, or heme value \<10.0g/dL;
7. Serum creatinine ≥2.5mg/dL or calculated creatinine clearance (CrCl) ≤25.0ml/min;
8. Serum bilirubin\>3.0mg/dL;
9. Serum albumin \<2.8g/dL;
10. Body temperature \>101°F (38.3°C) immediately before study treatment;
11. being treated with other research drugs;
12. Heart failure NYHA function grade is III or IV .