The basic principle of tumor radiofrequency ablation therapy is that tumor cells are less tolerant to heat than normal cells, and the high-frequency radiofrequency wave generated by the radiofrequency generator sends out radiofrequency current through electrodes inserted into tumor tissues, and then forms a circuit through auxiliary electrodes, which generates heat through the friction of molecules and the escape of ions in the surrounding tissues, and the local temperature can reach 90-100℃, leading to coagulation necrosis of the tumor tissues. The mechanisms of radiofrequency ablation for tumor treatment include: ① high temperature makes the tumor tissues in the target area undergo coagulative necrosis and kills the tumor cells directly; ② high temperature affects the phase transition and fluidity of the plasma membrane of the tumor cells, thus affecting the functions of the cell membrane; ③ high temperature increases the activity of lysosomal enzymes in the tumor cells, which affects the normal functions of many kinds of cellular organelles, especially mitochondria; ④ high temperature causes the vascular tissues around the tumors to coagulate and form reaction zones, thus reducing or blocking the tumor; and ④ high temperature makes the vascular tissues around the tumors coagulate and form reaction zones. ⑤ In the process of coagulative necrosis of tumor cells, the exposure of antigen in the cell membrane and other parts or the change of immune phenotype of tumor cells can stimulate the body to produce specific antibody, which can kill or inhibit the growth or spread of the tumor, i.e., the so-called “endogenous tumor seedling” effect; ⑥ Lead to apoptosis of tumor cells. (vi) cause tumor cells to undergo apoptosis. Indications The patients who receive tumor radiofrequency ablation treatment should meet the following conditions: 1. Malignant tumors with clear pathology, histology and cytology. 2. 2. Sign the informed consent for tumor radiofrequency ablation treatment. 3.Hepatic function Child-PughA or B grade, or ChildC grade by preparation to B grade. 4.No serious organ dysfunction such as liver, kidney, heart, lung, brain, etc., and normal or near normal coagulation function. The prothrombin time is not more than 50% of the normal control, and the platelet is more than 50×109/L. 5, single tumor with diameter ≤5cm or multiple nodules with maximum diameter ≤3cm within 3 nodules without vascular or bile duct invasion or distant metastasis; small hepatocellular carcinoma unwilling to undergo surgical treatment or with contraindications to surgery; deep-centered small hepatocellular carcinoma, recurrence after surgical resection or residual small nodules. 6.Palliative treatment for middle and advanced liver cancer that cannot be surgically resected due to various reasons. 7.Patients waiting for liver transplantation before controlling tumor growth and recurrence of metastasis after transplantation. 8, Supplementary treatment for large hepatocellular carcinoma after chemotherapy via transhepatic artery cannula embolization. 9, Adjuvant treatment before and after chemotherapy for liver metastatic tumor. 10.Palliative treatment for lung malignant tumors. 11, There have been studies reporting the use of radiofrequency ablation therapy technology for malignant tumors such as renal tumors, breast tumors, and skeletal tumors, but there is a lack of sufficient evidence-based medicine to support it. In addition, due to the limitations of local treatment, radiofrequency ablation is not recommended for lesions >5 cm according to the current level of technology. The distance of the tumor from the common hepatic duct, left and right hepatic ducts in the porta hepatis should be at least 5 mm, and for multiple foci or larger tumors, according to the condition of the patient’s liver function, pre-treatment hepatic artery chemoembolization (TACE or TAE) combined with radiofrequency ablation is obviously better than simple radiofrequency ablation; for tumors located in the surface of the liver, the neighboring region of the heart diaphragm, gastrointestinal tract, open or laparoscopic treatment can be chosen, and radiofrequency ablation combined with alcohol injection is also possible. For tumors located in the liver surface, adjacent to the diaphragm and gastrointestinal tube area, open or laparoscopic treatment can be chosen, and radiofrequency ablation combined with anhydrous alcohol injection can also be used. Contraindications At present, the main contraindications include the following: 1. Tumors located in the dirty surface of the liver, in which more than 1/3 of the tumor is exposed. 2. 2.Child-PughC grade of liver function and tumor metastasis to distant organs. 3, Diffuse hepatocellular carcinoma, or combined with main to secondary branches of portal vein or hepatic vein cancerous embolism. 4, Severe jaundice, especially obstructive jaundice, or significant atrophy of the liver, the tumor is too large, and the radiofrequency ablation scope needs to reach one-third of the liver volume. 5.Recent rupture and bleeding of esophageal (fundus) varices within 1 month. 6.Severe liver, kidney, heart, lung, brain and other major organ failure. 7.Active infection, especially inflammation of the biliary system. Uncorrectable coagulation dysfunction and serious blood abnormalities, with serious bleeding tendency. 9.Intractable large amount of ascites, malignant fluid. 10.Pregnancy, consciousness disorder or patients who can not cooperate with the treatment. The implementation of radiofrequency ablation There are many ways to implement radiofrequency ablation, including percutaneous, transperitoneal laparoscopy and open abdomen, the specific use of which pathway depends on the location of the tumor, the size of the tumor and the tumor growth mode. Advantages and disadvantages of various routes: ① percutaneous route: it is most suitable for 1~3 lesions with diameter ≤3cm located around the liver, and its advantages are short hospitalization time and low complication rate; the most commonly used imaging method for percutaneous radiofrequency ablation is ultrasound, and CT is mostly used for patients with lesions close to the top of the diaphragm or those who are not clear to ultrasound investigation. Laparoscopic route: mostly used in cases where the lesion is located on the surface of the liver or cannot be detected by ultrasound. This route can accurately detect and treat liver lesions, and can detect extra-hepatic metastases in the abdominal cavity, and can also safely treat intrahepatic lesions in the neighboring peripheral organs, and hand-assisted laparoscopy can temporarily block intrahepatic vascular blood flow, reducing the thermal attenuation effect caused by blood flow and increasing the ablation effect. Radiofrequency ablation under open abdomen: radiofrequency under open abdomen is suitable for patients with large tumor foci (>5cm), more foci, foci adjacent to gastrointestinal, renal and other peripheral organs, as well as patients who have a history of abdominal surgery and can not be carried out laparoscopically. The advantage of this route is that it can more accurately reach the tumor site, and it can eliminate the thermal attenuation effect by blocking the intra-hepatic blood flow; however, the patients suffer more pain, and the recovery is slower after the operation, which is no longer minimally invasive treatment. However, patients suffer more pain and have slower postoperative recovery.