The basic principle of tumor radiofrequency ablation therapy is that tumor cells are less tolerant to heat than normal cells. The high frequency radiofrequency wave generated by the radiofrequency generator sends radiofrequency current through the electrode inserted into the tumor tissue, and then forms a circuit through the auxiliary electrode, which generates heat through the molecular friction and ion escape in the surrounding tissues, resulting in coagulative necrosis of tumor tissue at a local temperature of 90-100℃. The mechanism of radiofrequency ablation for tumor treatment includes: 1) high temperature causes coagulative necrosis of tumor tissues in the target area and directly kills tumor cells; 2) high temperature affects the phase change and fluidity of tumor cell plasma membrane, thus affecting various functions of cell membrane; 3) high temperature increases the activity of lysosomal enzymes in tumor cells and affects the normal functions of various cell organelles, especially mitochondria; 4) high temperature causes coagulation of vascular tissues around the tumor and forms a reaction zone. (5) In the process of coagulation necrosis of tumor cells, the exposure of antigen in cell membrane and other parts or the change of immune phenotype of tumor cells can stimulate the body to produce specific antibodies to kill or inhibit the growth or spread of tumor, which is called “endogenous tumor seedling”; (6) It leads to apoptosis of tumor cells. It can stimulate the body to produce specific antibodies to kill or inhibit the growth or spread of tumor, which is called “endogenous tumor vaccine”. 1. Patients who receive radiofrequency tumor ablation therapy must meet the following conditions: 1. Patients with clear pathological or clinical diagnosis of liver malignant tumors: single tumor ≤ 5 cm in diameter or multiple tumors ≤ 3 in number, the largest foci ≤ 3 cm in diameter, without vascular or bile duct invasion or distant metastasis; small hepatocellular carcinoma that is unwilling to receive surgical treatment or has contraindications to surgery; small hepatocellular carcinoma of deep central type, recurrence or residual small nodules after surgical resection. residual small nodules. 2.Child-Pugh A or B grade of liver function, or Child C grade with preparation to B grade. 3.No serious liver, kidney, heart, lung, brain or other organ dysfunction, normal or near normal coagulation function. The prothrombin time does not exceed 50% of the normal control, and platelets are greater than 50×109/L. 4.Palliative treatment for intermediate to advanced hepatocellular carcinoma that cannot be surgically removed for various reasons. 5.Patients waiting for tumor growth control before liver transplantation and recurrence of metastasis after transplantation. 6.Supplementary treatment for large hepatocellular carcinoma after embolization chemotherapy via hepatic artery cannula. 7.Adjuvant treatment before and after chemotherapy for metastatic tumors of the liver. 8.Palliative treatment of lung malignant tumor. 9.There are studies reporting the use of radiofrequency ablation therapy technology for malignant tumors such as renal tumors, breast tumors, bone tumors and pancreatic tumors, but there is a lack of sufficient evidence-based medicine to support it. Due to the limitations of local treatment, radiofrequency ablation alone is not recommended for lesions >5 cm according to the current technology. For multiple lesions or larger tumors, pre-treatment hepatic artery chemoembolization (TACE or TAE) combined with radiofrequency ablation is significantly better than radiofrequency ablation alone, depending on the patient’s liver function; for tumors located on the liver surface, adjacent to the heart and diaphragm, and the gastrointestinal canal, open or laparoscopic treatment can be chosen, or radiofrequency ablation combined with anhydrous alcohol injection can be used. In addition, TACE or other treatments after RF ablation may also improve the efficacy. The main contraindications include the following: 1. Tumors located on the liver surface, more than 1/3 of which are exposed. 2. 2.Child-Pugh grade C liver function. 3.Diffuse hepatocellular carcinoma, or combined with portal trunk to secondary branches or hepatic vein carcinoma thrombosis. 4.Severe jaundice, especially obstructive jaundice, or significant atrophy of the liver, tumor is too large and the scope of radiofrequency ablation needs to reach one-third of the liver volume. 5.Ruptured esophageal (fundus) varices bleeding in the recent 1 month. 6.Severe liver, kidney, heart, lung, brain and other major organ failure. 7, Active infection especially inflammation of the biliary system, etc. 8.Incorrectable coagulation dysfunction and serious blood abnormalities, and those with serious bleeding tendency. Radiofrequency ablation has various ways of implementation, mainly including percutaneous, trans-laparoscopic and open abdomen. The advantages and disadvantages of each route are as follows: (1) percutaneous route: it is most suitable for 1 to 3 lesions with diameter ≤3 cm located around the liver, and has the advantages of short hospital stay and low complication rate; the most common imaging localization method for percutaneous RF ablation is ultrasound, and CT is mostly used for patients whose lesions are close to the top of the diaphragm or cannot be detected by ultrasound. ②Laparoscopic route: mostly used when the lesion is located on the surface of the liver or not detectable by ultrasound. This route can accurately detect and treat liver lesions, and can detect extrahepatic metastases in the abdominal cavity, and can also safely treat intrahepatic lesions in the adjacent surrounding organs, and the ablation effect can be increased by temporarily blocking the blood flow of intrahepatic vessels and reducing the thermal attenuation effect caused by blood flow under hand-assisted laparoscopy. Radiofrequency ablation under open abdomen: radiofrequency under open abdomen is suitable for patients with larger tumors (>5cm), more lesions, lesions adjacent to peripheral organs such as stomach, intestines and kidneys, and patients who have a history of abdominal surgery and cannot be performed under laparoscopy. Operation procedure Pre-operative examination and preparation: detailed medical history, careful reading of pre-operative CT and MRI films, strict compliance with the operation specification and treatment guideline of tumor ablation therapy, correct mastering of the indications and contraindications of tumor ablation therapy, comprehensive judgment according to the patient’s condition, selectable treatment means and the patient’s economic ability, etc., to decide the treatment plan. Before the implementation of tumor radiofrequency ablation treatment, patients and their families should be informed of the treatment purpose, treatment risks, post-treatment precautions, possible complications and preventive measures, etc., and sign the informed consent form. (1) Preoperative evaluation and laboratory examination of patients: ECOG score of 3 or less for tumor patients. Review blood routine, blood type, liver and kidney function, and complete set of blood clotting time. (2) Other preoperative examinations: mainly include monitoring vital signs such as blood pressure and pulse, receiving routine chest X-ray (to observe the presence of emphysema and pleural hypertrophy) and electrocardiogram, abdominal ultrasound and other examinations. If clinical consideration is needed to pass through the lung for radiofrequency ablation treatment of liver area near the top of the diaphragm or lung tumor, lung function should also be tested. (3) Preoperative preparation: fasting and water fasting for 6 hours before surgery. Empty the bladder before surgery. Prepare intravenous indwelling needle and open intravenous access. For highly stressed patients, take 10mg of diazepam orally 1 hour before surgery. explain the purpose of RF ablation treatment to the patient and try to choose the supine position. For patients with significant cough affecting the operation, codeine 30mg should be given 1 hour before the procedure. if anticoagulant drugs (e.g. aspirin, etc.) are used, they should be discontinued at least 72h before the RF ablation treatment. Pethidine injection 75-100mg for analgesia 30 minutes to 1 hour before surgery. (4) Items preparation: RF therapy instrument, RF therapy needle, phlebotomy kit, ice, imipramine 5mg; 5ml syringe or 10ml syringe, 18G intravenous indwelling needle, 2% lidocaine, iodine and swabs, tape, lap band, sphygmomanometer and stethoscope, sterile gloves. Prepare plasma or platelets if necessary. The operating room should have oxygen, sputum, cardiac monitoring and defibrillator, and resuscitation drugs on hand. 2.Operating method Emphasize that the operation should be guided by imaging technology to ensure the safety, accuracy and effectiveness of treatment. The scope of ablation should aim to include the paracancerous tissues above 0.5 cm in order to obtain a “safe margin” and kill the tumor completely. For infiltrating or metastatic carcinoma with unclear boundary and irregular shape, it is recommended to expand the safe peri-tumor area to 1 cm or more if the adjacent liver tissues and structural conditions permit. The operation steps are as follows: (1) Choose the supine position as much as possible. Connect the RF cable and electrode plate between the electrode and the main unit, and routinely apply the electrode film to the hairless part of bilateral thighs before the operation. Pre-operative pre-instrument energization test to ensure the normal operation of the instrument. (2) The skin should be routinely disinfected, sterile cavity towel should be laid, and local anesthesia of 2% lidocaine should reach the liver envelope. If it is estimated in advance that RF ablation may cause moderate to severe pain, it is strongly recommended to perform it under intravenous anesthesia to ensure that RF ablation is performed smoothly. (3) It must be performed under imaging guidance and monitoring, and multiple foci can be treated repeatedly; the patient’s condition should be closely observed during treatment to detect possible complications in time. (4) During the process of radiofrequency ablation, the vital signs should be monitored; generally, a treatment process takes about 8-12 minutes, and larger lesions need to be maintained for 24 minutes or even longer; the machine will automatically stop the ablation at the scheduled time; after the ablation is completed, the needle tract is ablated when the needle is removed to prevent postoperative bleeding and tumor implantation along the needle tract; whether to ablate other locations is decided according to the situation. (5) The occurrence of complications such as internal bleeding, pneumothorax and gastrointestinal perforation should be closely observed during the ablation treatment and after returning to the ward. V. Evaluation and follow-up of the efficacy of radiofrequency ablation Establish and improve the technical evaluation and follow-up system of tumor radiofrequency ablation treatment and record them according to the regulations. After the ablation treatment, the necrosis of lesions should be observed regularly, and if there is any residual lesion, remedial treatment should be actively carried out to improve the efficacy of radiofrequency ablation treatment. The standard method to evaluate the local efficacy is to determine whether the tumor is completely ablated (Complete ablation) by contrast-enhanced CT/MRI or ultrasonography about one month after radiofrequency ablation. For patients with more iodine deposits in the lesion, MRI enhancement can be used, which can avoid iodine artifacts and is more accurate than CT. A lesion with complete ablation shows no blood supply at all, i.e., no enhancement. If ablation is incomplete, remedial treatment can be given. If complete ablation cannot be obtained after 3 ablations, ablation therapy should be abandoned and other treatments should be used instead. Precautions 1. Preoperative liver function loss and significantly prolonged clotting time should be prepared with plasma, and platelet or coagulation factor should be transfused if necessary. For cirrhotic patients with coagulation disorders, a small dose of recombinant factor VIIa should be given; for patients with platelet count <50,000/mm3, PT prolongation >4 seconds and liver function loss, plasma and platelets can be transfused to correct it. 2.Patients should be trained to hold their breath several times in advance before surgery to cooperate with the operation. 3.Vital signs should be routinely monitored within 12 hours after surgery, first every 30 minutes to 1 hour, and then every 2 hours if stable. If blood pressure decreases during this period and there are signs of bleeding, consider the use of hemostatic drugs, blood transfusion (such as concentrated red blood cells, plasma or platelets), and if necessary, request surgical consultation for surgical exploration. 4.Patients with heart valve disease or those at risk of bacteremia need prophylactic antibiotics; if intraoperative trans-pulmonary treatment of liver tumor at the top of the diaphragm or lung tumor, preoperative prophylactic antibiotics and postoperative antibiotic treatment can be used. 5. Patients should not move their bodies during RF treatment, which is very important to complete the surgery and reduce complications. 6. Patients with cardiac pacemakers should be performed under close cardiac monitoring. 7., Patients are instructed to avoid heavy physical labor and strenuous physical activities, etc. for one week after the procedure. 8. Informed consent must be signed. Radiofrequency ablation treatment has the following risks: anesthesia accident such as cardiac arrest, allergic reaction, etc.; bleeding at the site of radiofrequency treatment, liver rupture, pneumothorax, shock, infectious or bloody pleural effusion; injury to nerves, kidney, adrenal gland, pancreas, etc.; injury to stomach, colon causing perforation possible; biliary fistula, biliary peritonitis, liver abscess; electrode skin burns; failure of radiofrequency ablation treatment, needle tract implantation metastasis, postoperative recurrence possible ; portal vein embolism after radiofrequency is a major cause of death, especially seen in patients with cirrhosis. And other unpredictable accidents. 9, the prevention and treatment of several common complications: (1) vagal reflex: radiofrequency heat generation on the liver peritoneum and the vagus nerve stimulation within the liver vagal reflex, can cause heart rate slowdown, arrhythmia, blood pressure drop, serious cases can lead to death. Atropine or sanguinarine can be given for prevention before surgery. If vagal reflex occurs during the operation, atropine or scopolamine can be given for treatment. (2) Injury to intra- and extra-hepatic bile ducts: Radiofrequency thermocoagulation of hepatocellular carcinoma in the first hilar region should avoid injuring the larger bile ducts, so the scope of thermocoagulation should not be too large. (3) Injury to perihepatic cavity organs: Especially when there is a history of surgery or imaging examination reveals that the tumor invades the surrounding cavity organs, radiofrequency thermocoagulation should be especially cautious to prevent serious complications such as internal or external fistula caused by injury to the cavity organs for complete thermal coagulation of the tumor. (4) Internal bleeding: For liver tumors that are close to the surface of the liver or protrude outside the liver, puncture should not be performed from the surface of the tumor, but through the tumor-free liver tissue and then into the tumor tissue. Intraoperative and postoperative hemostatic drugs need to be given, and lap band thoracoabdominal compression bandage should be given after treatment. (5) Pneumothorax: avoid penetrating into the thoracic cavity as much as possible under the guidance of B-ultrasound during the operation, pay attention to observe whether the respiration is stable after the operation, if there is respiratory distress, emergency chest X-ray should be given to clarify the diagnosis.