Local treatment Although surgery is the treatment of choice for hepatocellular carcinoma, most patients are already in the middle and late stages at the time of diagnosis and often lose the opportunity for surgery, and according to statistics, only about 20% of patients are suitable for surgery. Therefore, non-surgical treatment needs to be actively adopted, which may lead to symptom reduction, improvement in quality of life and prolongation of survival for a considerable number of patients. Wang Yuehua, Department of General Surgery, Xuanwu Hospital, Capital Medical University Local ablation therapy is a type of treatment that directly kills tumor tissues locally by physical or chemical methods with the guidance of medical imaging technology to target and locate the tumor. It mainly includes radiofrequency ablation (RFA), microwave ablation (MWA), cryoablation, high-powered focused ultrasound ablation (HIFU) and anhydrous ethanol injection (PEI), which are minimally invasive, safe, simple and easy to perform multiple times. The imaging-guided techniques include US, CT and MRI, while the treatment routes are percutaneous, trans-laparoscopic surgery and trans-open surgery. 1, indications and contraindications. (1) Indications:Usually applicable to single tumor with maximum diameter ≤5cm; or tumor number ≤3 and maximum diameter ≤3cm without vascular, bile duct and adjacent organ invasion and distant metastasis. Liver function is graded as Child-Pugh grade A or B, or the standard is achieved with medical liver care. Sometimes, for single tumors >5cm in diameter that cannot be surgically resected, or multiple tumors with a maximum diameter >3cm, local ablation can be used as part of palliative comprehensive treatment, but it needs to be strictly controlled. (2) Contraindications: ① huge tumor or diffuse hepatocellular carcinoma; ② combined portal trunk to secondary branch carcinoma thrombosis or hepatic vein carcinoma thrombosis, adjacent organ invasion or distant metastasis; ③ tumors located on the visceral surface of the liver, more than 1/3 of which are exposed externally; ④ liver function classification of Child-Pugh grade C, which cannot be improved by liver protection therapy; ⑤ ruptured esophagogastric fundic variceal bleeding within 1 month before treatment; ⑥ un (6) patients with uncorrectable coagulation dysfunction and obvious blood abnormalities with obvious bleeding tendency; (7) patients with intractable massive ascites and malignant fluid; (8) patients with combined active infection, especially inflammation of biliary system, etc.; (9) patients with important organ failure such as liver, kidney, heart, lung and brain; (10) patients with impaired consciousness or unable to cooperate with treatment. Meanwhile, tumor in the first hilar region should be a relative contraindication; tumor close to the gallbladder, gastrointestinal, diaphragm or protruding from the liver peritoneum is a relative contraindication to percutaneous puncture route; intrahepatic lesions with extrahepatic metastases should not be regarded as absolute contraindication, and sometimes local ablation therapy can still be considered to control the development of local lesions. 2.The selection and application of common ablation means. (1) Radiofrequency ablation (RFA): It is the representative treatment mode of minimally invasive treatment for hepatocellular carcinoma and the most widely used thermal ablation method; its advantages are convenient operation, avoidance of open surgery, short hospitalization time, precise curative effect and relatively low cost. For patients with small hepatocellular carcinoma, the long-term efficacy of RFA is similar to that of liver transplantation and hepatic resection, and is superior to TAE/TACE treatment alone. Compared with anhydrous ethanol injection, RFA has the significant advantages of high radical rate, less number of treatments required and high long-term survival rate for 3-5 cm tumors. The essence of RFA treatment is the precise inactivation of the tumor as a whole and minimization of normal liver tissue damage, which presupposes the confirmation of the extent of tumor infiltration and satellite foci. Therefore, precise imaging prior to treatment is highly emphasized, and ultrasound is the preferred method to guide RFA treatment. In recent years, ultrasonography (CEUS) has played an important role; CEUS helps to confirm the actual size and shape of the tumor, define the extent of tumor infiltration, detect microscopic hepatocellular carcinoma and satellite foci, and provide a reliable reference basis for developing ablation protocols to inactivate the tumor. The tumors in the peripheral areas such as cardiodiaphragmatic surface, gastrointestinal area, gallbladder and hepatic hilum are not safe enough and prone to complications; the invasion of adjacent large blood vessels or tumor rich blood supply causes heat loss (i.e. “heat sink effect”), resulting in tumor residual recurrence. For tumors >5cm, RFA is difficult to obtain radical efficacy; it is easy to miss small satellite foci, resulting in a high recurrence rate; RFA is difficult to control metastasis and there are problems such as needle tract metastasis, puncture-induced damage to surrounding organs and induced rupture of liver cancer, etc. In addition, it is not suitable for liver cancer located in image blind areas. (2) Microwave ablation (MWA): a commonly used thermal ablation method in China, which has no significant difference with RFA in terms of local efficacy, complication rate and long-term survival. Nowadays, the MWA technique can also inactivate tumors at one time. For tumors with rich blood supply, coagulation can first block the main trophoblastic vessels before inactivating the tumor, which can improve the efficacy. The establishment of temperature monitoring system can regulate the effective thermal field range to ensure the coagulation effect. (3) ercutaneous ethanolinjection (PEI): It is suitable for the treatment of small hepatocellular carcinoma and recurrent small hepatocellular carcinoma with diameter ≤3cm or less. It can also play a role of palliative treatment for liver cancer or recurrent foci above >3cm that are not suitable for surgery. Clinically, some cancer foci are close to hepatoportal, gallbladder and gastrointestinal tract tissues, and thermal ablation treatment (RFA and MWA) may easily cause damage; at this time, PEI or PEI combined with thermal ablation can be considered to prevent complications. RFA and MWA both cause local tumor cell necrosis through thermal effect, but MWA may introduce more energy and ablate a larger area, but there is no significant difference between them in terms of local efficacy, complications, and survival rate. The necrosis of lesions should be observed regularly after ablation treatment, and if there is any residual lesion, it should be treated actively to improve the efficacy of ablation treatment. 3.Basic technical requirements. (1) Special emphasis is placed on the fact that the operating physician must be strictly trained and meticulously responsible. Before treatment, the patient’s systemic condition, disease, tumor biological behavior (predicting feasibility and effect, determining treatment and combined treatment measures and steps) and imaging examination should be comprehensively and fully evaluated, and a complete treatment plan and strategy should be formulated according to the size, infiltration range and location of the tumor to ensure sufficient safety range (1) To obtain one-time, conformal and complete ablative treatment as far as possible. (2) Emphasize the selection of suitable imaging technology to guide the operation and monitor the treatment process in order to ensure the safety, accuracy and effectiveness of the treatment. (3) The distance of the tumor from the common hepatic duct and the right and left hepatic ducts should be at least 5 mm, and ablation therapy alone is not recommended for lesions >5 cm. For multiple lesions or larger tumors, the combination of pre-treatment hepatic artery chemoembolization (TACE or TAE) + radiofrequency is significantly better than radiofrequency treatment alone, depending on the patient’s liver function. (4) The scope of ablation should aim to include 5 mm of paracancerous tissues in order to obtain a “safe margin” and completely kill the tumor. For infiltrating or metastatic cancer foci with unclear boundary and irregular shape, it is recommended to expand the ablation scope as long as the adjacent liver tissues and structural conditions permit. For tumors with rich blood supply, coagulation can be considered to block the main trophoblastic blood supply before ablation to improve the inactivation effect. (5) The standardized method to evaluate the local efficacy is to review the third stage CT/MRI scan of liver or ultrasonography about 1 month after ablation and 1 month after treatment to evaluate the ablation efficacy. The efficacy of ablation can be classified as follows: ① complete response (CR): the tumor is hypointense in the area (hyperechoic on ultrasound) and no enhancement is seen in the arterial phase after follow-up by CT/MRI scan or ultrasonography; ② incomplete response (ICR): the tumor is hypointense in the area after follow-up by CT/MRI scan or ultrasonography. (2) incomplete ablation (ICR): localized enhancement in the arterial phase of the tumor lesion after three CT/MRI scans or ultrasonography follow-up, suggesting residual tumor. If there is tumor residue after treatment, ablation therapy can be carried out again; if there is still tumor residue after 2 ablations, it is regarded as ablation therapy failure, and ablation therapy should be abandoned and other therapies should be used instead. (6) There should be suitable comprehensive treatment plan and scientific and reasonable follow-up plan. After treatment, regular follow-up should be conducted to detect possible local recurrent lesions and new intrahepatic lesions in time, and to effectively control tumor progression by using the advantages of minimally invasive and simple percutaneous ablation which can be performed repeatedly. 4.The choice of ablation therapy and surgery for hepatocellular carcinoma ≤5cm. Currently, there is a clinical controversy whether surgery or percutaneous ablation should be preferred for hepatocellular carcinoma ≤5 cm. The results of several prospective randomized controlled and retrospective comparative studies have shown that local ablation therapy (mainly RFA and MWA) can achieve similar long-term survival outcomes as surgical resection for small hepatocellular carcinoma; however, compared with surgical resection, surgical resection has the advantages of accumulated experience, high prevalence and low recurrence rate, and can remove multiple lesions, microscopic foci and cancer thrombi in the same anatomical region; while percutaneous local ablation is characterized by low complication rate, rapid recovery and short hospital stay. Two randomized controlled studies have shown no significant difference in survival between ablation and surgical resection, but surgery has an advantage in terms of tumor-free survival (DFS) and recurrence rate. In clinical practice, the appropriate initial treatment should be selected after thorough consideration of the patient’s physical condition and liver function, the size, number, and location of the tumor, the technical strength of the unit, and the patient’s wishes. It is usually considered that if the patient can tolerate anatomical liver resection, surgical resection should be preferred, which can simultaneously remove micro-metastases in the corresponding liver segment or lobe and effectively prevent postoperative recurrence. Therefore, surgical treatment is still the first choice for the treatment of ≤5 cm hepatocellular carcinoma. For ≤5 cm hepatocellular carcinoma that meets the indications of both local surgical treatment and ablation treatment, surgical treatment is still performed when available, while local ablation can be another treatment option in addition to surgical resection. For those with 2-3 cancer foci located in different areas and poor liver function that cannot undergo resection surgery, including those with liver function Child-Pugh grade B or up to grade B after liver preservation therapy, local ablation therapy can be considered. For hepatocellular carcinoma of deep or central liver type ≤3 cm, local ablation can achieve the efficacy of surgical resection and obtain radical ablation under minimally invasive treatment, which can be preferred; for hepatocellular carcinoma of 3-5 cm, the therapeutic effect can be improved by selecting appropriate instrumentation needle, mastering reasonable ablation technique and accumulating certain treatment experience, etc. It is generally believed that most patients also need comprehensive adjuvant therapy after local ablation. There is a lack of research data comparing local ablation therapy with liver transplantation and anatomical hepatectomy. For larger hepatocellular carcinoma (>5 cm), whether multi-point or fractional ablation or open or laparoscopic ablation can be performed, there is also a lack of sufficient evidence-based medical evidence for reference, and it is not recommended.