Although surgery is the preferred treatment for primary hepatocellular carcinoma, most patients are already in the middle and late stages at the time of diagnosis and are often deprived of surgical opportunities, and according to statistics, only about 20% of patients are suitable for surgery. Therefore, non-surgical treatment should be actively adopted, which may reduce the symptoms, improve the quality of life and prolong the survival of a considerable number of patients. (i) Local ablation therapy. Local ablation therapy is a type of treatment that uses physical or chemical methods to kill tumor tissues directly with the guidance of medical imaging technology to target and locate the tumor. It mainly includes radiofrequency ablation (RFA), microwave ablation (MWA), cryoablation, high power focused ultrasound ablation (HIFU) and anhydrous ethanol injection (PEI), which are minimally invasive, safe, simple and easy to perform multiple times. Image 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. Liver function classification of Child-Pugh grade A or B, or with medical liver care to achieve this standard. 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 treatment; ⑤ ruptured esophagogastric fundic variceal bleeding within 1 month before treatment; ⑥ un correctable coagulation dysfunction and obvious blood abnormalities with obvious bleeding tendency; ⑦ persistent massive ascites, malignant fluid; ⑧ combined with active infection, especially inflammation of bile duct system, etc.; ⑨ 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 envelope 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 liver cancer, and also the most widely used thermal ablation method. For patients with small hepatocellular carcinoma, the long-term efficacy of RFA is similar to that of liver transplantation and hepatectomy, and is superior to TAE/TACE treatment alone. Compared with anhydrous ethanol injection, RFA has 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. Tumors with rich blood supply can be coagulated to block the main trophoblastic vessels of the tumor before inactivating the tumor, which can improve the efficacy. Establishing a temperature monitoring system can regulate the effective thermal field range and ensure the coagulation effect. (3) ercutaneous ethanol injection (PEI): It is suitable for the treatment of small hepatocellular carcinoma with diameter ≤3 cm and recurrent small hepatocellular carcinoma. It can also serve as palliative treatment for liver cancer or recurrent foci that are not suitable for surgery above >3 cm. Clinically, some cancer foci are close to the hilar, gallbladder and gastrointestinal tract tissues, and thermal ablation treatment (RFA and MWA) may easily cause damage; in this case, 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 versus MWA) can achieve similar long-term survival outcomes as surgical resection for small hepatocellular carcinoma; however, compared with both, 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 hepatocellular carcinoma ≤5 cm. For hepatocellular carcinoma ≤5 cm that meets the indications of both local surgical treatment and ablation treatment, surgical treatment should be 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 be resected, including those with liver function Child-Pugh grade B or up to grade B after hepatoprotective therapy, local ablation therapy can be considered. For hepatocellular carcinoma of deep or central 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. It is generally believed that most patients need to adopt 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 fractionated ablation or open or laparoscopic ablation can be performed, there is not enough evidence-based medical evidence for reference, so it is not recommended. (B) Hepatic artery intervention. 1. Basic principles. (1) It is required to be performed under digital subtraction angiography machine; (2) clinical indications must be strictly mastered; (3) standardization and individualization of treatment must be emphasized. 2. Applicable groups. (1) Patients with intermediate and advanced primary liver cancer who cannot be surgically resected; (2) Patients who can be surgically resected but cannot or do not want to undergo surgery due to other reasons (such as advanced age, severe cirrhosis, etc.). For the above patients, interventional therapy can be the preferred method among non-surgical treatments. Domestic clinical experience shows that hepatic artery intervention is effective for giant hepatocellular carcinoma with relatively intact envelope and large hepatocellular carcinoma, but for hepatocellular carcinoma that can be surgically resected, surgical resection is preferred. The main influencing factors of interventional therapy are: ① serum AFP level; ② whether the tumor lesion has intact envelope and clear boundary; ③ whether there is cancer thrombus in portal vein. 3. Indications. (1) The main indications for TACE are: (1) middle and advanced HCC that cannot be surgically resected, without serious liver and kidney dysfunction, including: (1) massive hepatocellular carcinoma: the proportion of tumor in the whole liver is <70%; (2) multiple nodular hepatocellular carcinoma; (3) portal vein trunk is not completely obstructed, or although completely obstructed, compensatory collateral vessels between hepatic artery and portal vein are formed; (4) failed surgical operation or postoperative recurrence; (5) liver function classification (Child-Pugh) A or B; and (6) liver function classification. Child-Pugh) grade A or B, ECOG score 0-2; (6) ruptured hepatic tumor bleeding and portal hypertensive bleeding caused by hepatic artery - portal vein static shunt. (2) It is applied before liver tumor resection, which can shrink the tumor and facilitate second-stage resection, as well as clarify the number of lesions; (3) small hepatocellular carcinoma, but not suitable or unwilling for surgery, local radiofrequency or microwave ablation treatment; (4) control of local pain, bleeding and embolization of arteriovenous impotence; (5) after hepatectomy, to prevent recurrence. 4. Contraindications. (1) severe impairment of liver function (Child-Pugh grade C); (2) severely diminished coagulation function that cannot be corrected; (3) portal vein trunk completely embolized by cancer emboli and little formation of collateral vessels; (4) combined active infection and cannot be treated simultaneously; (5) distant and extensive metastasis of tumor with estimated survival <3 months; (6) cachexia or multi-organ failure; (7) Tumor accounts for ≥70% of the whole liver cancer foci; if liver function is basically normal, a small amount of iodine oil emulsion can be considered for fractional embolization; (8) significant reduction of peripheral blood leukocytes and platelets, leukocytes <3.0×109/L (not absolutely contraindicated, such as those with hypersplenism, which is different from chemotherapeutic leukopenia), platelets <60×109/L. 5. Operation procedure points and classification. Basic operations: hepatic arteriography, usually using the Seldinger method, percutaneous puncture femoral artery cannulation, catheter placed in the abdominal trunk or common hepatic artery imaging, imaging image acquisition should include the arterial phase, parenchymal phase and venous phase; superior mesenteric artery imaging should be done, pay attention to the search for collateral blood supply. (1) Hepatic artery infusion chemotherapy (TAI): After careful analysis of the imaging performance, the site, size, number and blood supply artery of the tumor should be clearly defined, then super-selective intubation into the blood supply artery of the tumor should be performed to give infusion chemotherapy, and the commonly used chemotherapeutic drugs are Adriamycin (ADM) or Epi-Adriamycin (EADM), Cisplatin (PDD), 5-Fluorouracil (5-Fu), Hydroxycitric acid (HCP), and Hepatitis B (HCP). Hydroxycamptothecin (HCPT) and mitomycin (MMC). (2) Hepatic artery embolization (TAE): it is commonly used clinically, and super-selective cannulation should be adopted whenever possible, and attention should be paid to the selection of appropriate embolic agents. The amount of iodine oil should be controlled according to the size of the tumor, blood supply and the number of tumor supplying arteries, and other embolic agents such as gelatin sponge, permanent particles and microspheres can also be used. For hepatocellular carcinoma combined with arteriovenous fistula, it should be noted that firstly, the arteriovenous fistula should be effectively embolized and blocked, and then TAE for tumor should be performed to prevent serious complications such as pulmonary embolism and to ensure the effect of anti-tumor TAE; for severe arteriovenous fistula, it is generally advocated to take TAI treatment only. (3) Hepatic artery embolization chemotherapy (TACE): Hepatic artery infusion chemotherapy (TAI) and hepatic artery embolization (TAE) are performed simultaneously to improve the efficacy. TACE can effectively block the arterial blood supply of hepatocellular carcinoma, while releasing high concentrations of chemotherapeutic drugs to combat the tumor, causing ischemic necrosis and shrinkage, with less impact on normal liver tissue. Evidence-based medical evidence has shown that TACE can effectively control the growth of hepatocellular carcinoma, significantly prolong the survival of patients, and benefit patients with hepatocellular carcinoma, which has become the first and most effective treatment method for middle and advanced hepatocellular carcinoma that cannot be surgically resected. Before TACE, we should analyze the imaging performance, clarify the tumor site, size, number and blood supplying artery, and then super-select the cannula to the right hepatic artery and left hepatic artery to give perfusion chemotherapy respectively. The head end of the catheter should cross the gallbladder, the right gastric artery and the gastroretinal artery and other vessels. In most HCC, more than 95% of the blood supply comes from the hepatic artery, which is characterized by thickened blood supply arteries, abundant tumor vessels and dense tumor staining. Embolization should be performed after perfusion chemotherapy. It is advocated that super-liquefied ethyl iodide oil and chemotherapeutic drugs should be fully mixed into an emulsion, and the mixture should be slowly injected into the target vessel through a microcatheter super-selectively inserted into the blood supplying arterial branch of the tumor. Embolization should be performed to avoid embolization of normal liver tissue or into non-target organs. For patients with hepatocellular carcinoma with markedly thickened blood supply arteries, it is usually advisable to add granular embolic agents (e.g. gelatin sponge or microspheres) after the iodine oil emulsion embolization. Embolization should try to embolize all the feeding vessels of the tumor in order to de-vascularize the tumor. Care should be taken not to completely occlude the intrinsic hepatic artery to facilitate re-TACE treatment. The main factors affecting the long-term efficacy of TACE include the degree of cirrhosis, the functional status of the liver and the tumor condition (size, grade, pathological type, portal vein carcinoma thrombus, and arteriovenous fistula). In addition, TACE treatment itself has some limitations, which are: (1) TACE is often difficult to achieve complete necrosis due to incomplete embolization and establishment of tumor collateral vessels; (2) after TACE treatment, the level of hypoxia-inducible factor (HIF) in the residual tumor increases due to ischemia and hypoxia of the tumor tissue, resulting in high expression of vascular endothelial growth factor (VEGF). These factors can lead to intrahepatic tumor recurrence and distant metastasis. 6. Common adverse effects after TACE. Post-embolization syndrome is the most common adverse effect of TACE treatment, mainly manifested as fever, pain, nausea and vomiting. Fever and pain occur because of local tissue ischemia and necrosis caused by embolization of hepatic artery, while nausea and vomiting are mainly related to chemotherapy drugs. In addition, there are other common adverse effects such as bleeding at the puncture site, white blood cell drop, transient liver function abnormalities, renal function impairment and difficulty in urination. Generally, the adverse reactions after interventional therapy will last for 5-7 days, and most patients can fully recover after symptomatic treatment. 7. Follow-up and treatment interval. It is generally recommended to review CT and/or MRI etc. at 4-6 weeks after the first hepatic artery intervention; as for the follow-up review, it can be 1-3 months apart depending on the patient's specific situation. The frequency of intervention should depend on the follow-up results. If the imaging shows dense iodine oil deposits in the liver at 4-6 weeks after the intervention, necrosis of the tumor tissue and no enlargement or new lesions, no further intervention should be done for the time being. The interval between the initial 2-3 interventions can be short. Thereafter, the treatment interval should be prolonged in the absence of tumor progression to ensure the recovery of liver function. During the treatment interval, the survival of liver tumor can be evaluated using CT and/or MRI dynamic enhancement scans to decide whether another interventional treatment is needed. If the tumor continues to progress after several interventions, switching to or combining with other treatments, such as surgery, local ablation and systemic therapy, should be considered.