I. Overview Primary liver cancer (PLC, hereinafter referred to as liver cancer) is a common malignant tumor. Because of insidious onset, no or no obvious symptoms in early stage and rapid progress, most patients have already reached advanced local stage or distant metastasis when diagnosed, which makes treatment difficult and prognosis very poor. Wang Yuehua, Department of General Surgery, Xuanwu Hospital, Capital Medical University Primary liver cancer mainly includes different pathological types such as hepatocellular carcinoma (HCC), intrahepatic cholangiocarcinoma (ICC) and mixed hepatocellular carcinoma-intrahepatic cholangiocarcinoma, which have obvious differences in their pathogenesis, biological behavior, histological pattern, clinical manifestations, treatment methods and prognosis. Therefore, the term “hepatocellular carcinoma” in this paper mainly refers to HCC. Diagnostic techniques and applications (a) Surveillance and screening of high-risk groups. The etiological factors of liver cancer in China include hepatitis virus infection, aflatoxin contamination of food, long-term alcohol abuse and blue-green algae contamination of rural drinking water, other liver metabolic diseases, autoimmune diseases and cryptogenic liver disease or cryptogenic cirrhosis. Since early diagnosis of liver cancer is crucial for effective treatment and long-term survival, early screening and early surveillance of liver cancer are highly emphasized. Routine surveillance screening indicators mainly include serum alpha-fetoprotein (AFP) and liver ultrasonography (US). Screening is generally performed at 6-month intervals for men ≥40 years of age or women ≥50 years of age with HBV and/or HCV infection, alcoholism, comorbid diabetes mellitus, and a family history of liver cancer in high-risk groups. It is generally believed that AFP is a relatively specific tumor marker for HCC, and persistent elevation of AFP is a risk factor for the development of HCC. Newly, some European and American scholars believe that the sensitivity and specificity of AFP is not high, and the 2010 edition of the American Association for the Study of Liver Diseases (AASLD) guidelines no longer use AFP as a screening indicator, but most of HCC in China is associated with HBV infection, which is different from the causative factors of HCC in Western countries (mostly HCV, alcohol and metabolic factors), and combined with the results of domestic randomized studies (RCT) and the actual (b) Clinical manifestations. 1. Symptoms. Pre-subclinical stage of hepatocellular carcinoma refers to the period from the beginning of the lesion to the diagnosis of subclinical hepatocellular carcinoma, when patients have no clinical symptoms and signs and are difficult to be detected clinically, usually about 10 months. In the subclinical stage (early stage) of hepatocellular carcinoma, the tumor is about 3-5 cm, most patients still have no typical symptoms, so the diagnosis is still difficult, and it is mostly detected by serum AFP census for about 8 months on average, during which a few patients can have symptoms related to chronic underlying liver disease such as epigastric distention, abdominal pain, weakness and loss of appetite. Therefore, for those with high-risk factors, the possibility of hepatocellular carcinoma should be alerted to the occurrence of the above-mentioned conditions. Once the typical symptoms appear, the disease has often reached the middle or advanced stage of liver cancer, at this time, the disease develops rapidly, with a total of about 3-6 months, and its main manifestations are: (1) Pain in the liver area. Pain in the right upper abdomen is the most common and is an important symptom of the disease. It is often intermittent or persistent vague, dull or distending pain, which increases with the development of the disease. If the tumor invades the diaphragm, the pain may spread to the right shoulder or the right back; the tumor growing backward to the right may cause pain in the right lumbar region. The cause of pain is mainly due to the tumor growth which makes the liver envelope tense. The sudden occurrence of severe abdominal pain and peritoneal irritation sign may be caused by peritoneal irritation due to rupture and bleeding of subperitoneal cancer nodules. (2) Loss of appetite. The symptoms of epigastric fullness after meals, indigestion, nausea, vomiting and diarrhea are easily ignored because of the lack of specificity. (3) Wasting and weakness. The whole body is weak, and a few advanced patients may present a cachectic condition. (4) Fever. It is more common, mostly persistent low fever, about 37.5-38℃, or irregular or intermittent, persistent or chills type high fever, similar to liver abscess, but no chills before fever, and antibiotic treatment is ineffective. The fever is mostly cancer fever, which is related to the absorption of tumor necrotic material; sometimes it can be caused by cholangitis due to the compression or invasion of bile duct by cancer, or fever due to other infections combined with weakened resistance. (5) Symptoms of extra-hepatic metastases. For example, lung metastasis may cause cough and hemoptysis; pleural metastasis may cause chest pain and bloody pleural effusion; bone metastasis may cause bone pain or pathological fracture, etc. (6) Jaundice, bleeding tendency (gingival, nasal bleeding and subcutaneous bruises), upper gastrointestinal bleeding, hepatic encephalopathy and hepatic and renal failure are often seen in advanced stage patients. (7) Paraneoplasticsyndrome, which is a syndrome of endocrine or metabolic disorders caused by the abnormal metabolism of liver cancer tissue itself or the multiple effects of cancer tissue on the body. The clinical manifestations are diverse and lack of specificity, such as spontaneous hypoglycemia, erythrocytosis, hyperlipidemia, hypercalcemia, precocious puberty, gonadotropin secretion syndrome, cutaneous porphyria, abnormal fibrinogenemia and carcinoid syndrome, etc., but they are relatively rare. 2. Physical signs. In the early stage of hepatocellular carcinoma, most patients do not have obvious positive signs. Only a few patients can find mild hepatomegaly, jaundice and skin pruritus on physical examination, which should be non-specific manifestations of underlying liver disease. In the middle and advanced stages of hepatocellular carcinoma, jaundice, liver enlargement (hard texture, uneven surface, with or without nodules, vascular murmur) and peritoneal effusion are common. If there is a background of hepatitis or cirrhosis, liver palm, spider nevus, red mole, abdominal wall varices and splenomegaly can be found. (1) Liver enlargement: it is often progressively enlarged, with hard texture, uneven surface, nodules of different sizes or even giant lumps, with clear edges, and often with varying degrees of tenderness and pressure pain. If the hepatocellular carcinoma protrudes to the right subcostal arch or subxiphoid process, the corresponding area can be seen to be locally full and elevated; if the carcinoma is located on the diaphragmatic surface of the liver, the diaphragm is mainly elevated in a restricted manner without enlargement of the lower edge of the liver; the carcinoma nodules located on the surface of the liver near the lower edge are most easily palpable. (2) Vascular murmur: Due to the rich and tortuous blood vessels of hepatocellular carcinoma and the sudden thinning of arteries or the compression of hepatic artery and abdominal aorta by cancer mass, about half of the patients can hear wind-like vascular murmur in the corresponding area; this sign has important diagnostic value, but it is not significant for early diagnosis. (3) Jaundice: yellow staining of the skin and sclera, often appearing in the late stage, mostly due to obstruction of the bile duct caused by the cancer or enlarged lymph nodes, or due to damage to hepatocytes. (4) Portal hypertension: Patients with hepatocellular carcinoma mostly have cirrhotic background, so they often have portal hypertension and splenomegaly. Bloody effusion is mostly caused by cancer breaking into the peritoneal cavity, and can also be caused by peritoneal metastasis; portal vein and hepatic vein cancer embolism can accelerate the growth of peritoneal effusion. 3.Infiltration and metastasis. (1) Intrahepatic metastasis: initially, most hepatocellular carcinoma is intrahepatic metastasis, which easily invades portal vein and its branches and forms tumor embolus, and then causes multiple metastases in the liver after dislodging. If the tumor thrombus of the trunk branch of portal vein is obstructed, it will often cause or aggravate the existing portal hypertension. (2) Extrahepatic metastasis: ①Lung metastasis is the most common, but it can also be metastasized to the pleura, adrenal gland, kidney and bone. (2) Lymphatic metastasis, with metastasis to the hilar lymph nodes being the most common, but also to the pancreas, spleen and para-aortic lymph nodes, and occasionally to the supraclavicular lymph nodes. Occasionally, the metastasis can be planted in the peritoneum, diaphragm and thorax, causing bloody abdominal and thoracic fluid; in women, ovarian metastasis can occur and form larger masses. 4.Common complications. (1) Upper gastrointestinal bleeding: Hepatocellular carcinoma often has hepatitis and cirrhosis background with portal hypertension, and portal vein and hepatic vein cancer thrombus can further aggravate portal hypertension, so it often causes bleeding from varices of middle and lower esophagus or gastric fundus. If cancer cells invade the bile duct, it may cause biliary bleeding, vomiting blood and black stool. Some patients may bleed extensively due to gastrointestinal mucous membrane erosion, ulceration and coagulation dysfunction, which may lead to shock and hepatic coma. (2) Hepatorenal nephropathy and hepatic encephalopathy (hepatic coma): In advanced stage of hepatocellular carcinoma, especially diffuse hepatocellular carcinoma, hepatic insufficiency or even failure can occur, causing hepatorenalsyndrome (HRS), i.e. functional acute renal failure (functional acuterenalfailure, FARF), which mainly manifests as Significant oliguria and decreased blood pressure with hyponatremia, hypokalemia and azotemia, often progressive in development. Hepatic encephalopathy (HE), i.e. hepatic coma, is often a manifestation of end-stage hepatocellular carcinoma, often induced by gastrointestinal bleeding, massive diuretics, electrolyte disturbance and secondary infection. (3) Rupture and bleeding of hepatocellular carcinoma nodules: It is the most urgent and serious complication of hepatocellular carcinoma. Therefore, when palpating the nodule during clinical examination, it is recommended to be gentle and not to press hard. The rupture of cancer nodules can be confined to the subhepatic peritoneum, causing acute pain and rapid enlargement of the liver, and soft masses can be palpated locally. A small amount of bleeding can be manifested as bloody peritoneal fluid, while a large amount of bleeding can lead to shock or even rapid death. (4) Secondary infection: Due to long-term consumption and bed-rest, patients with liver cancer have weakened resistance, especially after chemotherapy or radiotherapy when their white blood cells are reduced, they are prone to complications of various infections, such as pneumonia, intestinal infection, fungal infection and sepsis, etc. (iii) Auxiliary examination. 1.Blood biochemical examination. Hepatocellular carcinoma can show abnormal liver function such as elevation of portal aminotransferase (AST or GOT) and glutamate aminotransferase (ALT or GPT), serum alkaline phosphatase (AKP), lactate dehydrogenase (LDH) or bilirubin, and decrease of albumin, as well as changes of immune indexes such as lymphocyte subpopulation. Positive hepatitis B surface antigen (HBsAg) or five quantitative tests (including HBsAg, HBeAg, HBeAb and anti-HBc) and/or positive hepatitis C antibodies (anti-HCVIgG, anti-HCVst, anti-HCVns and anti-HCVIgM) are all important signs of hepatitis virus infection. HBVDNA and HCVmRNA can reflect hepatitis viral load. 2. Tumor marker examination. Serum AFP and its heteroplasm are important indicators and the most specific tumor markers for the diagnosis of hepatocellular carcinoma, and are commonly used in China for the screening, early diagnosis, postoperative monitoring and follow-up of hepatocellular carcinoma. For AFP ≥ 400 μg/L for more than 1 month or ≥ 200 μg/L for 2 months, excluding pregnancy, germinal gland embryonal carcinoma and active liver disease, liver cancer should be highly suspected; the key is whether imaging examination (CT/MRI) with characteristic occupancy of liver cancer is performed at the same time. AFP may not be increased in 30%-40% of patients with hepatocellular carcinoma, including those with ICC, highly differentiated and hypofractionated HCC, or HCC with necrotic liquefaction. Therefore, AFP alone cannot diagnose all hepatocellular carcinoma. The positive rate of AFP for hepatocellular carcinoma diagnosis is generally 60%-70%, and sometimes it varies greatly, emphasizing the need for regular testing and dynamic observation, and the need for imaging or even ultrasound-guided puncture biopsy to clarify the diagnosis. Other markers that can be used to aid in the diagnosis of HCC are various serum enzymes, including r-glutamyl transpeptidase (GGT) and its isoenzymes, alpha-L-arginase (AFU), abnormal prothrombin (DCP), Golgi protein 73 (GP73), 5-nucleotide phosphodiesterase (5’NPD) isoenzyme, aldolase isoenzyme A (ALD -A) and placental-type glutathione S-transferase (GST), as well as abnormal prothrombin (DCP), ferritin (FT) and acid ferritin (AIF). In some HCC patients, there may be abnormal increase of carcinoembryonic antigen (CEA) and glycoantigen CA19-9, etc. 3.Imaging examination. (1) Abdominal ultrasound (US) examination: US examination has become the most common and important method for liver examination because of its easy operation, intuition, non-invasiveness and low cost. It can determine whether there are occupying lesions in the liver, suggest their nature, identify whether they are fluid or substantial occupations, clarify the specific location of cancer foci in the liver and their relationship with important blood vessels in the liver, so as to guide the selection of treatment methods and surgery; it helps to understand the spread and infiltration of hepatocellular carcinoma in the liver and adjacent tissues and organs. It is of great reference value for the differential diagnosis of hepatocellular carcinoma and liver cysts, hepatic hemangioma and other diseases, but its sensitivity and qualitative accuracy are somewhat affected by the limitations of instrumentation, anatomical location, operator’s technique and experience. Real-time US imaging (ultrasonography CEUS) can dynamically observe the hemodynamic situation of the lesion and help improve the qualitative diagnosis, but it can be false positive for patients with ICC and should be noted; while intraoperative US probes directly from the surface of the liver after opening, which can avoid ultrasound attenuation and interference from the abdominal wall and ribs, and can detect small intrahepatic lesions that are not detected by preoperative imaging. (2) Computed tomography (CT): It is the most important imaging method for diagnosis and differential diagnosis of hepatocellular carcinoma, and is used to observe the morphology and blood supply of hepatocellular carcinoma, to detect, characterize and stage hepatocellular carcinoma, and to review hepatocellular carcinoma after treatment. The minimum layer thickness is 0.5mm, which significantly improves the detection rate and qualitative accuracy of small lesions of liver cancer. Usually, under plain scan, most hepatocellular carcinomas are low-density occupants with clear or blurred edges, and some of them have halo signs, and large hepatocellular carcinomas often have central necrosis and liquefaction; it can indicate the nature of lesions and understand whether there are cancer foci in the surrounding tissues and organs of the liver, which can help the localization of radiotherapy; in addition to clearly showing the number, size, morphology and intensification characteristics of lesions, enhanced scan can also clarify the relationship between lesions and important blood vessels, and the relationship between the hilum and the abdomen. The imaging of HCC is typical in the arterial phase with significant enhancement, but in the venous phase with less enhancement than the surrounding liver tissue, and in the delayed phase with continuous fading of the contrast, so it is highly specific. (3) Magnetic resonance imaging (MRI or MR): no radioactive radiation, high tissue resolution, multi-directional and multi-sequence imaging, better display and resolution than CT and US for the internal structural changes of liver cancer lesions, such as hemorrhagic necrosis, steatosis and envelope; it may be better than CT for the differentiation of benign and malignant intrahepatic occlusions, especially with hemangioma; meanwhile, it can show the branches of portal vein and hepatic vein without enhancement. For small hepatocellular carcinoma, MRI is superior to CT, and there is more evidence. In particular, the increasing popularity and development of high-field strength MR equipment has greatly accelerated the speed of MR scanning, which can be completed with the same thin layer and multi-phase dynamic enhancement scan as CT, fully displaying the enhancement characteristics of the lesion and improving the detection rate and qualitative accuracy of the lesion. In addition, MR functional imaging techniques (such as diffusion-weighted imaging, perfusion-weighted imaging, and spectral analysis) and the application of hepatocyte-specific contrast agents can provide valuable additional information for lesion detection and characterization, which can help further improve the sensitivity and accuracy of hepatocellular carcinoma detection and characterization as well as the comprehensive and accurate assessment of the efficacy of various local treatments. The above three important imaging techniques have their own characteristics and complementary advantages, and should be emphasized for comprehensive examination and overall assessment. (4) Selective hepatic arteriography (DSA): Currently, digital subtraction angiography is mostly used to clearly show small lesions in the liver and their blood supply, while chemotherapy and iodine oil embolization can be performed. The main manifestations of hepatocellular carcinoma in DSA are: ① tumor vessels, which appear in the early arterial phase; ② tumor staining, which appears in the parenchymal phase; ③ larger tumors can be seen as displacement, straightening and twisting of intrahepatic arteries; ④ intrahepatic arteries invaded by hepatoma can appear as jagged, beaded or stiff; ⑤ arteriovenous fistula; “pool-like” or (5) arteriovenous fistula; “pool” or “lake” contrast-filled area, etc. The significance of DSA examination not only lies in the diagnosis and differential diagnosis, but also can be used to estimate the extent of the lesion before surgery or treatment, especially to understand the situation of disseminated sub-nodules in the liver; it can also provide correct and objective information on the anatomical variation of vessels and the anatomical relationship of important vessels as well as portal vein infiltration, which is of great value in judging the possibility and completeness of surgical resection and deciding on a reasonable treatment plan. DSA is an invasive DSA is an invasive test and can be used for patients whose diagnosis cannot be confirmed after other tests. In addition, for resectable hepatocellular carcinoma, even if the imaging presentation is limited resectable hepatocellular carcinoma, some scholars advocate preoperative DSA, which has the potential to detect lesions that cannot be detected by other imaging means and to clarify the presence of vascular invasion. (5) Positron emission computed tomography (PET-CT): PET-CT is a functional molecular imaging system integrating PET and CT, which can reflect the biochemical and metabolic information of liver occupancy by PET functional imaging and precisely locate the lesion by CT morphological imaging, and the whole-body scan can understand the overall condition and evaluate the metastasis to achieve early detection of the lesion. The purpose of early detection of lesions can be achieved, and the size and metabolic changes before and after tumor treatment can be understood. However, the sensitivity and specificity of PET-CT for clinical diagnosis of hepatocellular carcinoma need to be further improved, and it is not yet commonly used in most hospitals in China. (6) Emission single-photon computed tomography (ECT): ECT whole-body bone imaging is helpful for the diagnosis of bone metastasis of liver cancer and can detect bone metastasis 3-6 months earlier than X-ray and CT examination. 4. Liver aspiration biopsy. Histological or cytological examination by percutaneous liver aspiration with hollow needle biopsy (Corebiopsy) or fine needle aspiration (Fineneedleaspiration, FNA) under ultrasound guidance can obtain the pathological diagnosis of hepatocellular carcinoma as well as molecular markers, which are very important for definite diagnosis, pathological type, judgment of disease, guidance of treatment and assessment of prognosis. It is very important for definite diagnosis, pathological type, judgment, treatment and prognosis, and has been increasingly used in recent years, but it also has certain limitations and risks. When performing liver aspiration biopsy, care should be taken to prevent liver bleeding and needle tract cancer cell implantation; contraindications are patients with significant bleeding tendency, severe cardiopulmonary, cerebral and renal disorders and systemic failure.