Clinical practice and literature reports suggest [1, 2] that 40-90.2% of patients with advanced hepatocellular carcinoma form cancer thrombi in the main trunk or major branches of the portal vein. In 2003, Chau et al [3] studied 37 surgically resected specimens of hepatocellular carcinoma less than 50px in diameter and found that the incidence of microscopic portal vein thrombosis was 40.5%, whereas in 115 surgically resected specimens of hepatocellular carcinoma 2.1-100px in diameter, the incidence of portal vein thrombosis was as high as 49.6%. The incidence of cancer embolism is not only high, but also a major factor affecting the prognosis of hepatocellular carcinoma. In recent years, the treatment of hepatocellular carcinoma has made great progress, but the treatment of cancer embolism not only has few methods, but also has limited efficacy, which has become a very difficult problem in clinical hepatocellular carcinoma. Based on our clinical practice and research, this article discusses our shallow experience on the typing and treatment selection of portal vein cancer embolism. 1.Typing of portal vein cancer embolus Because of the different performance of cancer embolus in terms of location and development, the prognosis varies greatly, and it is difficult to scientifically judge the efficacy of various treatment methods in clinical practice, and even more difficult to accurately judge the prognosis. Therefore, it is particularly important to establish a scientific staging standard for cancer thrombosis to guide clinical practice. Based on the growth pattern and characteristics of cancer thrombus and the anatomical characteristics of portal vein, we have established a staging standard for portal vein cancer thrombus: according to the development degree of cancer thrombus (i.e. invading different portal vein sites) [4], cancer thrombus is classified into type I-IV, i.e. type I for cancer thrombus involving more than two branches of portal vein, type II for cancer thrombus involving one branch of portal vein, type III for cancer thrombus involving main portal vein, and type IV for cancer thrombus involving superior mesenteric or type IV if it involves the superior mesenteric vein or inferior vena cava. Each subtype is further divided into 2 subtypes (see Table 1). This typing can objectively reflect the patient’s disease stage and prognosis. In the past, there was no good reference for the treatment of portal vein cancer embolism, and different treatments were generally chosen according to the experience of the doctor and his or her different interests in the specialty, which resulted in inappropriate treatment or over-treatment. We propose the following treatment options according to the different staging of portal vein cancer thrombosis, combined with evidence from evidence-based medicine related literature (Exhibit 1): patients with Child A or B are first selected for further treatment according to the liver function Child classification. Patients with Type I, II, and IIIa tumors that meet the Milan criteria are recommended for surgical resection, while Type IIIb tumors are recommended for half-dose radiation therapy followed by surgical resection in January. For patients who do not meet Milan’s criteria, in principle, if the primary tumor is confined to half of the liver, surgical resection can be considered regardless of type I, II, or III. If the primary tumor is not confined to the hemihepatic area or multiple tumors, TACE plus/ or radiotherapy combined with the molecular targeting drug Sorafenib [5] (Sorafeni) is the treatment of choice. For special cancer embolism such as type IV cancer embolism, the general surgical efficacy is extremely poor, and in principle, subsurgical treatment such as TACE plus radiotherapy combined with Sorafeni is considered. 3.Surgical treatment of portal vein cancer embolism Surgical resection is one of the treatment methods for hepatocellular carcinoma with portal vein cancer embolism, and it is also the most curable method among all treatment methods. Most of the cancer thrombi develop in the direction of the main tumor as the base of the portal vein trunk, which determines that surgical resection can remove both the main tumor and the cancer thrombus at the same time. Even if the cancer embolus cannot be completely removed, it can still achieve the goal of eliminating the tumor and reducing the burden, unblocking the blood vessels, reducing the portal vein pressure and improving the quality of survival. Generally speaking, if it is a microvascular thrombus or microscopic thrombus (type I0 thrombus), as long as the margin is sufficient, it can be cured, and if the thrombus is located in the tertiary branch, secondary branch (type I thrombus), or even primary branch (type II thrombus) of portal vein, as long as it can be removed, it can be cured. There is still controversy about the surgical resection of cancer embolus in the main trunk of portal vein, but I believe that surgical resection should be preferred for type IIIa cancer embolus. For type IIIb and type IV emboli, TACE plus local radiation therapy is generally recommended because of the poor surgical efficacy. Surgical resection should be strictly controlled by surgical indications. At present, there is no unified understanding of the surgical indications, and the preoperative resectability estimation varies greatly among families. In general, if the liver function is basically normal, there is no ascites, the hepatocellular carcinoma is limited, the tumor is single or only peripheral scattered foci, the main tumor is estimated to be resectable, the remaining liver is still compensable, and there is no distant metastasis, surgical resection + portal vein thrombectomy is feasible. We found [6] that surgical resection of type I carcinoma thrombus has the best efficacy and surgery is the best option for it, while type IV is not suitable for surgery. Therefore, we suggest that the indications for surgical resection are: type I and type II are suitable for surgical resection. type III is a relative indication. type IV should be a contraindication. 4. Interventional chemoembolization of portal vein cancer thrombus (TACE) TACE or TAE is currently the most commonly applied method in the non-surgical treatment of unresectable hepatocellular carcinoma [7]. Regarding the indications for TACE, portal vein cancer embolism has been listed as its contraindication in the past. However, recent studies have shown that most of the portal vein thrombi formed in hepatocellular carcinoma are formed gradually and slowly, and the body has the ability to compensate, with small periportal veins dilating and forming collateral circulation, and the serpentine venous plexus parallel to the main trunk of portal vein is visible on angiography. These patients are often in good general condition, without ascites, and with basically normal liver function, and TACE is feasible for them. Some authors believe that TACE can be performed as long as the portal vein trunk is not blocked by more than 50% of the portal vein lumen, but not vice versa. In conclusion, TACE can be considered for patients with hepatocellular carcinoma combined with portal vein thrombosis as long as their liver function is acceptable, there is no obvious ascites or severe jaundice and there are no obvious systemic contraindications. In clinical practice, it is found that some patients have good filling of iodine oil in portal vein trunk cancer thrombus after TACE treatment, which has a great inhibitory effect on controlling the development of cancer thrombus. Therefore, we suggest that the indications for TACE treatment of portal vein cancer embolism are: type I and type II are suitable for TACE treatment; type III is a relative indication; type IV should be a contraindication. 5.Radiation therapy for portal vein cancer embolism Radiation therapy (radiotherapy for short) refers to the treatment of tumors with isotope rays, high-energy X-rays generated by gas pedals, electron beams, protons, fast neutrons, negative л mesons and other heavy particles. Generally, there are two types of radiation therapy, one is long-distance radiation, that is, the radiation source is irradiated at a certain distance from the human body, and the radiation penetrates from the body surface into the body to a certain depth to achieve the purpose of treating tumors. The other is brachytherapy, in which the radiation source is sealed in the body cavity or inserted between tissues. Indications for cancer embolism radiotherapy: ①One of the comprehensive treatments for unresectable liver cancer, cancer embolism is confined to the portal vein on the same side of the tumor. ②Surgical resection of tumor and portal vein cancer embolus, but it is estimated that the portal vein cancer embolus has not been removed. ③Recurrent cancer thrombus. Recurrent cancer thrombus is found in the portal vein, but no metastatic recurrence is found in the liver. In addition, preoperative radiotherapy can be done first to shrink the larger tumor (combined with cancer embolus) before resection, which can significantly improve the resection rate. Currently, the main internal radiation therapies used for clinical treatment of hepatocellular carcinoma and its portal vein cancer thrombus are 133I, 125I, 90Y, 32P, etc. They can kill the remaining cancer cells around the tumor in the portal vein blood supply area, and can directly kill the cancer thrombus in the portal vein branch of the tumor area. Radiation therapy has increasingly become the main means and method of portal vein cancer embolism treatment, and literature reports [8] and clinical practice have proved that radiation therapy, especially localized conformal radiotherapy, plays an important role in inhibiting the growth of cancer emboli and improving the overall outcome of patients with portal vein cancer embolism in liver cancer.