# The Recent Development of the Surgical Treatment for Hepatocellular Carcinoma
## 4 Surgical Treatment of Highly Advanced HCC Outside Milan Criteria
### Liver Resection for HCC with Hepatic Vein Tumor Thromus  
Unlike HCC with PVTT, HCC with hepatic vein tumor thrombus (HVTT) accounts for only about 5% of all HCC cases [9]. HVTT is categorized as tumor thrombus in a peripheral hepatic vein, including microvascular invasion (pHVTT, Vv1), in a major hepatic vein (mHVTT, Vv2), or in the inferior vena cava (IVCTT, Vv3) according to the Japanese staging system [40]. In 2017, [PERSON] et al. reported the outcomes of 1266 HCC patients with HVTT in Japan [41]. The surgical outcome for p/mHVTT was excellent, with a MST of 53.6 months and a five-year survival rate of 44.2%. In a propensity score-matched cohort, the MST of the liver resection group was 19.3 months longer than the non-liver resection group (41 months vs. 21.7 months). On the other hand, PVTT was an independent poor prognostic factor in the p/mHVTT resection group, and the MST of patients with PVTT was 45.4 months shorter than the patients without PVTT (22.6 months vs. 68 months). Similar reports have been reported from Asian countries, and therefore they recommendedthat at least HCC patients with intrahepatic HVTT without PVTT could be suitable for liver resection [42; 43; 44]. For preventing intrahepatic recurrence, the usefulness of postoperative adjuvant TACE has been reported, and further evaluation with randomized trials are warranted [45].  
On the other hand, although IVCTT accounts for only 1% of all HCC cases, the prognosis of HCC patients with IVCTT is extremely poor because of the systemic circulation of the tumor cells and fatal complications such as pulmonary embolism, heart failure, and sudden cardiac death due to occlusion of the tricuspid valve [44]. Clinically, IVCTT is classified into three types according to its anatomic location relative to the heart for surgical guidance: type I, inferior hepatic (TT in the IVC below the diaphragm); type II, superior hepatic (TT in the IVC above the diaphragm, but still outside the RA); and type III, intracardiac (TT entering the RA) [46]. Most IVCTT can be pulled downward along with retracted liver and resected from the abdominal cavity because macroscopic thrombus of HCC is less likely to invade the vascular wall. On the other hand, in the type III IVCTT, if the TT lacks mobility and clamping of RA cannot be safely performed, cardiopulmonary bypass with median sternotomy is often required [47]. In addition, in cases with IVCTT invades the vascular wall, IVC resection and reconstruction along with liver resection has been reported to be safely performed by using an artificial graft. Therefore, surgery should be performed without hesitation [48; 49]. The significance of liver resection for the patients with IVCTT should be considered from the perspective of oncology and the prevention of sudden death. In the previous report by [PERSON] et al., hepatic resection for IVCTT was performed in 111 patients, with a MST of 17.8 months and a three-year survival rate of 33.1%, which was significantly better than the MST of 10.1 months and a three-year survival rate of 20.1% in the non-resection group (134 patients). However, in the non-resection group, there were few cases with effective systemic therapies such as Sorafenib and Atezolizumab + Bevasizumab. Therefore, careful assessment with further study is needed to evaluate the oncological benefit of liver resection. IVCTT can lead to pulmonary infarction, heart failure, and sudden death due to obstruction of the tricuspid valve. Therefore, even in cases where radical resection is difficult due to the presence of distant metastasis or multiple lesions in both lobes, liver resection and thrombectomy may be useful. [PERSON] et al. reported in a multicenter study that MST did not differ between patients who had resection with curative intent (18.7 months) and those with the residual tumor in the lung only (20.7 months) [47]. Therefore, a comprehensive evaluation of the disease state is necessary to determine the treatment plan.