# The Recent Development of the Surgical Treatment for Hepatocellular Carcinoma
## 5 Minimally Invasive Surgery for HCC  
Laparoscopic liver resection (LLR) was first reported in 1991, and since then, LLR has rapidly spread with an increasing number of reports about its feasibility, safety, and usefulness. Today, about a quarter of all liver resections in Japan were performed lapascopically [58]. In 2014, the second International consensus conference on Laparoscopic Liver Resection (ICCLLR) was held in Japan, and laparoscopic partial liver resection for HCC located the peripheral portion of the anterolateral segments of the liver was considered as standard clinical practice [59].  
The advantages of LLR can be summarized in four points: a good field of view with minimal disruption of the body wall, magnified vision, hemostasis by buffer effect of pneumoperitoneum, and preservation of portosystemic venous and lymphatic collaterals. The laparoscopic approach could provide a good field of view for surgery on the liver, which is located within the thorax without large incisions [60]. In addition, the magnification effect allows us to observe the fine vascular structures, and managing pneumoperitoneum pressure reduces bleeding from the hepatic veins, which enables more delicate surgical procedures with a dry surgical field [61]. However, if the pneumoperitoneum pressure is higher than the central venous pressure, the risk of pulmonary gas embolism increases [62]. In terms of short-term surgical outcomes, a recent meta-analysis comparing 4026 open liver resection (OLR) and 2786 LLR patients revealed that the R0 resection rate was comparable between the two groups and blood transfusion rate, hospital stay in days, 30-day mortality rate and morbidity were significantly lower in LLR compared to OLR [63]. Among the postoperative complications, superficial surgical site infections were reported to be significantly reduced in the LLR group [64]. In terms of long-term surgical outcomes, it has been reported that there may be no difference between the two groups; however, caution is required in interpretation due to the strong influence of background factors [63]. Other advantages include the possibility of reducing the frequency of postoperative complications such as ascites and liver failure by minimizing the transection of the ligament and liver mobilization [65]. In addition, postoperative adhesions are reduced after LLR, and LLR with its magnified view enables more careful dissection of adhesions strained by the pneumoperitoneum when performing repeat LLR. An additional possible advantage of repeat LLR is reported that complete adhesiolysis could be avoided when the adhesion does not affect the current operative procedure [66].  
However, it is still not a well-established procedure. It is essential to determine the indication based on a learning curve and preoperative evaluation of surgical difficulty to safely perform the operation. In 2014, [PERSON] et al. reported the Difficulty scoring system, which predicts the surgical difficulty of LLR based on five factors (tumor location, tumor size, tumor proximity to major vessels, the extent of liver resection, and liver function) [67; 68]. After that, this difficulty scoring system was revised after discussion at the Second ICCCLR and renamed the IWATE criteria [69; 70]. Although this scoring system could predict short-term surgical outcomes, the surgical difficulty assessment system is still not perfect, and various new difficulty assessment systems are even being proposed [71; 72; 73; 74].