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Kato et al. Hepatoma Res 2021;7:10 I http://dx.doi.org/10.20517/2394-5079.2020.129 Page 11 of 15

Table 4. Major postoperative complications (≥ Clavien-Dindo grade IIIa)
C-D grade Number of events Details of events All (n = 57) AR (n = 23) NAR (n = 34)
IIIa 3 pleural effusion* 2 2 0
bile leak 1 0 1
IIIb 0 0 0 0
IVa 3 AKI* 2 2 0
cerebral infarction* 1 0 1
Vibe 1 ARDS and AKI* 1 1 0
V 0 0 0 0
Total 7 7 5 2

AR: anatomic resection; NAR: non-anatomic resection; C-D grade: Clavien-Dindo grade; AKI: acute kidney injury; ARDS: acute
respiratory distress syndrome. *defined as systemic complications

AKI nor pulmonary complications occurred in 21 cases after we stopped using the AirSeal system (ConMed)
and introduced our protocol involving intermittent pausing of pneumoperitoneum and concurrent lung
recruitment. The 90-day mortality and in-hospital mortality rates were 0% in both groups.

Survival data
The cumulative OS and DFS rates after the first RLR of 46 patients with HCC were analyzed. The OS
rates were 98, 82, and 74%, and the DFS rates were 80, 42, and 31% at 1, 3, and 5 years after the first RLR,
respectively [Figure 5]. The median OS rate was not reached. The median DFS length was 25.9 months after
surgery. For 21 HCC patients who underwent robotic AR as the first RLR, the OS rates were 95, 86, and
86%, and the DFS rates were 75, 37, and 37% at 1, 3, and 5 years after the first RLR, respectively [Figure 6].
For 25 HCC patients who underwent robotic NAR as the first RLR, the OS rates were 100, 81, and 71%, and
the DFS rates were 74, 41, and 29%, respectively, at 1, 3, and 5 years after the first RLR, respectively [Figure 6].
The OS and DFS rates were not statistically different between the AR and NAR groups (OS: P = 0.54; DFS:
P = 0.55; log-rank test).

DISCUSSION
This review evaluated the surgical results of 57 RLR cases that were composed of 46 HCC patients at
a single center over the course of the past 10 years. Furthermore, we described the particular surgical
techniques for robotic AR based on the extrahepatic GPA and HV root-at first one-way resection in detail.
We standardized AR using these two basic techniques for open liver resection and LLR [15,16] , and we were
able to apply the same techniques to the aforementioned 23 robotic AR cases. Additionally, the inherent
functional merits of robotics, including the instrument articulation and stabilized operative field, may have
contributed to precise hilar dissection during the extrahepatic GPA. However, insufficient instruments for
parenchymal dissection remain a problem. Harmonic shears (Intuitive Surgical) are useful for parenchymal
resection on a straightforward line such as that in hemihepatectomy, but they may be difficult to use or
require expertise in cases of a curved or complex resection plane, as in segmentectomies VII and VIII.
During such difficult AR procedures, we have to use the clamp-crush method with articulated forceps or
vessel sealers, which may frequently require the Pringle maneuver. Further development of instruments
suitable for parenchymal resection is required.

In our experience consisting of 94 RLRs, HCC was the indication for most procedures (n = 57; 61%).
Although the majority of HCC cases were relatively early-stage tumors (Union for International Cancer
Control stages I and II: 89%), the patient and tumor characteristics were not favorable; there were
considerable rates of underlying cirrhosis (54%), tumors located in laparoscopically difficult segments
(53%), repeat liver resections (37%), and concomitant extrahepatic procedures (14%). Nonetheless, the
overall (n = 57) postoperative short-term and long-term outcomes were considered acceptable compared
to the previously reported results of RLR for HCC or other types of tumors [3-6,13,18-22] . The operative time