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Page 2 of 15 Kato et al. Hepatoma Res 2021;7:10 I http://dx.doi.org/10.20517/2394-5079.2020.129

Keywords: Anatomic liver resection, Glissonian pedicle approach, hepatocellular carcinoma, laparoscopic liver
resection, Laennec’s capsule, robotic liver resection

INTRODUCTION
Robotic technology has increasingly infiltrated the field of abdominal surgery, encompassing urological,
[1,2]
gynecological, and upper and lower gastrointestinal procedures . However, the use of robotic systems
is still limited in hepatobiliary and pancreatic surgery, probably because of the technical difficulty and
insufficient instruments appropriate for this field. In particular, robotic liver resection (RLR) is still being
developed. Several authors have reported the surgical results of RLR, and most studies have described the
[3-6]
short-term results and compared them with those of conventional laparoscopic or open liver resections .
However, the feasibility, safety, and efficacy of RLR as a form of hepatobiliary surgery have not been well
defined.

Anatomic resection (AR) of the liver is a type of hepatectomy that results in accurate and complete
resection of an anatomic liver portion supplied by the corresponding portal vein branches. Therefore, AR
may offer high curability, particularly for hepatocellular carcinoma (HCC), which is characterized by portal
[7]
vein tumor invasion, even with small tumors . Several studies have suggested the oncologic advantages of
AR over non-anatomic liver resection (NAR) for patients with HCC . Therefore, AR is a recommended
[8,9]
form of resection for HCC in select patients, depending on their hepatic functional reserve. Although
recent advances in laparoscopic liver resection (LLR) have clearly established the feasibility and safety of
laparoscopic AR, it has been mostly performed by experts [10,11] . Furthermore, the feasibility and safety of
robotic AR remain unestablished [12,13] .

In this single-center study of RLR for HCC, we retrospectively reviewed the short-term and long-term
surgical outcomes of robotic AR and NAR performed in 57 cases in 46 patients. We describe these
outcomes here along with the technical details of our standardized methods of robotic AR.

METHODS
Definitions of anatomic liver resection and non-anatomic liver resection
We defined AR as a hepatectomy procedure during which an anatomic portion of the liver parenchyma
supplied by any of the first-order to fourth-order division portal vein branches is completely resected
without any remaining ischemic or congestive areas. Therefore, AR was defined to include segmentectomy
(I to VIII), sectionectomy (left lateral, medial, anterior, and posterior), hemihepatectomy, trisectionectomy,
and any type of extended procedure to completely resect the combined anatomic segments.
Subsegmentectomy, a type of resection of the specific liver areas supplied by the fourth-order division
branches of the segmental Glissonian pedicles, was also included as AR. Any liver resection procedures
other than AR were defined as NAR.

Robotic and laparoscopic liver resections at our institute
At our institution, we started our program of conventional LLR in May 2005 and that of RLR in December
2009. Between May 2005 and January 2020, we performed 492 minimally invasive liver resections (398 LLR
and 94 RLR). One hundred sixty-one of the 398 LLR (41%) and 46 of the 94 RLR (49%) performed were
AR. The 94 RLR were performed for 82 patients; 57 of the 94 RLR (61%) were performed for a total of 46
patients with HCC.

Patient selection
At our institution, minimally invasive liver resection, LLR or RLR, was the first choice of approach for
hepatic tumors that were 10 cm or smaller in size and for those that did not involve major vascular or