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Page 2 of 11 Sawa et al. Mini-invasive Surg 2024;8:30 https://dx.doi.org/10.20517/2574-1225.2024.43

complexity, 34.8% vs. 50.1%). However, the complication rate was steadily low and approximately 10% across all
complexity grades in the MISLR group.

Conclusion: Careful selection and gradual expansion of the indications of MISLR may facilitate improved
postoperative outcomes in patients undergoing highly complex MISLRs.

Keywords: Liver resection, laparoscopic liver resection, robot liver resection, the liver resection complexity
classification

INTRODUCTION
Liver resection is a potentially curative treatment for liver malignancies, including hepatocellular carcinoma,
[1-3]
intrahepatic cholangiocarcinoma, and liver metastases . Liver resection is performed via a laparotomy due
to its technical complexity for a laparoscopic approach. The liver is a blood-intensive organ, and
[4]
intraoperative bleeding may cause fatal complications . Postoperative complications such as bile leakage
are closely related to surgical manipulations, anesthesia, preoperative evaluation and preparation, and
postoperative observation and management . Recently, advancements in surgical instruments and
[5]
improved perioperative management have expanded the indications of minimally invasive liver resection
(MISLR) . Our group has gradually expanded the indications of MISLR to include technically less
[6-8]
demanding as well as technically complex procedures. Furthermore, the indications for MISLR have been
carefully selected to preserve the patient’s safety and improve the postoperative outcomes of MISLR when
compared with those of open liver resection (OLR). MISLR is reportedly associated with lesser blood loss,
lesser pain, and shorter hospital stays. However, no mortality and minimal complications should be
prioritized when selecting a new approach over the established approach (i.e., MISLR instead of OLR). We
hypothesized that our policy to gradually and carefully expand the indications for MISLR would not impair
the postoperative outcomes of patients undergoing technically complex MISLR procedures. Thus, to this
end, we aimed to assess the annual number of MISLRs performed and compare the outcomes of patients
undergoing MISLR with those of patients undergoing OLR, according to surgical complexity.

METHODS
Study population
A prospectively compiled database was searched for patients who had undergone liver resection at The
University of Tokyo from January 2011 to August 2023. Patients who had undergone liver resection in
addition to other procedures such as resection of other organs, cyst fenestration, and stoma closure and
patients who underwent associating liver partition with portal vein occlusion for staged hepatectomy, two-
stage liver resection, and laparoscopic-assisted liver resection were excluded. The study was approved by
The University of Tokyo’s Review Board (No: 2158-10; January 19, 2023).

Indications for MISLR
Our group started performing laparoscopic liver resection (LLR) in January 2009 and robot liver resection
(RLR) in December 2021. We categorized liver resection procedures using the liver resection complexity
classification which has been validated for both OLR and MISLR [Figure 1] [9-11] . We started performing LLR
in patients undergoing low-complexity liver resections such as wedge resection and left lateral
sectionectomy. Gradually, we expanded the indications of LLR to intermediate- and high-complexity liver
resections such as segmentectomy, sectionectomy, and hemi-hepatectomy. The indication of liver resection
and the selection of surgical approach (i.e., open vs. minimally invasive approach) were discussed in the
group meeting.