# Study—International Multicentric Minimally Invasive Liver Resection (SIMMILR-5): A Comparison of Open, Conventional Laparoscopic and Tele-Robotic Laparoscopic Liver Resection for Hepatocellular Cancer

## TL;DR

This study compares open, conventional laparoscopic, and tele-robotic liver surgery for liver cancer, finding that laparoscopic methods offer better short-term outcomes than open surgery.

## Contribution

The study provides a large-scale international comparison of surgical techniques for hepatocellular cancer with rigorous adjustment for confounding factors.

## Key findings

- Conventional laparoscopy reduces blood loss, shortens surgery time, and decreases hospital stay compared to open surgery.
- Tele-robotic laparoscopy is safe but does not offer significant advantages over conventional laparoscopy.
- Short-term oncologic outcomes are comparable across all surgical approaches.

## Abstract

Surgery to remove liver tumors is an important treatment for hepatocellular cancer, but there is ongoing debate about which surgical technique provides the best outcomes. Traditional open surgery has long been considered the standard approach, while minimally invasive methods such as laparoscopy and robotic-assisted surgery have become increasingly common. However, it is still unclear whether these newer techniques provide meaningful advantages for patients. This international multicenter study compared open surgery, conventional laparoscopic surgery, and tele-robotic laparoscopic surgery in patients undergoing liver resection for hepatocellular cancer. By analyzing data from several high-volume surgical centers and adjusting for differences between patient groups, the study aimed to determine whether minimally invasive techniques improve short-term surgical outcomes. The findings suggest that minimally invasive surgery, particularly conventional laparoscopy, can reduce blood loss, shorten surgery time, and decrease hospital stay compared with open surgery, while robotic approaches appear safe but do not currently provide clear additional benefits.

Background: The role of minimally invasive surgery (MIS) for hepatocellular carcinoma (HCC) remains controversial because of concerns regarding oncologic adequacy, particularly margin status. While robotic-assisted hepatectomy has gained adoption, its true perioperative advantages over conventional laparoscopy and open surgery remain unclear. SIMMILR-5 was designed to evaluate the short-term outcomes of open, laparoscopic, and tele-robotic laparoscopic hepatectomy for HCC using rigorous adjustment for confounding. Methods: A retrospective international multicenter study was conducted including patients undergoing liver resection for HCC between June 2004 and November 2024 at five high-volume hepatobiliary centers. Surgical approaches included open (O), conventional laparoscopy (L), and tele-robotic laparoscopy (TRL). Propensity score matching was performed using demographic, clinical, and tumor-related variables. The primary endpoint was short-term mortality (30 and 90 days). Secondary outcomes included estimated blood loss (EBL), operative time, length of stay (LOS), R0 resection status, and major complications. Results: A total of 904 patients were identified (302 O, 568 L, 34 TRL). After matching, conventional laparoscopy was associated with significantly lower EBL, shorter operative time, and shorter LOS compared with open surgery (all p < 0.00001). Compared with open surgery, TRL was associated with lower EBL but no improvement in operative time or LOS. Compared with laparoscopy, TRL was associated with longer operative time and longer LOS. Short-term oncologic surrogates were comparable across approaches. Conclusions: Minimally invasive hepatectomy offers perioperative advantages over open surgery for selected patients with HCC, driven primarily by conventional laparoscopy. Tele-robotic hepatectomy is feasible and safe in experienced centers but does not demonstrate superiority over advanced laparoscopic techniques.