Laparoscopic Versus Open Liver Resection for Colorectal Liver Metastases—Which Is a More Suitable Standard Practice?
To our knowledge, a completed randomized controlled trial (RCT) comparing the efficacy of LLR and open liver resection (OLR) for patients with colorectal liver metastases (CRLM) has not yet been published. To date, only 3 studies have assessed the utility of LLR versus OLR using propensity score matching (PSM) analysis involving more than 100 CRLM patients treated by LLR.6–8 A well-designed PSM analysis can reduce selection bias of 2 procedures and can provide a similar reliable outcome of RCT;9 however, the results cannot be applied to all patients but are limited to selected patients. More recently, a meta-analysis of these PSM studies has been published.10 Large-scale PSM studies and this recent meta-analysis have demonstrated almost similar results: longer or similar operative time, reduced intraoperative blood loss or less transfusion requirement, shorter hospital stay, lower or comparable morbidity, and equivalent mortality in LLR patients compared with OLR patients.6–8,10
We congratulate Dr Fretland et al11 for publishing the first elegant the Oslo laparoscopic versus open liver resection for colorectal metastases (OSLO-COMET) RCT in this issue of Annals of Surgery. Their RCT was registered in ClinicalTrials.gov (NCT01516710) in January 2012.12 Another RCT comparing open versus laparoscopic left lateral liver sectionectomy (Orange II study; NCT00874224) was discontinued because of a delay in patient recruitment.13 The OSLO-COMET RCT is a single-center study in Oslo University Hospital with data collection performed from February 2012 to January 2016. Enrollment was limited to CRLM patients undergoing a parenchyma sparing minor liver resection, defined as a resection of less than three Couinaud segments. The authors who operated have an experience of more than 400 LLRs at the start of this study; therefore, they have sufficiently overcome the learning curve for minor LLR.14
Mortality, morbidity, and resection margins were the three principal comparators considered by the jury in the Morioka conference2 and were clearly resolved in this RCT. Mortality was low (0/133 in LLR and 1/147 in OLR) and comparable in the 2 groups. Morbidity (complication of Accordion grade 2 or higher)15 was a primary endpoint and was significantly lower in LLR than in OLR. Accordion grade 2 included complications that required pharmacological treatment, transfusion, or total parenteral nutrition. Major morbidity is usually defined as Accordion grade 3 or higher (Clavien-Dindo ≥ grade III) and is an indicator of poor survival in CRLM patients undergoing liver resection.15–17 Using this criterion of Clavien–Dindo ≥ grade III, morbidity was judged to be comparable (11% in LLR; 14% in OLR) in the 2 groups. It is essential to keep adequate resection margins for malignant disease; there have comparable percentages of involved resection margins on different surgical approaches (6% in LLR; 7% in OLR).
Although the amount of blood loss or transfusion rate was less in LLR than in OLR in all PSM studies,6–8,10 the difference in the amount was small but comparable to that in these RCT groups. LLR is thought to be superior to OLR because laparoscopy allows a better magnified view, and pneumoperitoneum reduces bleeding from low pressure vessels during liver transection.