Survival after laparoscopic versus open resection for colorectal liver metastases

Laparoscopic liver surgery has become standard of care in many specialized centers worldwide (1,2). Despite its well-known advantages over open approach in surgical outcomes, the evidence supporting its advantages in long-term oncologic outcomes is limited.

We read with interest the recent meta-analysis by Nicholas L. Syn and colleagues, where they assessed the long-term oncologic outcomes of laparoscopic and open liver surgery for patients with colorectal cancer liver metastases (CRLM) (3). The meta-analysis includes 13 propensity-score matched studies and 2 randomized controlled trials with a total of 3,148 patients [laparoscopic (n=1,275), open (n=1,873)], and the authors report a survival benefit in favor of laparoscopic surgery. In two-stage meta-analysis including all studies the pooled hazard ratio was 0.87 (95% CI: 0.77–0.99, P=0.03). The authors concluded that the results of this meta-analysis demonstrated that laparoscopic liver surgery is at least not inferior to the standard open approach.

Most of the studies included in this meta-analysis were primarily aimed to investigate differences in surgical outcomes. Among 13 propensity score matched studies, only one study (4) used clinical risk score (5) as a covariate to achieve propensity score matching. Beppu et al. (6) used 5 variables from the clinical risk score in their propensity score matching, while four studies used 4 variables. The rest 7 studies included only 1 to 3 oncologically relevant variables in the matching process.

The 2 randomized trials included in the meta-analysis had postoperative complications as primary endpoint, while long-term oncologic outcomes were defined as secondary endpoints (7,8). These randomized trials were not designed to detect differences in survival rates.

Finally, this meta-analysis is an enhanced secondary analysis of survival data reconstructed from published Kaplan-Meier survival curves. This method was described by Guyot and colleagues in 2012 (9). They noted in their publication that this method is not quite the same as true individual patient data and has several limitations. The method was developed to for the analysis of large amount of RCTs reporting Kaplan-Meier curves. As one can observe, the current meta-analysis includes only 2 RCTs. Moreover, Guyot et al. noted that together with Kaplan-Meier curves, time-to-event outcomes, information on numbers at risk and total number of events are crucial when using this method, and if not provided, the algorithm may produce poor results. We found that not all studies in the current meta-analysis report this information. These shortcomings should be considered when interpreting the outcomes of the current meta-analysis.

We might conclude that this meta-analysis is well performed with advanced statistical analyses, and that it as such, improves the evidence-level of the current literature. However, most of the studies included, were not designed to detect survival differences. Our group has since 1998 been strong proponents for laparoscopic liver surgery. Considering the limitations of the included studies, we are reluctant to draw strong conclusions from the current meta-analysis with regards to oncologic outcomes. The body of evidence on laparoscopic liver resections should now be enriched by multicentre randomized trials and analyses of multicentre, multinational registries.

Acknowledgments

Funding: None.

Footnote

Provenance and Peer Review: This article was commissioned by the editorial office, Hepatobiliary Surgery and Nutrition. The article did not undergo external peer review.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://hbsn.amegroups.org/article/view/10.21037/hbsn-20-796/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Ciria R, Cherqui D, Geller DA, et al. Comparative Short-term Benefits of Laparoscopic Liver Resection: 9000 Cases and Climbing. Ann Surg 2016;263:761-77. [Crossref] [PubMed]
2. Abu Hilal M, Aldrighetti L, Dagher I, et al. The Southampton Consensus Guidelines for Laparoscopic Liver Surgery: From Indication to Implementation. Ann Surg 2018;268:11-8. [Crossref] [PubMed]
3. Syn NL, Kabir T, Koh YX, et al. Survival Advantage of Laparoscopic Versus Open Data From Randomized Trials and Propensity-score Matched Studies. Ann Surg 2020;272:253-65. [Crossref] [PubMed]
4. Cannon RM, Scoggins CR, Callender GG, et al. Laparoscopic versus open resection of hepatic colorectal metastases. Surgery 2012;152:567-73. [Crossref] [PubMed]
5. Fong Y, Fortner J, Sun RL, et al. Clinical score for predicting recurrence after hepatic resection for metastatic colorectal cancer: analysis of 1001 consecutive cases. Ann Surg 1999;230:309-18. [Crossref] [PubMed]
6. Beppu T, Wakabayashi G, Hasegawa K, et al. Long-term and perioperative outcomes of laparoscopic versus open liver resection for colorectal liver metastases with propensity score matching: a multi-institutional Japanese study. J Hepatobiliary Pancreat Sci 2015;22:711-20. [Crossref] [PubMed]
7. Fretland AA, Dagenborg VJ, Bjornelv GMW, et al. Laparoscopic Versus Open Resection for Colorectal Liver Metastases: The OSLO-COMET Randomized Controlled Trial. Ann Surg 2018;267:199-207. [Crossref] [PubMed]
8. Robles-Campos R, Lopez-Lopez V, Brusadin R, et al. Open versus minimally invasive liver surgery for colorectal liver metastases (LapOpHuva): a prospective randomized controlled trial. Surg Endosc 2019;33:3926-36. [Crossref] [PubMed]
9. Guyot P, Ades AE, Ouwens MJ, et al. Enhanced secondary analysis of survival data: reconstructing the data from published Kaplan-Meier survival curves. BMC Med Res Methodol 2012;12:9. [Crossref] [PubMed]