Evaluation of New Classifications for Liver Surgery: Can Anatomic Granularity Predict Both Complexity and Outcomes of Hepatic Resection?

wo excellent articles in this issue of Annals of Surgery, by Jang et al and Kawaguchi et al, T provide a timely opportunity to revisit anatomic terms previously coined to describe hepatic resection planes and now used to predict various risks of hepatectomy. The terms ‘‘minor hepatectomy’’ and ‘‘major hepatectomy’’ were based on the partition of the liver along or beyond the Rex-Cantlie line. The terms were subsequently adopted to define the extent of resection and are now the basis for the Current Procedural Terminology coding and stratification for surgical outcome studies. The Brisbane 2000 classification has extended this paradigm by replacing the term ‘‘lobectomy’’ with the term ‘‘hemihepatectomy,’’ but ‘‘hemihepatectomy’’ is also inaccurate as the left liver typically accounts for only one-third, not half, of the total liver volume. As such, current anatomic classifications do not provide insight regarding surgical outcome. Do the new anatomic classifications proposed by Jang et al and Kawaguchi et al accurately predict the complexity and outcomes of hepatic surgical procedures? Jang et al analyzed 469 open and laparoscopic resections for hepatocellular carcinoma performed at Seoul National University for both surgical difficulty (time and blood loss) and postoperative outcomes (complications). The authors compared the low, medium, and high-complexity 19 procedures classification of Lee et al against the traditional minor hepatectomy/major hepatectomy classification, and found that the 3-tier classification predicted blood loss and operative time better than the 2-tier classification. However, the 3-tier complexity classification based on anatomic granularity did not perform better than the minor/major hepatectomy classification for predicting postoperative complications. Two major limitations, both of which the authors acknowledge, were the high blood loss during the learning curve of their experience and the limited number of high-complexity procedures (6.4% of their cohort). Kawaguchi et al analyzed operative time, blood loss, and conversion to laparotomy in 452 laparoscopic liver resections performed at the Institut Mutualiste Montsouris in Paris, and, on the basis of their findings, proposed classifying hepatectomies into 3 groups with different degrees of surgical complexity: group I, wedge resection and left lateral sectionectomy; group II, anterolateral segmentectomy and left hepatectomy; and group III, posterosuperior segmentectomy, right posterior sectionectomy, right hepatectomy, central hepatectomy, and extended hepatectomy. The analysis showed no differences between group I and group II patients in terms of rates of bile leak and major complications, both of which were minimal (0%–4%). In group III, which included large parenchymal transection surfaces and high-volume resections, the rate of bile leak was 11%, and the rate of major complications was 20%. Of note, right posterior sectionectomy, a ‘‘minor’’ hepatectomy by volume, was 1 of the most difficult laparoscopic resections, with the second highest median blood loss per procedure. One limitation of the study is that an average liver surgeon should not expect the excellent outcomes of Professor Gayet’s group (a laudable 5.5% transfusion rate and an extremely low 4.2% conversion rate, with almost all conversions among group III patients). We support the use of more detailed anatomic classifications such as those presented by Jang et al and Kawaguchi et al, but we believe that evaluation of the volume and quality of the liver remain equally important in the preoperative evaluation of surgical risk. The majority of posthepatectomy deaths are due to liver failure resulting from suboptimal quality of the future liver remnant. Notably, in Kawaguchi et al’s study, the highest rates of postoperative complications (bile leak, fluid collections, and liver failure) were observed in a subset of group III patients who underwent major or extended resections. Technical skills do not obviate the risks associated with greater anatomic extent of surgery in major/extended resections. The quality of the liver can best be defined using preoperative tests of function and regenerative capacity (indocyanine green