In the provocative Surgical Perspective,1 “Oncological Superiority of Right-sided Hepatectomy Over Left-sided Hepatectomy as Surgery for Klatskin Tumor: Truth or Biased View,” Nagino et al put forth 2 concepts. The first is that there is no proof that the left hepatic bile duct is actually longer than the right hepatic bile duct. Sacrilege? They refer to Couinaud's report in cadavers (in a textbook that cannot be retrieved online) showing that the right hepatic duct averaged 9.0 mm (when there is not variant anatomy as occurs so often on the right) while the left averaged 13.5 mm. However, the authors claim that the technique of measurement was not well defined. It is difficult to imagine alternative definitions of the right and left hepatic bile ducts, especially by Couinaud who provided such detailed analyses of liver and biliary anatomy. Nagino et al refer to their retrospective paper2 published in 2015 on 475 resections for Klatskin tumors in which they routinely resected the segment I. They measured the distance from the edge of the transected bile duct to the hilar bifurcation (ie, the duct contralateral to the side of hepatectomy). For left hemi-hepatectomy plus segment I and bile duct resection (H1234-B in the New World Terminology3), the transected right duct measured 14.1 mm while for right hemi-hepatectomy plus segment I and bile duct resection (H15678-B) the left duct averaged 14.9 mm, which was not statistically different. Of course, the length of the transected duct may not have included the entire hepatic duct. Another confounding factor is that the contralateral duct would likely contract after being transected. Notably, there was no mention of the number of ducts requiring reconstruction. If the goal was to compare lengths of the right and left hepatic ducts, one could argue that it would have been better to measure the intact hepatic duct ipsilateral to the hepatic resection, which could be dissected ex vivo and measured precisely. An alternative approach to settle the issue would be to analyze magnetic resonance cholangiopancreatography (MRCP) or endoscopic retrograde cholangiopancreatography (ERCP) images. They previously performed a small analysis of cholangiograms reconstructed from CT images, which seems less desirable. Overall, their argument that the left hepatic bile duct is not longer is not convincing.
Regardless of the differential length of the hepatic bile ducts, the authors proclaim that the most relevant information for surgeons is how much duct can actually be resected. In other words, how far away can the surgeon get from a tumor at the bile duct bifurcation. For left trisectionectomy plus segment I and bile duct resection (H123458-B), biliary transection occurred at the right posterior sectoral duct. For right trisectionectomy plus segment I and bile duct resection (H145678-B), biliary transection occurred at a segmental duct in the left lateral section. The average resected length of the right biliary system was 21.3 mm versus 25.1 mm of the left biliary system. Thus, more of the biliary tree is “resectable” on the left than on the right, at least based on their transection technique of removing the entirety of segment IV.
Their second assertion is that right-sided liver resection is not oncologically superior over left-sided liver resection for hilar cholangiocarcinoma, which has been touted by some. More accurately, most surgeons prefer right trisectionectomy (H145678-B) over left trisectionectomy (H123458-B). Hence, the title of the second Perspective,4 “Extended Right Hemihepatectomy (H145678-B) is Preferred.” Lang and van Gulik thoroughly explain that this is because of the longer left portal vein and hepatic duct, lower likelihood of left hepatic artery involvement, surgeon familiarity with the procedure, and comparative technical ease. Oncologic outcome for hilar cholangiocarcinoma is predicated on margin status, nodal involvement, and other biologic factors of the tumor. The authors of both Perspectives agree there are no credible data that which side of the liver is removed matters in terms of tumor recurrence and long-term survival. In the subset with Bismuth type IV tumors with “even extension” bilaterally in which the liver volumes after trisectionectomy (H145678-B or H123458-B) would be comparable, the Japanese group favors “full” right trisectionectomy (H145678-B), presumably because of the greater “resectable” length of the left biliary system.
So what can we conclude? In terms of which side of the liver to remove, there is already enough dispute over the supremacy of being right or left handed, right or left brain dominant, and right or left politically bent. Hilar cholangiocarcinoma does not warrant being on the list in terms of oncologic outcome. Of course, there are some who believe that the optimal hepatectomy for a Klatskin tumor is right AND left. But we can save the role of liver transplantation for another time. Meanwhile, the left hepatic duct maintains its stature, awaiting another challenger in the future.
1. Nagino M, Ebata T, Mizuno T. Oncological superiority of right-sided hepatectomy over left-sided hepatectomy as surgery for perihilar cholangiocarcinoma: truth or biased view? Ann Surg
2. Hirose T, Igami T, Ebata T, et al. Surgical and radiological studies on the length of the hepatic ducts. World J Surg
3. Nagino M, DeMatteo R, Lang H, et al. Proposal of a new comprehensive notation for hepatectomy: the “New World” terminology. Ann Surg
4. Lang H, van Gulik TM. Extended right-hemihepatectomy is preferred. Ann Surg