Oncological Superiority of Right-sided Hepatectomy Over Left-sided Hepatectomy as Surgery for Perihilar Cholangiocarcinoma

Abstract

Right-sided hepatectomy, that is, right hemihepatectomy (H5678, according to the New World terminology)1 or trisectionectomy (H45678)1 is often preferentially used as the resection procedure for perihilar cholangiocarcinoma,2–4 so-called Klatskin tumor, for the following reasons. First, the right hepatic artery runs just behind the common hepatic duct near the porta hepatis. Second, right trisectionectomy is a more common and easier procedure, whereas left trisectionectomy (H23458)1 is demanding and rarely performed. Another reason is the anatomical consideration that the left hepatic duct is longer than the right hepatic duct.2–4 The first 2 reasons are reasonable, but the last one is doubtful. In 1989, Couinaud published a textbook on liver anatomy titled “Surgical anatomy of the liver revisited,”5 in which the length of the hepatic duct was not described. Ten years later, he again published a new book titled “Tell me more about liver anatomy”6 and briefly mentioned the length of the hepatic duct as follows: “the right hepatic duct is short (range, 1–24 mm; mean = 9.005 mm, n = 107) and missing in 46.72% of the cases in which the separate right lateral and right paramedian branches are replaced” (page 33); “the left hepatic duct length is 13.47 ± 1.67 mm when the right hepatic duct is single and 10.89 ± 1.92 mm when the right hepatic duct is duplicated” (page 73). Although this was the first report on the hepatic duct length, Couinaud did not show the definition of the hepatic duct; in other words, there was no description about where the length was measured. It may be very difficult to anatomically define the right or left hepatic duct due to various variations of biliary anatomy.5,6 From a surgical viewpoint, an important matter is not “the length of the extrahepatic portion of the hepatic duct” but rather “the length of the hepatic duct that can be resected.” In this regard, we measured the length of the resected proximal hepatic ducts in 475 patients who underwent major hepatectomy combined with caudate lobectomy for Klatskin tumors.7 In a right-sided hepatectomy, the length from the confluence of the right and left hepatic ducts to the cut end of the left lateral segmental bile duct was measured; in a left-sided hepatectomy, the length from the confluence to the cut end of the right posterior bile duct was measured.7 The length of the resected proximal hepatic duct was 14.1 ± 5.7 mm in left hemihepatectomy (n = 149), 14.9 ± 5.7 mm in right hemihepatectomy (n = 167), 21.3 ± 6.4 mm in left hepatic trisectionectomy (n = 122), and 25.1 ± 6.4 mm in anatomic, not conventional, right hepatic trisectionectomy7,8 (n = 37). In short, the length of the resected hepatic duct can be described as follows: (1) nearly equal between left and right hemihepatectomies (P = 0.626), (2) significantly shorter in right hemihepatectomy than in left hepatic trisectionectomy (P < 0.001), and (3) the longest in anatomic right hepatic trisectionectomy (vs left trisectionectomy, P < 0.005).7 We also measured the “estimated” lengths of the bile duct to be resected in the 4 types of hepatectomy using cholangiograms reconstructed from computed tomography images, taken before biliary drainage, in 61 patients with distal bile duct obstruction. The radiological measurements showed the similar trend to the above-mentioned surgical measurements.7 These observations should be carefully interpreted. Namely, our method of right hepatic trisectionectomy was “anatomic” trisectionectomy, in which the bile ducts of the left lateral sector were divided at the left side of the umbilical fissure.8 In “conventional” right hepatic trisectionectomy which is widely performed in most centers,2–4 the left hepatic duct is divided at the right side of the umbilical fissure which is achievable even in right hemihepatectomy. Overall, an assumption that “the left hepatic duct is longer than the right hepatic duct” lacks scientific validation and is simply the surgeons’ biased view. Considering abovementioned observations, the surgical procedure for Bismuth type IV tumors, particularly tumors with even extension, should be discussed. When liver function is stable and the estimated residual liver volume is sufficient, anatomic right hepatic trisectionectomy is recommended because this hepatectomy approach can provide the longest proximal ductal margin. When right trisectionectomy is deemed high risk, right hemihepatectomy or left trisectionectomy is the next best option. Considering that the resection volume is nearly equal between the 2 hepatectomy methods, the latter procedure is recommended if there is no vascular invasion, because it can offer a significantly longer ductal margin. Practically, the type of hepatectomy is determined by considering the predominant tumor location, the presence or absence of portal vein and/or hepatic artery invasion, the course of the portal vein or hepatic artery, and liver function. Surgeons must also consider that the right hepatic artery is sometimes involved in tumors behind the common hepatic duct. Nevertheless, the surgical strategy based on the previously mentioned biased assumption should be overhauled. In 1999, Neuhaus et al introduced the “no-touch technique,” that is, right-sided hepatectomy with routine portal vein resection for Klatskin tumors, and stressed the oncological superiority of this preemptive procedure.2,3 However, so far there have been no external validation studies showing the oncological superiority. More than 15 years ago, a Japanese center had adopted no-touch technique9 but stopped using this approach 8 years ago, due to disappointing oncological effects (personal communication with Professor Hirano from Hokkaido University). To the best of our knowledge, at present, no centers in Japan use the “no-touch technique.” Previously, we recommended right hemihepatectomy for Bismuth type I/II tumors,10 which are located inevitably near the right hepatic artery, for the following reasons: (1) reported survivals after limited local resection for Bismuth type I/II tumors were dismal due to the high incidence of R1 resection; and (2) right hemihepatectomy is simple without vascular resection. Although this concept is still deemed rational, Sugiura et al have shown that left hemihepatectomy with combined resection and reconstruction of the right hepatic artery is a valid alternative to right hemihepatectomy, especially in patients with an insufficient left liver functional reserve.11 We agree their concept because arterial reconstruction in left hemihepatectomy is relatively easy due to the short range involvement and large caliber of the distal artery, and we have also used this left side approach in such patients with Bismuth type I/II tumors. Finally, the surgical experiences at Nagoya University Hospital need to be briefly mentioned. Between 2001 and 2018, 787 patients underwent resection of Klatskin tumors, including with right trisectionectomy (n = 66, 8.3%), right hemihepatectomy (n = 247, 31.4%), left trisectionectomy (n = 198, 25.1%), left hemihepatectomy (n = 242, 30.7%), and other resection methods (n = 34, 4.3%).12 The 90-day mortality rate was 2.6% (8/313) for right-sided hepatectomy and 1.6% (7/440) for left-sided hepatectomy (P = 0.430). The incidence of positive proximal ductal margin was 11.2% (35/313) in right-sided hepatectomy and 11.6% (51/440) in left-sided hepatectomy (P = 0.862). The overall survival rate at 5 years (including all deaths) was 42% for right-sided hepatectomy and 39% for left-sided hepatectomy (P = 0.121), although the incidence of combined hepatic artery resection was significantly higher in left sided-hepatectomy than in right-sided hepatectomy (30.9% = 136/440 vs 2.9% = 9/313, P < 0.001).12 These results do not support the oncological superiority of right-sided hepatectomy over left-sided hepatectomy. If the resection procedure is flexibly selected, oncological sidedness may not be associated with the type of hepatectomy. Recent studies on the issue of right- or left-sided resections for Klatskin tumors reported a comparable long-term survival,13–16 although mortality was much higher in right-sided hepatectomy.14–16 Hepatobiliary surgeons should abandon the biased assumption that the left hepatic duct is longer than the right hepatic duct and should explode the fallacy that right-sided hepatectomy is oncologically superior. Hepatobiliary surgeons should make an effort to refine their surgical skills to safely and properly perform the demanding method of left hepatic trisectionectomy in which combined vascular resection is often required.12,17 This is a key to ensuring flexibility in the selection of a hepatectomy approach for Klatskin tumors, leading to expanded surgical indications and improved survival of this intractable disease. The most important aim is performance of decent resection with free margins, regardless of the type of hepatectomies.

Topics & Concepts