From Louisville to Morioka: where is now MILS?

It is my great honor and privilege to write an Editorial on this special issue of Updates in Surgery focused on “Minimally Invasive Liver Surgery: an up-to-date.” One of the Editors-in-Chief, Professor Fulvio Calise, kindly asked me to contribute to this issue. I know he has dedicated many efforts to promote the diffusion of minimally invasive liver surgery in Italy, including the foundation of the Italian Group of Minimally Invasive Liver Surgery (I Go MILS) with Professor Luca Aldrighetti (I Go MILS–President) and Professor Giulio Belli (I Go MILS—Vice President, It. Chapter IHPBA—President). Both are the Expert panels of the 2nd International Consensus Conference on Laparoscopic Liver Resection (ICCLLR) held on October 4–6, 2014, in Morioka, Iwate Prefecture, Japan. The ICCLLR in Morioka was held in an effort to better define the current role of laparoscopic liver resection (LLR) and to develop internationally accepted guidelines [1].

The organizing committee (Table 1) applied an independent jury-based consensus model to achieve this goal through analysis of the available literature with presentations including videos by Expert panels in front of Jury panels [2]. We all know that the level of evidence is low in the field of LLR to create strong recommendations. Therefore, we tried to be fair to draw the consensus statements under the judge by Jury. Table 1 shows the panels of the ICCLLR, and 43 respected surgeons, i.e., 34 expert panelists plus nine jury members not directly involved in LLR, were invited from 18 countries. Table 2 summarizes 17 clinical questions (CQs) related to the value and techniques of LLR, and 17 working groups assigned to answer these 17 questions by extensive literature reviews. The jury provided recommendations on CQ 1–7, which were related to benefits and risks of LLR [1]. However, the experts provided recommendations on CQ 8–17, which were related to technical aspects of LLR [1]. Expert consensus statements on CQ 8–17 were created from expert presentations, assessment of the literature, and experience on individual techniques.

Table 1 Invited panels of the 2nd International Consensus Conference on Laparoscopic Liver Resection (ICCLLR)

Table 2 Clinical questions for laparoscopic liver resection (LLR) and their working groups

One of the major achievements of the ICCLLR was that all international experts were present in the same room at the same time. These are technical recommendations from experts that will never be proved by level 1 evidence and still need to be shared so that the beginners can benefit from the expert learning curve. Another major achievement of the ICCLLR is publications of related activity to the ICCLLR [3–7] and the systematic reviews that were prepared to create recommendations before the ICCLLR [8–14]. A couple of more manuscripts are now under review to be published. A comprehensive literature review was performed, and analysis was done using multiple case series, case–control studies, reviews, and meta-analysis published over the last several years. It is our hope that all these publications from the ICCLLR will contribute to the steady and safe spread of LLR.

During the 6 years between the 1st International Consensus Conference on Laparoscopic Liver Resection in Louisville and the ICCLLR in Morioka, this comparatively new surgical technique has evolved and is rapidly being adopted worldwide (Table 3). In my opinion, LLR is superior to open liver resection (OLR) because the laparoscope allows better exposure with a magnified view, and the pneumoperitoneal pressure reduces hepatic vein bleeding from the cut surface [4]. The concept for liver resection has changed from the open ventral approach to the laparoscopic caudal approach. The important structures such as the hilar plate and the vena cava are clearly viewed just in front of you by the laparoscopic caudal approach. The better exposure with pneumoperitoneum is the main driving force that I began pure laparoscopic living donor hepatectomy based on our exerience of laparoscopy-assisted donor hepatectomy [15]. The most dangerous event that can happen during liver surgery is the injury of major vessels. As long as you see it clearly, you will never injure it without knowing it. The liver is located deep inside of the abdominal cavity surrounded by the rib bones. Because I am convinced that LLR is safer than OLR in my hand, I can offer this surgery to healthy donors where safety should be warranted most importantly.

Table 3 Evolutions in 6 years between two consensus conferences

During this 3-day conference, we extensively discussed how to improve the quality of LLR. Improving quality includes how to use energy devices [9], how to perform parenchymal transection [13], how to avoid bleeding [14], and how to perform parenchyma sparing anatomical resection. Complications in liver resection mainly consist of these three factors as shown in Table 4. Hepatic reserve should be estimated correctly to preserve remnant liver function. This must not be different ether in OLR and LLR. Meticulous transection and precise technique can be performed ether in OLR and LLR; however, the better exposure with a magnified view and the reduction in venous bleeding with pneumoperitoneum might be beneficial for these two factors.

Table 4 Complications in liver resection to be avoided

Because I was assigned to summarize benefits of anatomical resection at the ICCLLR, I proposed another new concept of parenchyma sparing anatomical (limited) resection. All anatomical resection can be performed from the hilar plate as described in Table 5. The caudal approach of LLR is beneficial to these limited anatomical resections from subsegmentectomy, segmentectomy, to sectionectomy [16, 17]. Parenchyma sparing resection is the key to preserve remnant liver volume and anatomical resection gives you clean resection not to leave non-perfused area of the liver. Therefore, parenchyma sparing anatomical resection is the future direction in liver surgery, and LLR will fit this direction perfectly. As we become aware of these essentials, LLR will be popularized more in the next several years.

Table 5 Parenchyma sparing anatomical resection to preserve remnant liver volume with clean margin

Finally, the most important message from the ICCLLR is to protect patients from this new surgical procedure. We recommended a broader-based registry because major LLR is still an innovative procedure although minor LLR is confirmed to be a standard practice in surgery. We are now in preparation of the registry worldwide. Furthermore, we proposed a scoring system to define the range of difficulty of LLR, similar to the Child–Pugh score, so that the beginner can start LLR easily and safely [7]. Selection of the appropriate patients according to the surgeon’s skills will eventually protect patients. In Japan, clustered mortality was sensationally reported in Japan just after the ICCLLR, which highlights the need for a safe introduction of major LLR [18]. The identification of difficult cases should be deferred depending on one’s individual learning curve of LLR.

In summary, the ICCLLR was very intense and successful. The judgment is a bit severe but the judgment is shared. We have to focus on more evidence, creation of registries, an implementation of master classes, and specific training. We discussed face to face our most up-to-date understanding, assessment of LLR, basic techniques, and its future directions. The future of LLR is in our hands. We certainly never imagined that we would come this far when the first LLR was reported.