**3.1. Surgical anatomy**

external beam radiation therapy in the form of stereotactic body radiation therapy (SBRT) or proton beam therapy (PBT), systemic targeted small molecule tyrosine kinase inhibitors, check-point inhibitor immunotherapy and investigational agents. These modalities are often

Surgical resection, or partial hepatectomy (PH), is a potentially curative surgical treatment option for up to 15–20% of patients with HCC. The primary objective of PH is to remove the HCC with an adequate margin, while preserving as much functional liver parenchyma to avoid post-resection hepatic failure. With improvements in preoperative assessment, patient selection, surgical and anesthetic techniques, intraoperative ultrasound, PH for HCC is now routine and safe. Operative mortality has been reduced to less than 5% with a 5-year overall

Several factors are considered in determining the eligibility for PH, including the patient's health status (e.g. age, ECOG PS), tumor-specific factors (e.g. extent and tumor biology), and the reserve of the liver remnant. Determined by the degree of liver dysfunction and the size of the postoperative liver remnant. While there is no strict age limit, one must consider the liver's regenerative capabilities in elderly patients, and the patient's ability to tolerate the physiologic consequences of portal pedicle clamping and acute hemorrhage on their cardiopulmonary system. In addition, patients undergoing a minimally invasive approach must also be able to endure the effects of the pneumoperitoneum and reverse Trendelenburg posi-

Several different clinical staging systems exist to stratify patients according to prognostic variables [4]. One of the most commonly used is the Barcelona Clinic Liver Cancer (BCLC) system which incorporates tumor size, number of nodules and hepatic function as classified by the Child-Pugh score [5]. The system classifies patients into early, intermediate, advanced and terminal stages and proposes recommended treatment strategy. According to this staging system, only stage 0 or early stage patients with small tumors are recommended for surgical

However, many view the BCLC criterion for resection to be restrictive. For patients with large tumors (beyond any down-staging or expanded OLT criteria) who are ineligible for OLT, PH is the only potentially curative treatment. With improvements in perioperative management, preoperative morphological assessment and manipulation of the future liver remnant, PH for large HCC has been safely performed with good oncologic outcome [6, 7]. Therefore, large tumor size alone is not a contraindication to PH, rather factors such as multiple or bilobar tumors, extrahepatic metastasis, involvement of the main bile duct, portal venous or other macroscopic vascular invasion, and portal hypertension are all relative contraindications to PH. When clinically not evident, portal hypertension can be evaluated by measuring the transjugular intrahepatic portosystemic gradient (PSG). PSG values greater than 10 mmHg are indicative of

significant portal hypertension and these patients must be approached with caution.

used together in a multidisciplinary approach.

**2. Preoperative considerations**

tioning on their physiology.

resection or liver transplant.

survival of 60–75%.

60 Liver Cancer

The surgical anatomy of the liver is based on Claude Couinaud's classification system and further refined in the Brisbane 2000 Terminology of Liver Anatomy and Resections (**Figure 1**) [22]. In this classification, the liver is divided into first, second and third order divisions based on internal anatomy rather than surface landmarks. First order division splits the liver into a right and left hemiliver along Cantlie's line, a plane extending from the middle of the gallbladder fossa to the center of the inferior vena cava. Second order divisions split the hemilivers into two respective sections or sectors, the medial and lateral sections/sectors on the left and anterior and posterior sections/sectors on the right. The third order division divides each section/sector into two segments, constituting the 9 individual hepatic segments defined by Couinaud. In general, each segment has a unique vascular inflow, outflow and biliary duct enabling segments to be removed without damage to other segments.

The liver is encapsulated by a fibrous capsule, known as Glisson's capsule. The capsule envelops the portal triads as they enter the liver parenchyma which makes it identifiable on intraoperative ultrasound. Furthermore, the dense capsule allows for control of the portal triad

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Some important perioperative anesthetic considerations should be accounted for to increase the safety of hepatectomy. To minimize the possibility of major intraoperative hemorrhage, the central venous pressure should be maintained at less than 5 mmHg to reduce the intrahepatic venous pressure. This is achieved using various anesthetic maneuvers and agents such as IVF restriction, and administration of isoflurane, fentanyl, mannitol, and cisatricurium. For open hepatectomy, the patient can be placed in slight reverse Trendelenburg position if pressures allow and switched to Trendelenburg position if there is significant hemorrhage with hemodynamic derangement to increase cardiac output and maintain end-organ perfusion. For laparoscopic/robotic hepatectomy, the patient is placed in reverse Trendelenburg position for a caudal approach which improves visualization of the vasculature, and the pneumoperitoneum creates a tamponade effect on the hepatic veins, which aids in limiting hemorrhage. Adequate vascular access should be obtained using large bore IVs, with appropriate invasive hemodynamic monitoring using A-line. Blood products should be readily available and resuscitation of operative blood loss should be with an appropriate combination of crystalloid, albumin and blood product as necessary. End-tidal CO<sup>2</sup>

embolism in the laparoscopic/robotic approach.

Resections are either "anatomic" or "non-anatomic". Anatomic resection defines a resection that obeys Brisbane divisions and is preferred for malignant disease because it has been found to lower rate of positive margins, decrease regional recurrences and improve surgical outcome. Non-anatomic resection refers to parenchymal transection that does not respect segmental planes and is typically used for debulking procedures, benign tumors or when trying to preserve remnant parenchyma. Achieving a microscopic margin negative (R0) resection is paramount to reducing local recurrence. 1 cm surgical margins have historically been

There are six standard, anatomic hepatic resections as defined by the Brisbane classification (**Figure 2**). Right hemi-hepatectomy consists of surgical resection of segments V-VIII and left hepatectomy includes segments II-IV and occasionally segment I. In an extended right hepatectomy or a right trisectionectomy/trisectorectomy, segments IV-VIII, and in an extended left hepatectomy or a left trisectionectomy, segments II-IV, V and VIII are resected. A left lateral sectorectomy involves resection of segments II-III and a right posterior sectionectomy includes segments VI-VII. Segmentectomies denote resection of any individual segment.

The common principle of anatomic hepatectomies involves parenchymal transection after both vascular inflow and outflow have been controlled. Given that each hepatic segment has

considered standard, but narrower margins have been safely demonstrated [23].

during dissection and enables pedicle ligation.

**3.2. Anesthetic considerations**

is measured to monitor for CO<sup>2</sup>

**4. Operative technique**

The proper hepatic artery and portal vein bifurcate prior to the hilum of the liver and form the right and left hepatic artery and portal vein which supply the right and left hemiliver. Joined by the biliary duct, the portal triad generally runs centrally within hepatic segments. The right hepatic artery enters the parenchyma soon after branching while the left has a longer extrahepatic course. In contrast, the three hepatic veins run between section/sectors in three portal scissurae. The right hepatic vein drains directly into the inferior vena cava (IVC) while the middle and left hepatic veins often form a common trunk prior to entering the IVC.

**Figure 1.** Schematic of liver anatomy separating the parenchyma into 9 anatomic segments. Each segment has unique blood supply and biliary drainage. Source: Cho, Fong. Hepatic Resection. In: Ashley SW, editor. Scientific American Surgery. Hamilton: Decker. 7th ed; 2014. pp. 1094–1114.

The liver is encapsulated by a fibrous capsule, known as Glisson's capsule. The capsule envelops the portal triads as they enter the liver parenchyma which makes it identifiable on intraoperative ultrasound. Furthermore, the dense capsule allows for control of the portal triad during dissection and enables pedicle ligation.
