It is generally accepted that surgical indications for hepatic metastasis of colorectal cancer include the following: (1) primary foci can be resected radically (R0); (2) hepatic metastatic foci can be resected and sufficient hepatic function can be preserved; if the hepatic metastatic foci and primary foci of colorectal cancer are to be resected separately at different stages, the volume of the residual liver should be ≥30 %; if the hepatic metastatic foci and primary foci of colorectal cancer are to be resected simultaneously, the volume of the residual liver should be ≥50 %; (3) the foci of extrahepatic metastasis can be resected or ablated; and (4) the patients have good cardiopulmonary function and can tolerate surgical treatment.

Surgical contraindications: uncontrollable extrahepatic lesion, e.g., unresectable primary foci, local recurrence of primary foci, peritoneum involvement, extensive lymphatic metastasis (lymphatic metastasis in the retroperitoneal region, mediastinum, or porta hepatis), or extensive pulmonary, bony, or central nervous system metastasis [3]. For patients with extrahepatic metastasis, hepatectomy can still be considered under the following conditions: pulmonary metastasis that can be resected or locally ablated; solitary extrahepatic lesions that can be resected or locally ablated, e.g., foci occurred in spleen or adrenal, or locally recurred foci; foci of hepatic metastasis can be resected although they directly invade ambient tissues, e.g., diaphragm or adrenal.

At present, the size, amount, and site of hepatic foci are no longer the factor restricting surgery. In a retrospective analysis on 131 patients with hepatic metastasis of colorectal cancer whose foci were resected, Imamura et al. [4] found that 5-year survival rates were 51 %, 46 %, and 25 %, respectively, for patients with 1–3, 4–9, and ≥10 foci. According to a multi-factor analysis, there was a significant difference in the survival time for the patients with ≥10 metastatic foci and those with one to three foci, but there was not any significant statistical difference in survival time for the patients with four to nine foci and those with one to three foci. Therefore, for patients with <10 metastatic foci, surgical resection is still suggested if the functional compensation can be achieved by residual livers.

For patients of colorectal cancer confirmed with hepatic metastasis, there was a dispute on selection of simultaneous resection or sequential surgery. In the 1990s, apprehensions about simultaneous resection included the following: (1) the incision for resection of colorectal cancer was different from that for hepatectomy; (2) resection of colorectal cancer might contaminate abdominal cavity, resulting in cross-sectional infection of the liver or subphrenic infection; and (3) simultaneous resection of colorectal cancer with hepatectomy might lead to a large operation wound and a higher morbidity and mortality rate. Therefore, generally, primary colorectal foci were resected first, and hepatectomy would be carried out after postoperative chemotherapy for 3–4 months.

In recent years, with the progress of postoperative treatment and operation technique, this conventional opinion has been changed. According to a retrospective study of Capussott et al. [5], the rates of morbidity, mortality, and anastomotic leakage were similar between the group of simultaneous resection and the group of sequential surgery; the operation time and the utilization ratio of red cell suspension and plasma for the group of simultaneous resection were more than that for the group of sequential surgery, but the hospitalization time for the group of sequential resection was longer than that for the group of simultaneous resection; a follow-up visit indicated that there was no difference in a 10-year survival rate. A similar result was obtained by Martin et al. [6] after a retrospective analysis on 230 patients treated with surgical resection against hepatic metastasis of colorectal cancer. The mortality rates of simultaneous resection and sequential resection were 2.2 % and 2.8 % respectively (P > 0.05). Peeters et al. [7] found that after resection of primary foci for patients with hepatic metastasis of colorectal cancer, the ratio of apoptosis to proliferation of cancer cells in hepatic metastatic foci was unbalanced, and the growth rate of tumor was speeded; therefore, they supported simultaneous resection. It is suggested in the Practice Parameters for Colon Cancer prepared by Standards Practice Task Force of the American Society of Colon and Rectal Surgeons [8] that: “If the hepatic metastatic foci can be resected completely and the incisal margin ≥1 cm; the incision is applicable to hepatectomy; the amount of the resected liver <50 %; the physical condition of patients allow the operation; the operator is skillful, they can be resected simultaneously.” At present, it is accepted that simultaneous resection of hepatic metastatic foci and primary foci are safe.

Preoperative evaluation involves the possibility of resection of hepatic and extrahepatic metastatic foci, the liver function, and the general body state. The evaluation of resectability of hepatic metastatic foci and extrahepatic metastatic foci depends mainly on imaging examination. Type B ultrasonic is preferred for hepatic metastatic foci. Contrast-enhanced CT is helpful for confirmation of lesion; detection of the size, amount, site of metastatic foci and the relation between metastatic foci and the bile duct and blood vessels in the liver; and measurement of volume of tumor, the part of the liver to be resected, and the residual liver. MRI has the advantage in detection of foci <1 cm; the enhanced MRI has a sensitivity of 80–90 % and a high specificity for detection of hepatic metastatic foci. PET/CT examination has an obvious advantage in sensitivity and specificity, which is helpful for detection of extrahepatic metastasis; moreover, it is the most correct method for staging of colorectal cancer in the progressive stage. Kong et al. [9] compared the detection results of PET/CT, contrast-enhanced CT, and enhanced MRI in foci of hepatic metastasis of colorectal cancer; in terms of each focus, the enhanced MRI could find out smaller metastatic foci, while PET/CT could find out more metastatic foci. With regard to the patients, the sensitivity and specificity of PET/CT and enhanced MRI both reached 98 and 100 %. In terms of detection of extrahepatic foci, PET/CT had an incomparable advantage over CT, which had changed the operation scheme for 17 % of patients. As neoadjuvant chemotherapy could lower the intake of 18F-fluorodeoxyglucose (18F-FDG) by hepatic metastatic foci, resulting in a lower sensitivity of PET/CT, it was suggested that PET/CT should be carried out before neoadjuvant chemotherapy [10, 11].

Few patients of hepatic metastasis of colorectal cancer are combined with hepatocirrhosis; although most of patients have good liver function, attention must be paid to the toxicity of chemotherapeutic drug to the liver. Vauthey et al. [12] reported that liver injury occurred to 22.7 % of patients receiving chemotherapy, for which the rate of liver failure and 90-day mortality increased; moreover, irinotecan was related to steatohepatitis. Rubbia-Brandt et al. [13] reported that oxaliplatin might lead to injury of sinus hepaticus. Therefore, before operation, evaluation should be carried out carefully on hepatic reserve function. Evaluation of hepatic reserve function includes (1) routine test of liver function, including serum bilirubin level, albumin level, leukocyte ratio, aminotransferase level, prealbumin level, and coagulation function test; it is generally accepted that, in terms of Child-Pugh score, patients of Class A have good tolerance to operation, while those of Class B are restricted to some extent, who could tolerate hepatolobectomy only after sufficient preoperative preparation; patients of Class C have bad tolerance to various operations, who should be restricted strictly. (2) Quantified hepatic reserve function test: at present, it is generally accepted that indocyanine green (ICG) excretive test is a sensitive index for estimation of hepatic reserve function; the ICG retention value at 15 min (ICGR-15) <20 % is the safety margin for hepatolobectomy; for those with ICGR15 of 20–29 %, the hepatic segmental resection can be carried out; for those with ICGR15 of 30–39 %, local resection can be carried out.

Selection of operation mode for hepatic metastasis of colorectal cancer depends on the size, amount, and site of metastatic foci, the relation of metastatic foci with blood vessels and the bile duct, and the liver function and the residual liver volume of patients. Besides preoperative evaluation, exploration during operation and application of iconography also play important roles in selection of operation mode. By means of ultrasonic exploration in operation, information can be obtained on distribution of metastatic foci in the liver and possibility of resection. Zacherl et al. [14] reported that the sensitivity of ultrasonic exploration during operation to metastatic hepatic carcinoma was up to 95.2 %, higher than 84.9 % of that of MRI, which changed the operation scheme of 22.8 % of patients. It was suggested that the probe should move along the surface of the liver slowly for carefully scanning section by section, which could avoid omission. During the scanning of the porta hepatis, attention should be paid as to whether or not abnormal resonance occurs in the main portal vein, its left and right branches, or the hepatic duct. During the scanning of the secondary porta hepatis, attention should be paid as to whether or not abnormal resonance occurs inside and along the hepatic vein and its branches. Finally, the size and border of tumor, the possible subfoci, and the anatomical relation of tumors with portal vein, hepatic duct and hepatic vein should be observed to determine the best margin of excision for tumors, which should not only comply with the principle of radical correction of tumors, but also be helpful for reservation of livers as much as possible. The portal vein, hepatic duct, and hepatic vein must be reserved; a scanning technique should be applied to determine the distance between their border and the tumor, the projection on hepatic surface, and their depth to hepatic surface, in order to avoid accidental injury during resection of liver parenchyma. In addition, during hepatectomy, especially hemihepatectomy, if there is any question on anatomical character of the bile duct, intraoperative cholangiography can be applied to determine the position of the bile duct and avoid injury.

The postoperative recurrence rate of hepatic metastasis of colorectal cancer is about 56.7 %, among which 36.4 % are intrahepatic recurrence [2]. Petrowsky et al. [20] reported a bicentric prospective study on 126 patients who received re-resection treatment due to recurrence after resection of hepatic metastatic foci of colorectal cancer; the 1-year, 3-year, and 5-year survival rates were 86 %, 51 %, and 34 %, respectively, similar to that of patients without recurrence after first resection of hepatic metastatic foci, while incidence of complications and mortality after operation were comparable to that after the first operation. Adam et al. [21] reported a follow-up study on 60 patients who received three times of the resection of hepatic metastatic foci; results indicated that the incidence of complication after operation was 25 %, and the 5-year survival rate was 32 %, significantly higher than those who did not receive surgery treatment after recurrence of hepatic metastatic foci after the second resection. However, because of adhesion, change of morphology and ratio of hepatic lobe due to hypertrophy of the residual liver, and change of the anatomical position of blood vessels and bile duct, the difficulty of re-resection after recurrence is significantly higher. Therefore, indications should be treated strictly; in principle, indications for re-resection are identical to that of the first resection. For patients recurred after operation, especially those who experience careful evaluation and have low tumor load, re-resection is applicable.

Open the hilar plate to reveal the branches of the left and right hepatic ducts. Incise peritoneum at the right side of the hepatoduodenal ligament to reveal the common bile duct and posterior portal vein. Resect bile cyst. Dissociate the right branch of the hepatic artery, which is usually located over the level of the cystic duct and behind the common hepatic duct, and then ligate it. The right branch of the posterior portal vein appears. Incise peritoneum behind the portal vein; dissociate the right branch of the portal vein slightly under direct viewing with the help of a curved clamp. Note: Do not injure the first branch of the right posterior branch, which goes downward and supplies the right half of the caudate lobe. It should be ligated and disconnected separately if the separation of the right branch of the portal vein is affected. Clamp with blunt-pointed straight blood vessel forceps, and disconnect the right branch of the portal vein. As the right branch of the portal vein is relatively short, simple ligation is not recommended in order to avoid a resultant narrow confluence. Close the residual end with a successive suture by 5-0 Prolene or Endo-GIA^TM stapler. If the anterior and posterior branches of the portal vein occur separately, they should be treated separately. After disconnection of the right branch of the portal vein, the border of the left and right part of the liver appeared.

Be careful during anatomizing the right hepatic duct, especially when the tumor is close to portal fissure. Opening omphaloschisis can reveal an anatomic character of the hepatic hilar region better. Sometimes the bile duct of the right front lobe or right back lobe merges into the confluence of the left and right hepatic ducts separately, or merges into the left hepatic duct, which should be identified carefully and disconnected separately. If the right hepatic duct cannot be identified, disconnection is not recommended, and the completeness should be maintained. As there are lots of varieties in the right hepatic duct, extrahepatic separation may lead to severe injury; our experience is that intrahepatic disconnection should be carried out when liver parenchyma is disconnected.

Intrahepatic vessel ligature technique is an alternative of extrahepatic anatomization of the porta hepatis, which is applicable especially when the tumor is far from the porta hepatis. As hepatic triads are coated with tough Glisson’s sheath, anatomize along the sheath to resect the portal triads, and ligate it. Thus, the separation time of the porta hepatis can be minimized, and the possibility that contralateral blood vessels and the bile duct are injured is decreased.

The right hepatic vein can be dissociated outside the liver, or treated inside the liver during separation of liver parenchyma. It is safer to treat the hepatic vein in liver parenchyma, while control of the right hepatic vein outside the liver may decrease the bleeding during disconnection of the liver and the massive hemorrhage during breakage of the vein. It is recommended to control the right hepatic vein outside the liver for giant tumors near the inferior vena cava. During anatomizing the right hepatic vein, the central venous pressure should be controlled to less than 5 mmHg, and Trendelenburg position of patients should be kept to avoid air embolus. Disconnect the hepatorenal ligament, right triangular ligament and right coronary ligament, and turn the right liver to the left; dissociate naked area, and push the adrenal gland away. If the adrenal gland contacts the liver closely, it is recommended to undermine upward along the loose gap between the right margin of the inferior vena cava and adrenal gland; thus, a tunnel is formed. Cut off with clamp, and ligate both ends and the suprarenal vein. Then the inferior vena cava appears. To dissociate the right hepatic vein, the venous ligament covering the inferior vena cava must be disconnected. If the venous ligament is thin, it can be cut directly. However, in most cases, it is thick, inside which there are blood vessels from the right posterior hepatic lobe to the inferior vena cava; therefore, it can be cut with clamp, and both ends should be sutured with 4-0 Prolene; alternatively, it can also be cut with Endo GIA to avoid massive hemorrhage. The anatomical gap between the right hepatic vein and the inferior vena cava will appear after cutting the venous ligament. Undermine along this gap, and go out of the gap between the liver and the right hepatic vein. If the gap is small and the separation is difficult to carry out, short hepatic veins should be cut and sutured upward stepwise, so that the front wall of the inferior vena cava will be dissociated completely, and the right hepatic vein will appear clearly. Disconnect the right hepatic vein with clamp, suture both ends with 4-0 Prolene, or disconnect with Endo GIA. During resection of the right lobe, it is unnecessary to control the middle hepatic vein outside of the liver.