Chinese Medical Journal 2014;127(2):239-245:10.3760/cma.j.issn.0366-6999.20121215
Perioperative factors related to prognosis of regular hepatectomy in comparison with irregular hepatectomy

Feng Zhiqiang, Li Hongqi, Zhang Jinqian, Xu Lining, Xiao Mei, Huang Zhiqiang and Zhang Hongyi

Keywords
hepatectomy; perioperative procedures; prognosis
Abstract
Background The aim of this research was to analyze the perioperative factors of regular hepatectomy and irregular hepatectomy. The superiority of the clinical application of the two methods was compared in the perioperative period.
Methods From 1986 to 2011, 1798 patients underwent consecutive liver resections with regular hepatectomy and irregular hepatectomy at the Air Force General Hospital of People’s Liberation Army and the General Hospital of Chinese People’s Liberation Army. Their medical documentation was investigated retrospectively.
Results In patients on whom regular hepatectomy and irregular hepatectomy were performed, there was no significant difference in perioperative blood loss, complications, in-hospital mortality, hospital stay, and so on. But in regular hepatectomy, operating time was an independent risk factor (P <0.001, OR=1.004).
Conclusions There was no significant difference between the perioperative risk of regular hepatectomy and that of irregular hepatectomy.
In the mid-1950s, Goldsmith and Woodburne stressed that liver resection should strictly follow the anatomic characteristics of the liver, and therefore proposed the concept of regular hepatectomy (regular hepatic lobectomy), also known as anatomical liver resection (anatomical hepatectomy). Until now, regular and irregular hepatectomy are still controversial in their respective scopes of applications and advantages.1-12
Several series of laparoscopic liver resections had been reported, and these series had shown the feasibility of resections. After a long training with limited liver resection in superficial segments, laparoscopic anatomical minor, and major resections are feasible. It reduced loss of blood and hospital stay. Intrahepatic Glissonian approach facilitated laparoscopic liver resection and may increase the development of laparoscopic liver resections.13-17This study reviews 1798 cases of simple hepatectomy at the Air Force General Hospital and the General Hospital of Chinese People’s Liberation Army (PLA), for the purpose of clarifying the advantages of regular hepatectomy and irregular hepatectomy.
METHODS
Patient selection and review of medical history
We retrospectively reviewed the medical records of 1798 consecutive patients who underwent curative resection for hepatocellular carcinom (HCC) between January 1986 and February 2011 in the Air Force General Hospital of PLA and the General Hospital of Chinese PLA with simple hepatectomy, including 1223 cases of irregular hepatectomy and 575 cases of regular hepatectomy. All patients whose pre-operative radiologic evaluation was performed with a three-phase dynamic enhanced multi-detector CT (MDCT, BD, USA) scan within 1 month before surgery; patients whose tumor pathology was pure hepatocellular carcinoma, for example combined hepatocellular-cholangiocarcinoma; and patients who completed the 6-month follow-up period were included. Alpha-fetoprotein level (AFP) and protein induced by vitamin K absence-II (PIVKA-II) levels were recorded if blood samples obtained within a month before surgery were available.
Pre-operative assessment
All patients were evaluated preoperatively by physical examination; serum laboratory tests including liver function tests and hepatitis B and C virus serology were carried out as appropriate. Status of the non-tumorous liver parenchyma was defined according to the classification of Knodell et al by pre-operative liver biopsy. Pre-operative decision-making to consider the liver hanging maneuver was based on tumor location assessed by triphasic computed tomography (CT, BD, USA). Special attention was given to assess the state of inferior vena cava (IVC) from the level of hepato-caval confluence to the right renal vein. Direct invasion of tumors to distal major hepatic veins, the diaphragm, retroperitoneum, or tumor contact with IVC except the avascular space was not considered as contraindication to perform the hanging maneuver. Even though initial assessment shows tumor infiltration to the anterior surface of IVC, tumor regression induced by systemic chemotherapy making the retrohepatic space free of tumor enables considering the hanging maneuver.
CT image acquisition
Pre-operative CT images were obtained by one of the following commercially available MDCT scanners; 4, 16, and 64 channel MDCT scanners (Somatom Plus 40, Sensation 16, and Sensation 64, Siemens Medical Systems, Erlangen, Germany). Each patient was injected with 120–150 ml of iobitridol (Xenetix 300; Guerbet, Aulnay-sous-Bois, France) or iohexol (Omnipaque 300; Daiichi Pharmaceutical, Tokyo, Japan) through an 18-gauge venous cannula placed at the antecubital fossa for contrast injection, using a mechanical injector with a fixed duration of 30 seconds. After unenhanced images were obtained, dynamic three-phase imaging was performed. The hepatic arterial, portal venous, and delayed phases were scanned at 15, 40, and 180 seconds, respectively, after the aorta reached 100 HU.
Pre-operative CT finding analysis
The pre-operative CT scan of each patient was reviewed by a gastrointestinal radiologist with 8 years of experience in hepatobiliary imaging. No clinical, laboratory, or pathology information other than the presence of HCC was provided during image analysis. The tumor’s size (the longest diameter on the axial plane), shape, capsule, and margin were evaluated. Tumor shape was classified into four categories: nodular (round in shape with size less than 5 cm), massive expanding (round in shape with size equal to or greater than 5 cm), multinodular confluent or infiltrative type. Tumor capsule integrity was assessed on a five-point scale according to the percentage of the tumor surface covered by the capsule (grade 1: covering more than 75%, grade 2: covering 51%–75%, grade 3: covering 26%–50%, grade 4: covering no more than 25% or absent capsule, and grade 5: could not be evaluated because of complete necrosis). The number of identifiable tumor lesions that appeared to be hyperdense on the arterial phase and washed out on equilibrium phase images was counted. Portal vein thrombosis was considered to be present if a filling defect in the portal vein was observed at the portal phase of contrast enhancement.
Surgical pathology parameters
The surgical pathology report for each patient was reviewed; and features including the presence or absence of portal tumor thrombi, microscopic vessel invasion, tumor capsule formation, and the success or failure of obtaining a tumor-free surgical resection margin were recorded. The degree of tumor differentiation was categorized according to the Edmondson-Steiner classification as low-grade (Edmondson-Steiner grade Iand II) and high-grade tumor (Edmondson-Steiner III and IV). Tumor differentiation couldnot be assessed in 39 patients because of extensive necrosis of the tumor, and these patients were recorded as having missing data. The extent of tumor necrosis reported by the pathologist was recorded; we considered necrosis of 95% or more of the entire tumor as nearly total necrosis and classified each patient either in the group of nearly total necrosis (≥95% necrosis of the whole tumor) or the low necrosis group (<95% necrosis of the whole tumor). The physical relation of the tumor with the Glisson’s capsule was categorized according to a three-point scale (grade 1: tumor separated from the Glisson’s capsule by normal liver parenchyma; grade 2: direct contact of tumor with the Glisson’s capsule without microscopic evidence of tumor penetration; and grade 3: microscopic evidence of tumor penetrating the Glisson’s capsule).
Follow-up after surgery
Patients were regularly followed up with dynamic CT scans and serum tumor markers (AFP and/or PIVKA-II) at 3–6 months after surgery using additional liver MRI, conventional angiography, and/or ultrasound if necessary. Early recurrence was defined as tumor recurrence identified within 6 months after surgery. Postoperative HCC recurrence was considered to be present if either a focal lesion was identified measuring at least 2 cm with arterial hypervascularization which was demonstrated in at least two imaging modalities, or a hypervascular nodule exceeding 2 cm was noted in a single imaging study in the presence of over 400 ng/ml AFP.
In addition, any new nodule that had appeared during the follow-up period, exceeding 2 cm in size, or a newly appearing nodule showing contrast washout leading to hypoattenuation in the equilibrium phase was considered to be highly suspicious for HCC recurrence regardless of size and was confirmed with supplemental biopsy or short-term follow-up CT or MRI.
Statistical methods
Data were obtained retrospectively by reviewing and sorting out the medical records of 1798 cases. Continuous variables were presented as mean ± standard deviation (SD). Analysis of variance (ANOVA) ort-test was used for between-group comparisons of the data if normally distributed. Kruskal-Wallis test was used if the data were not normally distributed. Theχ2test was used when necessary for categorical data. Correlation between variables was assessed using Spearman’s non-parametric correlation analysis. Logistic regression was used to evaluate the association between style of resection and those specified potential predictive factors. SPSS version 13.0 (SPSS Inc., Chicago, IL, USA) was used for all statistical analysis.P<0.05 (two-sided) was deemed statistically significant.
RESULTS
Resection area of regular hepatectomy and irregular hepatectomy
The diagnoses of malignant diseases and benign diseases are shown in Tables 1 and 2. Resection of the left lateral lobe formed the majority, followed by resection of the left half and the right half livers. There were also a few cases of right tri-lobe resection and life tri-lobe resection (Table 3). Table 4 gives details of the majority of the cases that involved the resection of liver segments.
Relationship of operative and perioperative factors with the style of resection
In all patients in this study, the rate of cases with ultrasound in-line irregular resections was significantly higher than those in regular resections (P<0.001). HBsAg positive/HBsAg negative patients with irregular resections were significantly higher than those with regular resections (P<0.001). HCV Ab positive/HCV Ab negative patients with irregular resections were significantly higher than those with regular resections (P=0.014). It was significantly higher in cases of malignant neoplasm/benign neoplasm than those in regular resections (P<0.001), and was also significantly higher in cases of less than three resected liver segments/more than three resected liver segments than those in regular resections (P<0.001). The size of the largest tumor was significantly larger in regular resections than in irregular resections (P<0.001). The above situation was just the opposite in cases of regular resections (Tables 5 and 6).
Factors associated with the method of resection
Multivariate analysis shows that the operating time of regular hepatectomy was significantly longer than that of irregular hepatectomy (P<0.001). There was no statistical significance for some perioperative factors, i.e. occurrence of complications and blood loss (Tables 7–10).
DISCUSSION
Hepatic surgery is actually the combination of surgical operation and hepatic anatomy. It has been evolving rapidly after hepatic anatomical structures were known by surgeons.18Besides, extended hepatectomy would not contribute to promoting the long-term survival rate for patients with intermediate-stage and advanced hepatocellular carcinoma. With intensifying knowledge of the physiological functions of the liver and advancement in and accumulation of experience in hepatic surgical techniques, operative mortality rate and complication rate in hepatectomy cases with normal and non-cirrhotic liver conditions were significantly lowered in 1980s, making hepatectomy a relatively safe operation to a certain extent.19-22
As the operation became safer, indications and scopes for hepatectomy were widened, and surgical resections were performed more on patients with benign hepatic lesions or liver metastases.23` Nevertheless, previous studies had never reached a consensus in relation to the adoption of regular or irregular hepatectomy in the treatment of different hepatic lesions. Vyhnánek performed non-anatomical wedge resections in 47 cases with metastatic liver cancer with a focus that was less than 2 cm in diameter and the surgical margins of four cases were subsequently proved by pathology.24-26Cho et al analyzed 168 cases with hepatocellular carcinoma having a diameter less than 5 cm, including 99 cases of anatomical hepatectomy and 69 cases of non-anatomical hepatectomy, and multivariate analysis showed that the former was superior to the latter in the overall survival rate and recurrence-free survival rate.27
Eguchi et alanalyzed 5781 cases with solitary liver cancer from 1994 to 2001 throughout Japan, of which 2267 cases underwent anatomical hepatectomy and 3514 cases underwent non-anatomical hepatectomy. The results of the analysis indicated that the 5-year survival rate of the former was higher than that of the latter, though this difference was particularly obvious in cases of liver cancer of 2–5 cm in diameter.28Suh studied 119 cases with liver cancer less than 5 cm in diameter by hepatectomy in Korea, including 74 cases of anatomical resections and 45 cases of non-anatomical resections. Consequently, though the complication rate for the latter was higher than that of the former (33.3% vs. 27.0%), it was of no statistical significance, and there was no difference in the recurrence-free survival rate and overall survival rate for the above two kinds of hepatectomy.29Li et al summarized 120 cases of hepatectomy for liver cancer from 1964 to 1985, of which seven cases underwent regular hepatectomy and 113 underwent irregular hepatectomy. Li’s research showed that there was no difference in the prognosis between irregular hepatectomy and regular hepatectomy in the treatment of liver cancer, but the complication rate, mortality rate, blood loss and operating time for the former were all lower or less than the latter. Li et al believed that it was more common for Asian patients to suffer from primary liver cancer together with cirrhosis and therefore, irregular hepatectomy was more desirable.30Zhou et al analyzed 1000 cases of hepatectomy for liver cancer of less than 5 cm in diameter, and the results indicated that there was no difference in the survival rate for local resections (949 cases) and hepatic lobectomies (51 cases), but the former would increase resectability rate and lower operative mortality rate.31
To summarize, methods of hepatectomy for small hepatocellular carcinoma vary in different medical literature. In China, irregular hepatectomy is adopted more commonly to retain more liver parenchyma, since HCC of most people in China is HBsAg positive and an overwhelming majority of patients who undergo hepatectomy also suffer from cirrhosis. Therefore, more functional liver tissues should be retained in such cases of hepatectomy. In surgeries for large hepatocellular carcinoma, anatomical lobectomy, segmentectomy or hemihepatectomy is usually the only choice, as the carcinoma(s) has/have occupied a whole lobe, segment or half of the liver, whereas enucleation that can preserve more liver parenchyma is more often adopted for hepatectomy in the treatment of benign solid liver tumors, which do not involve the spread of tumor cells in the liver.32However, in cases involving lesions of the biliary system, such as intrahepatic bile duct stone and intrahepatic bile duct stricture, regular hepatic segmentectomy should be adopted and the structure of the biliary tree in liver segments should be followed strictly, so as to resect radically the bile duct lesions, preserve the healthy liver tissues and reduce the occurrence of complications such as residual stones, biliary fistulas, infections and abscess.33,34
Our study reviewed consecutive cases of simple regular and irregular hepatectomy performed at the Air Force General Hospital of PLA and the General Hospital of Chinese PLA for more than two decades from 1986 to 2011 and made a retrospective analysis of multiple perioperative factors (Tables 1 and 2). The results showed that, there was no difference in operative blood loss, post-operative complications, in-hospital mortality and postoperative hospital stay between regular hepatectomy and irregular hepatectomy, but the operating time for regular hepatectomy was significantly longer than that for irregular hepatectomy (P<0.001,OR=1.004; Tables 3–6).
Our study indicated that regular hepatectomy took a longer operating time than irregular hepatectomy, while there was no significant difference in other perioperative risk factors between the two types of surgeries (Table 7). The reason for this may be summarized as follows: with intensifying knowledge about liver hemorrhage and advanced hemostatic techniques in the recent years, hepatic surgeries and vascular surgeries have become more elaborate, while surgical techniques of regular and irregular hepatectomy become increasingly mature. Therefore the outcome of both surgeries is less differentiated (Table 8). Meanwhile, irregular hepatectomy in the Department of Hepatobiliary Surgery of the Air Force General Hospital of PLA and the General Hospital of Chinese PLA is more than just simple and crude “excavation”, and instead, the lesion focus should be resected accurately. In a word, irregular hepatectomy should also be as precise as possible (Tables 9 and 10).
In addition, as the results of this study showed that regular hepatectomy was equally safe compared with irregular hepatectomy, this study would prove to be powerful support for regular hepatectomy in liver resections for living donor liver transplantations (regular hepatectomy is usually adopted in such operations, for the resected liver portion must have regular and clear fracture surfaces, which will contribute to successful surgical operations such as inosculation between the donor liver and recipient liver). For ordinary hepatic surgeries, irregular hepatectomy is acceptable. For example, in most cases of hepatic hemangioma resections in the Air Force General Hospital of PLA and the General Hospital of Chinese PLA, enucleation of the hemangiomas was performed under hepatic vascular exclusion. It is worth mentioning that this study did not include the long-term effects of regular hepatectomy and irregular hepatectomy; so further follow-up visits and researches are needed to reach any conclusion about the effects of both kinds of surgeries in the treatment of malignant tumors.
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(Received February 28, 2013)
Edited by Hao Xiuyuan.
Table 1.Diagnoses of malignant diseases
Diagnoses n(%)
Primary liver cancer 860 (84.4)
Metastatic hepatic carcinoma 116 (11.4)
Canceration of benign diseases* 8 (7.9)
Hepatic cystadenocarcinoma 6 (5.9)
Hepatoblastoma 5 (4.9)
Hepatic non-Hodgkin lymphoma 3 (2.9)
Hepatic sarcoma 3 (2.9)
Hepatic malignant fibrous histiocytoma 3 (2.9)
Hepatic neuroendocrine carcinoma 2 (2.0)
Hepatic angiosarcoma 2 (2.0)
Others† 11 (10.8)
Total 1019 (100.0%)
*Hepatic cystoadenoma (3 cases), Caroli’s disease (2), hepatic adenoma (2), hepatic fibroma (1).†Intrahepatic bile duct lymphoma mucosa associated lymphoid tissue (1 case), hepatic malignant schwannoma (1), extrahepatic bile duct embryonal rhabdomyosarcoma (1), hepatic undifferentiated embryonic sarcoma (1), hepatocellular liver cancer coexisting with other organ malignant tumor (7).
Table 2.Diagnoses of benign diseases
Diagnoses n(%)
Hepatic hemangioma 319 (40.9)
Hepatolithiasis 241 (30.9)
Hepatic cyst 21 (2.7)
FNH 35 (4.5)
Intrahepatic bile duct stricture 17 (2.2)
Hepatic adenoma 16 (2.1)
Hepatic angioleiomyolipoma 16 (2.1)
Hepatic echinococcosis 9 (1.2)
Hepatic inflammatory pseudotumor 13 (1.7)
Hepatic trauma 11 (1.4)
Caroli’s disease 10 (1.3)
Other inflammation lesion* 10 (1.3)
Hepatic cystoadenoma 7 (0.9)
Hepatic atypical hyperplasia 4 (0.5)
Hepatic parasitosis† 4 (0.5)
Hepatic phthisis 4 (0.5)
Hepatic granuloma 4 (0.5)
Hepatic spontaneous hematoma 4 (0.5)
Hepatic hamartoma 3 (0.4)
Hepatic abscess 3 (0.4)
Others‡ 28 (3.6)
Total 779 (100.0%)
*Focal necrosis of liver (3 cases), hepatic calcification (1), mycotic granuloma of liver (1), sclerosing cholangitis (1), other (4).†Distomatosis hepatic.‡Chronic cholecystitis (6), nodular cirrhosis (4),hemangioma coexists with intrahepatic bile duct stone (1), peliosis hepatic (1), hepatic liparomphalus (1), hepatic adenomatous hyperplasia (1), hepatic fibroid (1), hepatic leiomyoma (1), others (6). Unable to exclude malignancy in cases of cholecystitis and nodular cirrhosis.
Table 3.The liver resection area of regular hepatectomy
Area n(%)
Section II 5 (0.9)
Section III 8 (1.4)
Section IV 13 (2.3)
Section V 14 (2.4)
Section VI 17 (3.0)
Section VII 6 (1.0)
Section VIII 5 (0.9)
Section I 3 (0.5)
Right half liver 93 (16.2)
Right posterior lobe 18 (3.1)
Right anterior lobe 6 (1.0)
Right tri-lobe 9 (1.6)
Left half liver 152 (26.4)
Left tri-lobe 4 (0.7)
Left lateral lobe 225 (39.1)
Total* 575 (100.0%)
*The lesion may be multiple and discontinuous.
Table 4.The liver resection area of irregular hepatectomy
Area n(%)
Section II 8 (0.7)
Section III 20 (1.6)
Section IV 133 (10.9)
Section V 92 (7.5)
Section VI 98 (8.0)
Section VII 94 (7.7)
Section VIII 63 (5.2)
Section I 32 (2.6)
Extended right half liver 7 (0.6)
Extended left half liver 10 (0.8)
Widespread and multiple* 4 (0.3)
Right half liver 205 (16.8)
Right posterior lobe 216 (17.7)
Right anterior lobe 111 (9.1)
Middle liver 19 (1.6)
Left half liver 130 (10.6)
Left lateral lobe 138 (11.3)
Total† 1223 (100.0%)
*The lesion may be widespread and multiple and may lie in every lobe of the liver.†The lesion may be multiple and discontinuous.
Table 5.Univariate analysis of factors associated with style of resection (categorical data)
Variables Regular (n(%)) Irregular (n(%)) Pvalues*
Gender
Male
Female
 
312 (54.3)
263 (45.7)
 
844 (69.0)
379 (31.0)
 
<0.001
Previousanatomical surgery
No
Yes
 
458 (79.7)
117 (20.3)
 
1031 (84.3)
192 (15.7)
 
0.015
Repeat resection
No
Yes
 
570 (99.1)
5 (0.9)
 
1213 (99.2)
10 (0.8)
 
1.000
Laparoscopic resection
No
Yes
 
549 (95.5)
26 (4.5)
 
1172 (95.8)
51 (4.2)
 
0.731
Ultrasound in-line resection
No
Yes
 
539 (93.8)
36 (6.2)
 
1038 (84.9)
185 (15.1)
 
<0.001
Transfusion (all)
No
Yes
 
297 (51.7)
278 (48.3)
 
677 (55.4)
546 (44.6)
 
0.142
Transfusion (blood product)
No
Yes
 
309 (53.7)
266 (46.3)
 
700 (57.2)
523 (42.8)
 
0.163
Transfusion (autoblood)
No
Yes
 
545 (94.8)
30 (5.2)
 
1179 (96.4)
44 (3.6)
 
0.107
Child-Pugh
A
B or C
 
561 (97.6)
14 (2.4)
 
1197 (97.9)
26 (2.1)
 
0.062
HBsAg
Negative
Positive
 
422 (73.4)
153 (26.6)
 
604 (49.4)
619 (50.6)
 
<0.001
HCV Ab
Negative
Positive
 
568 (98.8)
7 (1.2)
 
1189 (97.2)
34 (2.8)
 
0.014
Pathology
Malignant
Benign
 
247 (43.0)
328 (57.0)
 
778 (63.6)
445 (36.4)
 
<0.001
Incisal margin
Residual
No residual
 
5 (0.9)
570 (99.1)
 
8 (0.7)
1215 (99.3)
 
0.838
Number
Single
Multiple
 
488 (84.9)
87 (15.1)
 
990 (80.9)
233 (19.1)
 
0.451
Lymph node dissection
No
Yes
 
573 (99.7)
2 (0.3)
 
1219 (99.7)
4 (0.3)
 
1.000
Major organ resection
No
Yes
 
573 (99.7)
2 (0.3)
 
1204 (98.4)
19 (1.6)
 
0.965
≥3 segments resected
No
Yes
 
314 (54.6)
261 (45.4)
 
794 (64.9)
429 (35.1)
 
<0.001
Blood loss
<1000 mL
≥1000 mL
 
501 (87.1)
74 (12.9)
 
1090 (89.1)
133 (10.9)
 
0.216
Complication
No
Yes
 
495 (86.1)
80 (13.9)
 
1058 (86.5)
165 (13.5)
 
0.808
Mortality
No
Yes
 
574 (99.8)
1 (0.2)
 
1215 (99.3)
8 (0.7)
 
0.323
2test.
Table 6.Univariate analysis of factors associated with style of resection (numeric data)
Variables Style n Mean±SD Pvalues*
Age (years) Irregular 1 223 47.51±11.89 0.609
Regular 575 46.92±12.05  
Blood loss (ml) Irregular 689 742.57±1 311.68 0.562
Regular 335 820.03±1 640.84  
Operating time (minutes) Irregular 1 219 202.31±104.86 0.159†
Regular 575 242.46±103.79  
Total transfusion (ml) Irregular 1 223 449.93±896.24 0.854
Regular 575 468.05±873.57  
Blood product transfusion (ml) Irregular 1 223 412.68±783.35 0.636
Regular 575 420.52±780.70  
Erythrocyte transfusion (ml) Irregular 1 223 84.98±265.99 0.022
Regular 575 104.35±312.16  
Whole blood transfusion (ml) Irregular 1 223 278.01±659.93 0.011
Regular 575 231.13±539.48  
Plasma transfusion (ml) Irregular 1 223 42.77±176.10 <0.001
Regular 575 77.57±385.73  
Autoblood transfusion (ml) Irregular 1 223 37.25±311.41 0.212
Regular 575 47.53±273.74  
Alpha-fetoprotein (ng/ml) Irregular 635 950.79±3 351.53 <0.001
Regular 281 1 440.00±4 338.47  
Carcinoembryonic antigen (ng/ml) Irregular 573 4.69±13.37 0.012
Regular 269 8.94±75.57  
CA19-9 (ng/mL) Irregular 425 81.96±485.26 <0.001
Regular 233 182.65±684.17  
Total bilirubin (μmol/L) Irregular 1 002 22.29±39.85 <0.001
Regular 507 30.32±65.16  
Direct bilirubin (μmol/L) Irregular 998 9.54±26.39 <0.001
Regular 507 14.62±37.57  
Alkaline phosphatase (U/L) Irregular 864 94.20±83.74 <0.001
Regular 406 140.92±153.36  
Albumin (g/L) Irregular 1 175 40.53±5.04 0.550
Regular 562 39.84±4.71  
Number of segments resected Irregular 1 223 2.33±1.20 <0.001
Regular 575 2.58±0.97  
Largest tumor size (cm) Irregular 1 122 65.22±41.00 <0.001
Regular 343 89.08±50.37  
Number of complication Irregular 1 223 0.21±0.61 0.116
  Regular 575 0.23±0.67  
Total LOS (days) Irregular 1 223 25.83±17.39 0.043
Regular 575 25.19±14.17  
Postoperative LOS (days) Irregular 1 223 15.13±13.25 0.033
Regular 575 14.65±9.42  
Preoperative LOS (days) Irregular 1 223 10.71±8.50 0.603
Regular 575 10.54±7.90  
*Independent samplest-test.†Operating time was not significant when analyzed independently, but it was significant when analyzed dependently.
Table 7.Multivariate analysis of factors associated with morbidity in all cases
Variables Odds ratio Pvalues
Microwave in-line resection (yes/no) 1.668 0.034
Postoperative LOS (d) 1.116 <0.001
Albumin (g/L) 0.958 0.041
Resection style (anatomical/non-anatomical) 0.860 0.450*
*Resection style (regular/irregular) was not significant with multivariate analysis.
Table 8.Multivariate analysis of factors associated with blood loss in all cases
Variables Odds ratio Pvalues
Gender (female/male) 0.530 0.027
Laparoscopic resection (yes/no) 6.279 0.001
Ultrasound in-line resection (yes/no) 0.361 0.019
Resection style (anatomical/non-anatomical) 0.841 0.484*
*Resection style (regular/irregular) was not significant when analyzed dependently.
Table 9.Univariate analysis of variance associated with operating time in all cases
Variables Means
95% confidence interval
Pvalues
Previous abdominal surgery        
No 419.223
356.663-481.784
<0.001
Yes 446.968
384.211-509.724
 
Laparoscopic resection        
No 406.928
345.347-468.509
<0.001
Yes 459.263
394.282-524.243
 
Child-Pugh        
A 403.187
340.926-465.448
<0.001
B or C 463.004
397.745-528.263
 
≥3 segments resected        
No 419.307
356.734-481.880
<0.001
Yes 446.884
384.366-509.401
 
Blood loss        
<1000 ml 404.721
341.868-467.575
<0.001
≥1000 ml 461.470
398.576-524.364
 
Anatomical resection*    
No 419.208
356.782-481.634
<0.001
Yes 446.983
384.291-509.675
 
*Resection style (regular/irregular) was significant when analyzed dependently.
Table 10.Multivariate analysis of variance associated with style of resection
Variables Regular Irregular Pvalues
Operating time (min)* 242.46±103.792 202.31±104.861 <0.001
Blood loss (ml) 820.03±1640.843 742.57±1311.680 0.235
Morbidity 13.91% (80/575) 13.49% (165/1223) 0.240
Mortality 0.17% (1/575) 0.65% (8/1223) 0.781
Post-operative LOS (days) 14.65±9.423 15.13±13.254 0.235
*Operating time was significantly different when analyzed dependently.
  1. grants from the National Natural Science Foundation of China (No. 81341067) and 54th China Postdoctoral Science Foundation (No. 43229).