Liver scintigraphy is useful for selecting candidates for preoperative transarterial chemoembolization among patients with hepatocellular carcinoma and chronic liver disease

Nuclear imaging methods for the prediction of postoperative morbidity and mortality in patients undergoing localized, liver-directed treatments: a systematic review

Background

Several nuclear imaging methods may predict postoperative liver function and outcome, but none has achieved recommendations in clinical guidelines. The purpose of this systematic review was to summarize the existing knowledge on this topic.

Methods

MEDLINE and Web of Science were searched for studies investigating nuclear medicine imaging methods for the prediction of postoperative liver function in patients undergoing localized, liver-directed treatments. The postoperative endpoints were clinical outcome (morbidity and mortality) as well as measures of postoperative liver function, e.g., liver function assessed by biochemical tests or nuclear imaging.

Results

A total of 1352 references were identified, of which 82 fulfilled the eligibility criteria and were included in the review. Most studies (n = 63) were retrospective studies. The vast majority of studies assessed [^99mTc]Tc-galactosyl serum albumin (GSA) (n = 57) and [^99mTc]Tc-mebrofenin (n = 19). Liver resection was entirely or partly major (involved at least three segments) in 78 reports. There were notable variations in the research methodology, e.g., image acquisition, imaging variables, and endpoints. Thirty-seven studies reported on postoperative mortality, of which most reported descriptive data at the patient level. Of the four reports that performed multivariate analyses, two showed significant predictive results of isotope-based preoperative tests. Fifty-two papers presented data on postoperative liver failure. Multivariate predictive analyses were performed in eighteen trials, of which fifteen showed the significant value of nuclear medicine tests.

Conclusion

There is sparse evidence supporting the significant value of nuclear medicine imaging methods in predicting postoperative mortality. In contrast, a notable number of trials showed a significant prediction of liver failure in multivariate analyses. The research methodology was heterogeneous and exploratory in most trials. Documentation of nuclear medicine tests in this setting awaits the results of properly designed, prospective trials with the standardization of both the nuclear medicine test and endpoints.

Usefulness of examining hepatic functional volume using technetium-99m galactosyl serum albumin scintigraphy in hepatocellular carcinoma

OBJECTIVES

The aim of the study was to clarify the clinical significance of single-photon emission computed tomography/computed tomography (SPECT/CT) imaging in terms of technetium-99m galactosyl human serum albumin (99mTc-GSA) scintigraphy. To this end, we examined the relationship using data from surgical records of 67 patients with hepatocellular carcinoma who underwent hepatectomy.

MATERIALS AND METHODS

Liver functional parameters or functional volume was estimated by 99mTc-GSA scintigraphy and computed tomography volumetry was used to estimate morphological volume.

RESULTS

Liver uptake ratio at 15 min (LHL15) was correlated with the indocyanine green retention rate at 15 min (ICGR15; R=-0.608, P<0.01); however, five patients (7.5%) had values outside this correlation. In these patients, LHL15 reflected clinical status and patient outcomes more. Although morphological and functional volumes were well correlated (P<0.01), functional volume was decreased in the diseased liver with portal vein tumor thrombus or portal vein embolization. By applying 99mTc-GSA volumetry, portal pressure and alkaline phosphatase level were correlated with decreased volume of the embolized liver, and platelet count and cholesterol level were correlated with increased volume of the nonembolized liver (P<0.05). By measuring functional volume, four patients who were functionally borderline on the basis of the ICGR15 test safely underwent scheduled major hepatectomy.

CONCLUSION

Under the ICGR15 test as the standard for preoperative hepatic function, auxiliary application of LHL15 and functional volumetry provides useful information on hepatocellular carcinoma patients undergoing hepatectomy.

Preoperative portal vein embolization (PVE) for patients with hepatocellular carcinoma can improve resectability and may improve disease-free survival

BACKGROUND

The aim of this study is to identify the efficacy of portal vein embolization (PVE) before right hepatectomy in patients with hepatocellular carcinoma (HCC) with regard to hepatic function, surgical stress, and survival benefit.

METHODS

Fifty-five patients with HCC underwent right hepatectomy between 1999 and 2009. Preoperative PVE was performed in 19 patients (PVE group) and was not applied in 36 patients (non-PVE group). Changes in liver function and volume were investigated in PVE group. Short and long clinical outcomes after the surgeries were compared between the two groups.

RESULTS

The percentage of future liver remnant (%FLR) before PVE was significantly lower (37.8%) in PVE group than in non-PVE group (58.1%) but increased remarkably after PVE (from 37.8% to 55.0%, P < 0.0001). Cumulative disease-free survival and overall survival rates in PVE group were significantly superior to those in non-PVE group (P = 0.010 and 0.049, respectively). Although surgical stress estimated by E-PASS scores and CRP value was not different between the groups, the postoperative value of PT on postoperative day 3 in PVE group was significantly better than in non-PVE group.

CONCLUSIONS

Preoperative PVE improves resectability and may improve disease-free survival for patients with HCC requiring right hepatectomy.

Usefulness of measuring hepatic functional volume using Technetium-99m galactosyl serum albumin scintigraphy in bile duct carcinoma: report of two cases

We report the usefulness of measuring functional liver volume in two patients undergoing hepatectomy. Case 1 involved a 47-year-old man with hepatitis B virus infection. The indocyanine green test retention rate at 15 min (ICGR15) was 14%. Liver uptake ratio (LHL15) by technetium-99 m galactosyl human serum albumin ((99m)Tc-GSA) liver scintigraphy was 0.91. The patient displayed hilar bile duct carcinoma necessitating right hepatectomy. After preoperative portal vein embolization (PVE), future remnant liver volume became 54% and functional volume by (99m)Tc-GSA became 79%. Although the permitted resected liver volume was lower than the liver volume, scheduled hepatectomy was performed following the results of functional liver volume. Case 2 involved a 75-year-old man with diabetes. ICGR15 was 27.4% and LHL15 was 0.87. The patient displayed bile duct carcinoma located in the upper bile duct with biliary obstruction in the right lateral sector. The right hepatectomy was scheduled. After PVE, future remnant volume became 68% and functional volume became 88%. Although ICGR15 was worse as 31%, planned hepatectomy was performed due to the results of functional volume. In the liver with biliary obstruction or portal embolization, functional liver volume is decreased more than morphological volume. Measurement of functional volume provides useful information for deciding operative indication.

Graft size, donor age, and patient status are the indicators of early graft function after living donor liver transplantation

No reliable model for predicting early graft function and patient survival after living donor liver transplantation (LDLT) exists. The aim of this study was to establish a new formula for predicting early graft function and prognosis using technetium-99m galactosyl-human serum albumin (Tc-GSA) liver scintigraphy. The ratio of the hepatic uptake ratio of Tc-GSA to the clearance index of Tc-GSA (LHL/HH) was determined 7 days after LDLT. There were 22 patients with a ratio greater than 1.3 and 6 patients with a ratio less than 1.3. Graft function on the 14th postoperative day (POD) was compared between the 2 groups. A new formula to predict the LHL/HH score was established as follows: LHL/HH (predictive score) = 0.011 x graft weight (%) - 0.016 x donor age - 0.008 x Model for End-Stage Liver Disease score - 0.15 x shunt (if present) + 1.757 (r(2) = 0.497, P < 0.01). This predicted LHL/HH ratio was compared to the graft function on POD 14 for 110 LDLT patients. The total bilirubin (TB) and prothrombin time international normalized ratio (PT-INR) in the group with an LHL/HH score > or = 1.3 were lower than those in the group with an LHL/HH score < 1.3. The TB, PT-INR, and volume of ascites in the group with a predictive score > or = 1.3 (n = 86) were lower than those in the group with a score < 1.3 (n = 24). The 6-month survival probability was improved in the group with a predictive score > or = 1.3. In conclusion, this preoperative calculated LHL/HH score is correlated with graft function and short-term prognosis. Thus, this predictive model may allow transplant surgeons to use a living donor left lobe graft with greater confidence.

[Evaluation of liver function before living donor liver transplantation and liver resection]

Liver resection is the curative therapeutic option for hepatocellular carcinoma, biliary tumors, metastases of colorectal and other extrahepatic tumors, living donor liver transplantation and other benign liver diseases.

AIM OF STUDY

To summarize the evaluation methods of liver function before living donor liver transplantation and liver resection.

METHOD

We summarize the literature about the evaluation of liver function.

RESULTS

Perioperative mortality is determined mostly by the extent of preoperative evaluation focused on the liver. After resection the remnant liver parenchyma must cope with the challenge caused by increased metabolism, portal overflow, decreased vascular bed and biliary tract and oxidative stress following the operation. If the remnant liver is unable to grow up to this challenge, acute liver failure occurs. This maintains the necessity of determining the hepatic functional reserve and the hepatic remnant volume. Child-Pugh classification is widely spread to predict outcome. Dynamic functional tests such as indocyanine green retention test, galactosyl human serum albumin scintigraphy and aminopyrine breath tests can be used to evaluate hepatic reserve. To determine remnant liver volume modern imaging processes such as CT volumetry and hepatobiliary scintigraphy are available.

CONCLUSION

After the detailed evaluation resection can be limited to an extent which is oncologically radical enough (1% remnant liver tissue/kg) and spares parenchyma which can ensure survival yet. With careful preoperative examination mortality can be reduced even to reach zero.

Relationship between 99mTc-GSA scintigraphic indices of liver function reserve and portal circulation in patients with chronic liver disease

OBJECTIVES

In order to predict the prognosis or complications of portal hypertension in patients with chronic liver disease, it is important to evaluate both hepatic functional reserve and portal circulation. On (99m)Tc-galactosyl human serum albumin ((99m)Tc-GSA) scintigraphy, the index of blood clearance (HH15) and receptor index (LHL15) have been widely used to evaluate the hepatic functional reserve. However, the relationship between these indices and portal circulation is unknown. The purpose of this study was to examine the relationship between HH15 and LHL15 and portosystemic shunts evaluated with arteriographic portography or esophagogastroduodenoscopy.

METHODS

A total of 82 patients with chronic liver disease (mean age, 66.7 years) who underwent (99m)Tc-GSA scintigraphy, arteriographic portography, and esophagogastroduodenoscopy were enrolled. HH15 and LHL15 were obtained from dynamic (99m)Tc-GSA scintigraphy. The patients were divided into three groups according to the arteriographic portography findings: group 1, no portal collateral circulation; group 2, mild collateral development; and group 3, moderate to severe collateral development. They were also divided into three groups based on the esophagogastroduodenoscopic findings: group A, no varices; group B, small-caliber varices; and group C, enlarged varices. The Kruskal-Wallis test was used to compare each index among these groups. Receiver operating characteristic (ROC) analysis was used to determine whether each index was an indicator for the presence of portosystemic shunts.

RESULTS

Both HH15 and LHL15 differed significantly between groups 1 and 2 and between groups 1 and 3. However, only HH15 differed significantly between groups A and B and between groups A and C. On the basis of the ROC analysis, the HH15 threshold value of 0.62 yielded both excellent sensitivity (83.9%) and specificity (84.6%) for the presence of portosystemic shunts, as evaluated with arteriographic portography. The HH15 threshold value of 0.64 yielded both good sensitivity (66.1%) and specificity (69.2%) for the presence of portosystemic shunts, as evaluated with esophagogastroduodenoscopy, whereas no adequate threshold value of LHL15 was found for the presence of portosystemic shunts.

CONCLUSIONS

HH15 is a potent indicator of the presence of portosystemic shunts in chronic liver disease.

Preoperative assessment of liver function

At the present time, the decision to resect and the choice of the extent ofa hepatic resection are largely based on surgical judgment. The CP score is the best assessment tool we can now employ. There is uniform agreement that even segmental resections are not possible in the vast majority of Child Class B patients, CP score 7 to 9. The CP score can be augmented by radiographic testing, ICG retention testing, and by assessing tumor extent and the severity of the patient's cirrhosis at surgery. Surgeons need a simple means to assist with liver function evaluation--a test to augment the CP score. Although determining ICG retention is simple, it is questionable whether it adds to one's ability to define the poor-risk patient with better accuracy than the CP score. Abundant data exist to dispute the accuracy and reproducibility of ICG retention. That surgeons use it says more about the fervent desire to find a test that supports clinical judgment in these difficult patients than the scientific validity of the test. Whether a series of tests would better define the Child-Pugh Class A patient who is also a relatively poor risk is not clear at present. Many investigations demonstrate the correlation of various assessment tools with each other, yet nothing distinguishes them in predicting risk beyond what is learned from the CP score. In a group of CP Class A patients, the extent of the disease, the nature of underlying cirrhosis, and the extent of resection provide the clinical backdrop against which a decision for resection must be made. It may well be that one test may not do it, or that one single assessment of the ICG or the 15-minute receptor volume of GSA may be inadequate to project the nuances of liver function. Thus, 99m-Tc GSA scintigraphy will provide volumetric receptor data, as well as kinetic distribution curves, and may prove a useful test in the future. Whether GSA is ultimately to be proven useful requires a correlation of the test with actual clinical outcomes, rather than correlation with other tests or with the CP score. Discovering which patients are the poor risk Child Class A patients is the desired goal. To have value, the GSA scan must augment, not mimic, the CP score. In view of the fact that experienced surgeons appear to be astute in their ability to select patients for hepatic resection, finding a more refined test will require large numbers of patients at several centers to correlate the test results and the outcomes against the spectrum of postoperative liver failure, including death. It appears that one lesson learned from portal vein embolization is that functional liver volume can be preserved. The compensatory hyperplasia that occurs in the contralateral hepatic lobe demonstrates two important features: (1) function of the opposite lobe has been transferred when evaluated by 99m-Tc-GSA, and (2) one considerable metabolic drain on the postoperative recovery from hepatic resection (ie, liver regeneration) can be attended to before the surgery. Cirrhotic livers do regenerate, but more slowly. Thus, pregrowing the remnant section of liver eliminates one stress on liver reserves following liver resection. For hepatocellular carcinoma or metastasis in cirrhotic patients, portal vein occlusion may be the best way to improve hepatic functional reserve. ICG retention may not corroborate return-to-baseline hepatic function within 2 weeks of portal vein occlusion,but may demonstrate a return to baseline when studied 6 to 8 weeks following the procedure. 99m-Tc-GSA is presently the best means to document compensatory hyperplasia and, possibly, a shift of functional reserve to the planned remnant of a more than four-segment hepatic resection. Whether this will predict the safe outcome of resection remains to be seen.

Combined interventional therapies of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignancies in the world, responsible for an estimated one million deaths annually. It has a poor prognosis due to its rapid infiltrating growth and complicating liver cirrhosis. Surgical resection, liver transplantation and cryosurgery are considered the best curative options, achieving a high rate of complete response, especially in patients with small HCC and good residual liver function. In nonsurgery, regional interventional therapies have led to a major breakthrough in the management of unresectable HCC, which include transarterial chemoembolization (TACE), percutaneous ethanol injection (PEI), radiofrequency ablation (RFA), microwave coagulation therapy (MCT), laser-induced thermotherapy (LITT), etc. As a result of the technical development of locoregional approaches for HCC during the recent decades, the range of combined interventional therapies has been continuously extended. Most combined multimodal interventional therapies reveal their enormous advantages as compared with any single therapeutic regimen alone, and play more important roles in treating unresectable HCC.

Decreasing mortality of bile leaks after elective hepatic surgery

BACKGROUND

Bile leak is a serious complication following major hepatic surgery. It is associated with significant mortality rates if reoperative management is attempted. We evaluated our experience with aggressive, nonoperative management of postoperative biliary complications.

METHODS

All medical records of patients undergoing major liver resection, cryosurgery or radiofrequency ablation from September 1996 through March 1999 were reviewed.

RESULTS

Seventy-four patients were identified, and 9 (12%) developed bile leaks. Biliary leaks were investigated with endoscopic retrograde cholangiopancreatography (ERCP) and treated with endoscopic stenting when possible. The bile leak was found to originate from the resected duct stump or ablated surface of the liver in all cases. Patients were treated with ERCP stent placement (5), computed tomography-guided percutaneous drainage (3), and hepaticojejunostomy "chimney" (1). Six of 9 patients had resolution of their bile leak with the mean time of removal of the drain of 4.7 months. There was only 1 death, and that patient died nearly 3 months after surgery from complications not directly related to the bile leak.

CONCLUSIONS

Bile leak after liver resection can be managed nonoperatively in most cases with a combination of percutaneous drain placement and biliary stenting. Most bile leaks will close with time, although a drain may be required for many months.

Hepatectomy simulation discrepancy between radionuclide receptor imaging and CT volumetry: influence of decreased unilateral portal venous flow

BACKGROUND

Regional dysfunction demonstrated by Tc-99m-diethylenetriamine-penta-acetic acid-galactosyl human serum albumin (GSA) scintigraphy due to regional decrease in the portal venous flow has previously been reported. In this study, we call attention to the significance of unilateral portal venous flow decrease for preoperative hepatectomy simulation, and evaluate the hepatectomy simulation discrepancy between Tc-99m-GSA single-photon emission computed tomography (SPECT) and CT volumetry.

METHODS

Twenty-four hepatectomy candidates underwent preoperative hepatectomy simulation by both Tc-99m-GSA SPECT and CT volumetry. Both anatomical and functional resection ratios were calculated by means of CT volumetry and Tc-99m-GSA SPECT, respectively. The differences and ratios between anatomical and functional resection ratios were calculated in all patients, and compared in patients with and without unilateral portal venous flow decrease.

RESULTS

Anatomical resection ratios were 28.0 +/- 11.7 (mean +/- standard deviation) in patients with unilateral portal venous flow decrease, and 42.1 +/- 15.7 in patients without unilateral portal venous flow decrease (p = 0.0127). Functional resection ratios were 14.7 +/- 12.8 in patients with unilateral portal venous flow decrease and 40.5 +/- 14.6 in patients without (p = 0.0004). The differences between anatomical and functional resection ratios were 13.0 +/- 7.9 in patients with unilateral portal venous flow decrease and 5.6 +/- 3.1 in patients without (p = 0.0099). The ratios between anatomical and functional resection ratios were 0.48 +/- 0.29 in patients with unilateral portal venous flow decrease and 0.86 +/- 0.10 in patients without (p = 0.0018). In 12 of the 13 patients with unilateral portal venous flow decrease, anatomical resection ratios were found to be larger than functional resection ratios, whereas this happened in only 6 of 11 patients without unilateral portal venous flow decrease (p = 0.0063).

CONCLUSION

Unilateral portal venous flow decrease is suspected to be a major factor in the discrepancy between hepatectomy simulations with radionuclide receptor imaging and CT volumetry.

Locoregional therapies for hepatocellular carcinoma: a critical review from the surgeon's perspective

OBJECTIVE

This article reviews the current results of various locoregional therapies for hepatocellular carcinoma (HCC), with special reference to the implications for surgeons.

SUMMARY BACKGROUND DATA

Resection or transplantation is the treatment of choice for HCC, but most patients are not suitable candidates. The past decade has witnessed the development of a variety of locoregional therapies for HCC. Surgeons are faced with the challenge of adopting these therapies in the management of patients with resectable or unresectable HCC.

METHODS

A review of relevant English-language articles was undertaken based on a Medline search from January 1990 to August 2001.

RESULTS

Retrospective studies suggested that transarterial chemoembolization is an effective treatment for inoperable HCC, but its perceived benefit for survival has not been substantiated in randomized trials, presumably because its antitumor effect is offset by its adverse effect on liver function. Nonetheless, it remains a widely used palliative treatment for HCC not amenable to resection or ablative therapies, and it also plays an important role as a treatment of postresection recurrence and as a pretransplant therapy for transplantable HCC. Better patient selection, selective segmental chemoembolization, and treatment repetition tailored to tumor response and patient tolerance may improve its benefit-risk ratio. Transarterial radiotherapy is a less available alternative that produces results similar to those of chemoembolization. Percutaneous ethanol injection has gained wide acceptance as a safe and effective treatment for HCCs 3 cm or smaller. Uncertainty in tumor necrosis limits its potential as a curative treatment, but its repeatability allows treatment of recurrence after ablation or resection of HCC that is crucial to prolongation of survival. Cryotherapy affords a better chance of cure because of predictable necrosis even for HCCs larger than 3 cm, but its use is limited by a high complication rate. There has been recent enthusiasm for heat ablation by microwave, radiofrequency, or laser, which provides predictable necrosis with a low complication rate. Preliminary data indicated that radiofrequency ablation is superior to ethanol injection in the radicality of tumor ablation. The advent of more versatile radiofrequency probes has allowed ablation of HCCs larger than 5 cm. Recent studies have suggested that combined transarterial embolization and heat ablation is a promising strategy for large HCCs. Thus far, no randomized trials comparing various thermoablative therapies have been reported. It is also uncertain whether a percutaneous route, laparoscopy, or open surgery affords the best approach for these therapies. Thermoablative therapies have been combined with resection or used to treat postresection recurrence, and they have also been used as a pretransplant therapy. However, the value of such strategies requires further evaluation.

CONCLUSIONS

Advances in locoregional therapies have led to a major breakthrough in the management of unresectable HCC, but the exact role of the various modalities needs to be defined by randomized studies. Novel thermoablative techniques provide the surgeon with an exciting opportunity to participate actively in the management of unresectable HCC. Locoregional therapies are also useful adjuncts in the management of patients with resectable or transplantable disease. Hence, surgeons must be equipped with the latest knowledge and techniques of ablative therapy to provide the most appropriate treatment for the wide spectrum of patients with HCC.

Correlation of serum basic fibroblast growth factor levels with clinicopathologic features and postoperative recurrence in hepatocellular carcinoma

BACKGROUND

Basic fibroblast growth factor (bFGF) is an important positive regulator of tumor angiogenesis. This study evaluated the role of serum bFGF as a biological marker of tumor invasiveness and postresection recurrence in hepatocellular carcinoma (HCC).

METHODS

Concentrations of bFGF in preoperative serum samples in 88 patients undergoing resection of HCC were measured by a quantitative enzyme-linked immunosorbent assay. A single pathologist performed histopathologic examination of all tumor specimens. All patients were prospectively monitored for tumor recurrence.

RESULTS

The preoperative serum bFGF levels ranged from <0.22 to 71.2 pg/mL (median 10.8 pg/mL). There was significant correlation between high serum bFGF levels and large tumor >5 cm, presence of venous invasion or advanced pTNM stage. Patients with a serum bFGF level >10.8 pg/mL had worse disease-free survival than those with a level <10.8 pg/mL (median disease-free survival 11.2 versus 20 months, P = 0.044). Serum bFGF level >10.8 pg/mL (P = 0.035) and tumor size >5 cm (P = 0.004) were independent preoperative factors that predicted early recurrence after resection of HCC.

CONCLUSIONS

This study supports a role of bFGF in tumor growth and invasion in HCC. A high preoperative serum bFGF level appears to be predictive of invasive tumor and early postoperative recurrence. The clinical implications of serum bFGF level in HCC warrant further investigation.

The role of macroscopic classification in nodular-type hepatocellular carcinoma

BACKGROUND

Little has been reported on the role of macroscopic classification of hepatocellular carcinoma (HCC). We hypothesized that macroscopic classification of HCC might have a strong correlation with long-term prognosis after hepatectomy.

METHODS

Four hundred and four patients with a macroscopically nodular type of HCC who underwent a hepatectomy were studied. The patients were divided into three groups: single nodular (SN) group (n = 312); single nodular with extranodular growth (SNEG) group (n = 52); and confluent multinodular (CMN) group (n = 40). Clinicopathological variables were compared among the three groups. The patient survival rate was also compared among the three groups. Finally, a multivariate analysis was performed to clarify the independent significant variables of the long-term prognosis. To confirm the consistency of the results in small-size HCC, the same analyses were made using patients whose tumor size was equal to or less than 3 cm in diameter.

RESULTS

The alpha-fetoprotein value, tumor size, and rate of absolute noncurative operation in the SNEG group were higher than in other groups. The positive rate of both portal vein invasion of cancer cells and intrahepatic metastasis in the SN group was lower than those in other groups. The rate of poorly differentiated histology in the SN group was lower than in the other groups. Patient survival in the SNEG group was worst among the three groups. However, patient survival showed no significant difference between the SN and CMN groups. The multivariate analysis showed that the presence of intrahepatic metastasis, the macroscopic classification of SNEG type, and absolute noncurative operation were independent poor prognostic indicators. The results for patients with small HCCs measuring equal to or less than 3 cm in diameter were quite similar to the results for the other patients.

CONCLUSIONS

Among the three subtypes of macroscopically nodular type of HCCs, the SNEG type showed higher rates of portal vein invasion of cancer cells, intrahepatic metastasis, and poorly differentiated histology. The patient survival rate in the SNEG type was worst, and the SNEG type was an independent poor prognostic indicator. The macroscopic classification of HCC, especially the SNEG type, helps predict the long-term outcome after hepatectomy.