Objectives: Liver transplant performed for hepa­tocellular carcinoma must adhere to criteria for the size and number of focal hepatic lesions to lower the incidence of recurrence and achieve survival rates comparable to patients transplanted for other indications. Since the Milan criteria were established in 1996, there have been many less restrictive criteria yielding similar results. Our aim was to identify the prognostic factors for patient survival and for recurrence of hepatocellular carcinoma for patients within and beyond the Milan criteria.

Materials and Methods: This retrospective and prospective analysis was conducted in 60 adult patients who underwent right lobe living-donor liver transplant for cirrhosis complicated by hepatocellular carcinoma at Dar Al Fouad Hospital, 6th of October City, Egypt, between August 2001 and June 2012. The median follow-up was 39.5 months.

Results: Overall 1-, 3-, and 5-year survival rates were 98.3%, 93.5%, and 71.4%. Overall disease-free survival rates at 1, 3, and 5 years were 96.6%, 93.5%, and 64.2%. There was no statistically significant difference in overall survival time between patients within and beyond the Milan criteria. Factors affecting recurrence were the tumor grade, lobar distribution, size of the largest nodule, and the total tumor burden in the explanted liver. Recurrence adversely affected survival.

Conclusions: Using our criteria of a single tumor ≤ 6 cm, or 2 to 3 tumors with the largest ≤ 4.5 cm, or 4 to 5 tumors with the largest ≤ 3 cm and total tumor size ≤ 8 cm resulted in overall survival comparable to patients within the Milan criteria.

Key words : Expanded Milan criteria, Hepatocellular carcinoma downstaging, Hepatocellular carcinoma recurrence, Milan criteria

Introduction

Worldwide, hepatocellular carcinoma (HCC) accounts for 80% of primary liver neoplasms, representing the fifth most common cancer and the third most common cause of cancer-related death. The condition results in over 1 million deaths annually.¹ Its worldwide incidence is increasing, ranging from 3% to 9% annually.² This increase in HCC is related to the prevalence of hepatitis B virus and hepatitis C virus infections and to the growing incidence of fatty liver diseases caused by metabolic derangements and alcohol abuse.³ Egypt is plagued by the highest prevalence of hepatitis C virus infection in the world, with estimates of prevalence ranging from 6% to 28% and a reported average prevalence of 13.8%.⁴ In Egypt, HCC reportedly occurs in about 4.7% of patients with chronic liver disease.⁵

Liver transplant is the best curative treatment option for patients with HCC and liver cirrhosis when resection is contraindicated and palliative ablation, such as radiofrequency ablation (RFA) and transarterial chemoembolization (TACE), is also contraindicated.⁶ The idea of transplant for HCC was initially proposed because, in theory, it completely removes the tumor and underlying diseased liver while alleviating portal hypertension. Both deceased and living donors are used.⁷ Tumor recurrence is the cause of death in 3% to 26% of cirrhotic patients with HCC who undergo transplant.⁸

The Milan criteria for liver transplant were established in 1996 and are associated with low recurrence rates and survival rates similar to those seen in patients transplanted for cirrhosis without HCC. The Milan criteria specify that a single tumor measures less than 5 cm and that 2 to 3 tumors may be present if none are larger than 3 cm. There must be no extrahepatic spread and no vascular invasion.⁹ Since 1996, several publications have suggested that a favorable outcome is possible for patients beyond the Milan criteria. Among the expanded criteria are those of the University of California, San Francisco (UCSF) from 2001,^10,11 the Barcelona Clinic Liver Cancer Group from 2002,12 the up-to-7 criteria from 2007,¹³ the Hangzhou criteria from 2008,¹⁴ the 5/5 criteria from 2009,¹⁵ and the Shanghai criteria from 2009.¹⁶

In our daily practice, we encounter patients with HCC requiring liver transplant who have advanced tumors of various stages; we need to balance the living-donor hazards with the expected recipient outcome. Our aim is to analyze our transplanted HCC patients in an attempt to identify prognostic factors for tumor recurrence and patient survival.

Materials and Methods

This retrospective and prospective study was conducted in adult patients who underwent right lobe living-donor liver transplant (LDLT) for cirrhosis complicated by HCC at Dar Al Fouad Hospital, 6th of October City, Egypt between August 2001 and June 2012. The study was approved by the Ethical Review Committee of the Institute. All of the protocols conformed with the ethical guidelines of the 1975 Helsinki Declaration. Written informed consent was obtained from all participants.

Preoperative evaluation
All patients underwent a thorough history and physical examination. Laboratory analysis included the bilirubin and creatinine levels and the international normalized ratio, which were used to calculate the Child-Pugh score and the Model for End-Stage Liver Disease (MELD) score. Imaging studies included duplex ultrasonography and triphasic computerized tomography (CT) in arterial, portal venous, and hepatic venous phases to assess the focal hepatic lesions (FHLs). Bone scans and positron emission tomography were used to detect distant spread, if needed. The tumor number and size were detected, and the total tumor size (tumor load) was calculated by adding the diameters of all FHLs.

Criteria for transplant in patients with hepato­cellular carcinoma
The criteria for transplant included the size and number of lesions: either a single tumor ≤ 6 cm; 2 or 3 tumors with the largest ≤ 4.5 cm and the total tumor size ≤ 8 cm; or 4 or 5 tumors with the largest ≤ 3 cm and the total tumor size ≤ 8 cm. Patients were required to have no extrahepatic spread (distant or local), no suspicion for macrovascular invasion, and no malignant portal vein thrombosis. The alpha-fetoprotein (AFP) level was required to be below 1000 ng/mL, and patients needed to fulfill all other general criteria for liver transplant such as good renal function and the absence of sepsis.

Preoperative ablative therapy
Either RFA, TACE, ethanol injection, or a com­bination of these were used according to each individual’s situation. Patients were required to have adequate liver reserve to tolerate therapy (bilirubin level ≤ 3 mg, no or minimal ascites, and a MELD score < 15). Bridging therapy was indicated when the expected time to transplant exceeded 1 month from the first clinic visit. Downstaging therapy was indicated when there was a single lesion measuring 6 to 8 cm; 2 or 3 lesions, none > 5.5 cm, with a total diameter ≤ 9 cm; or 4 or 5 lesions, all < 4 cm, with a total diameter ≤ 9 cm.

Criteria for successful downstaging
Downstaging was considered successful when the tumor size or number regressed to within our institutional criteria for transplant. A follow-up of 3 months after downstaging was required before LDLT. Positron emission tomography-CT and AFP levels were used to evaluate tumor behavior and aggressiveness.

Operative evaluation
To avoid transplant in patients with advanced HCC, some patients with preoperative equivocal CT results underwent diagnostic laparoscopy. Our protocol was to surgically explore the recipient before making the donor incision. We searched carefully for metastases, and any suspicious lymph nodes were sent for frozen section. Our protocol called for aborting the trans­plant if any metastases were found; however, we did not encounter this situation in our series. The portal vein was checked for thrombosis, and the hepatic veins were clamped early to avoid spread.

Histopathology of the explanted liver
All explants were examined for the number, size, and site of nodules; the presence of vascular invasion (macrovascular or microvascular); and the grade of the tumor. The Modified Edmondson-Steiner clas­sification was used, where grade 1 was well dif­ferentiated, grade 2 was moderately differentiated, and grade 3 was poorly differentiated.

Follow-up
Our standard immunosuppression protocol involved the administration of tacrolimus and low-dose steroids. Patients were followed after transplant with daily clinical, laboratory (eg, AFP), and radiologic (eg, abdominal ultrasonography) evaluation for the first month, then weekly evaluation for the next 3 months, then monthly evaluation for the remainder of the first year; follow-up was conducted every 6 months thereafter. For any suspicion of recurrence, we performed a triphasic CT (ie, FHL with enhancement in the early arterial phase and rapid washout in the venous phase) and a metastatic workup (ie, chest CT and bone scan). For any confirmed recurrence, the timing, management, and outcome were noted.

Statistical analyses
Statistical analyses were performed using software (IBM SPSS version 21.0, IBM Corp., Armonk, NY, USA). Data were expressed as the mean ± standard deviation for quantitative parametric measures,
the median with percentiles for quantitative nonparametric measures, and the number and percentage for categorized data. Comparisons between 2 independent groups for nonparametric data were performed using the Wilcoxon rank-sum test. Comparisons between more than 2 patient groups for nonparametric data were performed using the Kruskall-Wallis test. Either the chi-square test or Fisher exact test were used to study the association between 2 variables or to compare 2 independent groups for categorized data. Contin­uous data were presented as the median (range) and were analyzed using the Mann-Whitney U test. Survival curves were calculated using the Kaplan-Meier method, and the log-rank test was used to compare group survival. A probability of error of .05 was considered significant, and P values of .01 and .001 were considered significant.

Results

The total number of patients who underwent liver transplant during the study period was 325, and the number of these with HCC was 83. We excluded 23 patients who died from causes other than HCC recurrence (eg, sepsis) within 6 months of transplant. The final analysis included 60 patients who underwent right lobe LDLT for cirrhosis complicated by HCC.

The patient age ranged from 30 to 66 years (median, 54 years). A total of 57 patients were men (95%) and 3 were women (5%). End-stage liver disease was attributed to viral infection in 58 patients (96.66%), including 57 patients with hepatitis C virus (95%) and 1 with hepatitis B virus (1.66%). Two patients (3.33%) had cryptogenic cirrhosis. Pre­operative ablative therapy (TACE, RFA, ethanol injection, or combination) was employed in 20 patients (33.3%) who were expected to have a delay in transplant over 1 month from the initial clinic visit. Four patients (6.7%) were Child–Pugh class A, 20 (33.3%) were class B, and 36 (60%) were class C; the MELD score ranged from 12 to 21 (median, 17). All AFP levels were below 1000 ng /mL (range, 1.96-989 ng/mL; median, 11.4 ng/mL [5.2-75.2]). Preoperative radiologic assessment revealed that 29 patients (48.3%) had a single FHL, 19 (31.7%) had 2 FHLs, and 8 (13.3%) had 3 FHLs; only 4 patients (6.7%) had more than 3 FHLs. The mean total tumor burden was 4.25 ± 1.82 cm (range, 1-8 cm). A total of 19 patients (31.7%) had bilateral FHLs, whereas 32 patients (53.3%) had FHLs confined to the right lobe, and 9 (15%) had lesions confined to the left lobe. In our patient cohort, 46 patients were within the Milan criteria, and 14 were beyond the Milan criteria (Table 1). There were 14 patients (23.3%) with microvascular invasion (MVI); 13 of these were within the Milan criteria and 1 was beyond. The incidence of MVI did not rise when going beyond the Milan criteria.

Postoperative immunosuppression consisted of tacrolimus and steroids in 12 patients (20%) and tacrolimus, steroids, and mofetil mycophenolate in 28 patients (46.7%). The remaining 20 patients (46.7%) discontinued tacrolimus due to the adverse effects and started cyclosporine.

Seven patients (11.66%) experienced HCC recurrence. Four of these were within the Milan criteria and 3 were beyond. Recurrence developed within the first year after liver transplant in 2 patients, between 1 and 3 years in 2 patients, and beyond 3 years in 3 patients. The median time to recurrence was 20 months (range, 3-78 months) after transplant. A total of 4 patients developed a recurrence in the liver graft, 2 patients presented with bone recurrence, and 1 patient presented with recurrence in the lung. We found that tumor recurrence adversely affected survival (Table 2). Of the 7 patients with recurrence, 6 died after developing this complication; there were no deaths among the 54 patients who did not develop recurrence (P = 0).

The median follow-up was 39.5 months (range, 6-120 months). Of the 60 patients enrolled, 54 (90%) are currently alive. Overall 1-, 3-, and 5-year survival rates were 98.3%, 93.5%, and 71.4%. Overall disease-free survival rates at 1, 3, and 5 years were 96.6%, 93.5%, and 64.2%. The overall 1-year, 3-year, and 5-year survival rates in patients within the Milan criteria were 97.8%, 96.6%, and 82%, while in those beyond the Milan criteria the 1-year and 3-year survival rates were 100% and 77.7%. We were not able to calculate the 5-year survival for the group beyond the Milan criteria because only 3 patients in this group survived more than 5 years after transplant. Kaplan-Meier curves were used to compare patients within and beyond the Milan criteria for overall survival and time to recurrence (Figure 1). There was no statistically significant difference in overall survival between the groups. For recurrence, the relation between the groups was significant (P = .06).

Univariate analysis of recurrence and survival were affected by the tumor grade, which inde­pendently affected tumor recurrence and survival (P = .005). Lobar distribution only affected recurrence (P = .09). The size of the largest nodule (P = .05) and total tumor burden in the explanted liver (P = .07) independently affected tumor recurrence.

Stepwise multivariate logistic regression analysis showed that both decreasing patient age (< 52 years) and AFP levels (< 88 ng/dL) were the most sensitive discriminators for predicting increased survival time (F-ratio = 5.81; P < .01). The addition of being within the Milan criteria preoperatively added sensitivity to the age and AFP level (F-ratio = 5.54; P < .01).

Discussion

Unlike other therapies for HCC, liver transplant not only treats the cancer but also replaces the diseased organ. Before the Milan criteria were defined in 1996, liver transplant for HCC was performed according to center-based selection criteria.¹⁷

The Milan group showed actuarial survival of 85% and recurrence-free survival of 92% for patients fitting their criteria, similar to the outcome of patients undergoing liver transplant for non-HCC indica­tions.⁹ Since the Milan criteria were established, many groups have deemed these criteria too restrictive and have attempted to show the safety of expanding them. The UCSF group reported a 5-year survival of 75% using less restrictive criteria derived by retrospectively analyzing 2000 patients. Their criteria are a maximum tumor size of 6.5 cm, or < 3 lesions that are smaller than 4.5 cm in diameter, with a total tumor diameter < 8 cm.¹¹ The original Milan group recently published retrospective data on the outcome in 1112 patients exceeding the Milan criteria. In this study, a 71.2% 5-year overall survival was achieved using the “up-to-7” criteria, where 7 is the sum of the measurement of the largest tumor (cm) and the number of tumors.¹⁸

Living donors offer a graft to patients with HCC without the need for a wait list period and without the requirement of downstaging to qualify for a deceased-donor wait list. According to a multicenter study from Korea involving 237 LDLT and 75 deceased-donor recipients, the 3-year survival was 88% for deceased-donor and 91% for LDLT when the UCSF criteria were met.¹⁹ In a LDLT series of 316 patients from 49 centers in Japan, the 3-year survival was 79% for patients meeting the Milan criteria and 61% for those not meeting criteria.¹⁹

Our primary objective was to evaluate our results in patients with HCC beyond the classic Milan criteria. We found overall 1-, 3-, and 5-year survival rates of 98.3%, 93.5%, and 71.4%. Overall disease-free survival rates at 1, 3, and 5 years were 96.6%, 93.5%, and 64.2%. The 1-year, 3-year, and 5-year survival rates in patients within the Milan criteria were 97.8%, 96.6%, and 82%, whereas in those beyond the Milan criteria, the 1-year and 3-year survival rates were 100% and 77.7%.

Approximately 20% of patients transplanted for HCC have recurrence, a poor predictor of long-term survival.²⁰ There are a number of risk factors for HCC recurrence, including tumor number, tumor size, microvascular invation and tumor dif­ferentiation, bilobar distribution, AFP level, preoperative ablative therapy, and immunosuppression.

Tumor number
In a study by Ito et al, patients with 4 to 10 tumors exhibited 5-year recurrence rates similar to those of patients with ≤ 3 tumors (12.8% vs 17.6%). However, the recurrence rate for patients with ≥ 11 tumors (56.8%) was significantly higher than that seen in patients with fewer tumors (P = .001).²¹ An analysis of 4575 patients in 15 studies, performed by Germani et al in 2010, evaluated the impact of tumor-nodule number on overall survival, disease-free survival, and recurrence after liver transplant. They concluded that patients with ≥ 3 tumors have an increased risk of death compared with those with < 3 tumors.²² In our study, the median number of nodules in the nonrecurrence group was 2 (range, 1-5) and in the recurrence group was 1 (range, 1-2).

Tumor size
Tumor size has been shown to be the most important preoperative predictor for patient survival after liver transplant. Patients with tumors ≥ 5 cm in diameter show a significantly higher recurrence rate than those with smaller tumors.²¹ The hazard ratios associated with increasing tumor size rise in a linear fashion.¹⁸

An analysis of 32 studies by Germani et al in 2010 concluded that overall survival is nearly 5 times lower in patients with a total tumor size ≥ 10 cm, disease-free survival is nearly 2 times lower with a total tumor size ≥ 9 cm, the probability of recurrence after liver transplant is nearly 6 times higher in patients with a largest tumor diameter of ≥ 3 cm, and a tumor size ≥ 5 cm has a probability of disease-free survival after liver transplant nearly 4 times lower and a probability of recurrence nearly 4 times higher.²² The mean size of FHLs in our study was 3.6 cm in the nonrecurrence group and 5.5 cm in the recurrence group; this is consistent with the previous data. The size of the largest nodule (P = .05 [significant]) independently affected tumor recurrence.

Microvascular invasion
Although MVI is a postoperative finding, it carries strong implications for patient outcome. In a 2007 study involving 483 patients, recurrence was 6.5% without MVI and 33.7% with MVI.²³ This was confirmed by Mazzaferro et al in 2009, who observed that MVI results in a higher recurrence rate and subsequently lower overall survival.¹⁸ The presence of MVI is frequently correlated with patients beyond the Milan criteria who have less differentiated tumors.²⁴ As the size of the tumor increases, the incidence of MVI increases.¹⁸ Tumor markers are important predictors of MVI, and des-gamma-carboxyprothrombin in particular can be used to detect latent MVI.²⁵

In our study, 11 patients in the nonrecurrence group demonstrated MVI on histopathologic exam­ination of the explanted liver, while 3 of 7 patients in the recurrence group had MVI. Three patients (50%) who died had MVI. We found that the relation between MVI and the possibility of recurrence is insignificant (P = .16).

Tumor differentiation
The histologic grade of HCC is an important prognostic factor affecting patient survival after liver transplant. In a previous study of 630 patients, recurrence with well-differentiated HCC was 9.4%; it was 20.3% for less differentiated HCC confirmed in the liver explants.²³ In a study of 1056 patients by Mazzaferro et al in 2009, the authors noted that progressively increasing levels of high-grade tumor patterns (grade 3) tended to parallel an increase in the size and number of tumors and the incidence of MVI.18 In another study of 497 patients by D'Amico et al in 2009, histologic grade correlated with HCC recurrence.²⁶ In our study, univariate analysis showed poor differentiation as an independent factor affecting tumor recurrence and survival (P = .005 [highly significant]). It is not feasible to detect the histologic grade preoperatively except by biopsy. When aggressive biologic behavior is suspected, we recommend either close monitoring of tumor behavior or biopsy.

Bilobar distribution
Up to 50% of bilobar HCCs have macroscopic vascular invasion.²⁷ In our study, 41 patients had unilobar FHLs (68.3%); of these, 6 (14.6%) had MVI. A total of 19 patients (31.7%) had bilobar FHLs; of these, 8 (42%) had MVI. The relation between the site of the FHLs (either unilateral or bilateral) and the possibility of recurrence was marginally significant (P = .09).

Tumor markers: alpha-fetoprotein
In a study by Ho and associates in 2004, patients with pretransplant AFP levels greater than 200 ng/mL had greater HCC recurrence.²⁸ In a study of 219 patients by Bertuzzo and associates in 2011, a factor affecting overall survival was an AFP level greater than
30 ng/mL.²⁹ However, in a multivariate analysis of 345 liver-transplant patients by Toyoda and as­sociates in 2008, no tumor markers were significantly associated with the survival rate.³⁰

In a study by Hsieh and colleagues in 2010, 23% of patients demonstrated normal AFP levels at the time of HCC recurrence; the AFP levels in these patients were initially high. These patients with inconsistent AFP levels had a longer recurrence interval but a worse recurrence survival rate than other patients. This may be attributable to a delay in the detection of HCC recurrence.³¹ In a study done by Ito and colleagues in 2007, an AFP level > 400 ng/mL and a protein induced by vitamin K absence or antagonist II level > 400 mAU/mL were significant predictors of a higher recurrence rate.²¹

In our study, the median value of AFP in the non­recurrence group was 10.6 ng/mL; in the recurrence group, the median value was 19.54 ng/mL. Stepwise multivariate logistic regression analysis shows that both decreasing age (< 52 years) and AFP levels
(< 88 ng/mL) in patients preoperatively within the Milan criteria are the most sensitive dis­criminators for predicting patients with increased survival. This supports the theory that higher pretransplant levels of AFP increase the risk of recurrence.

Preoperative ablative therapy
The progression of HCC can sometimes be unpredictable. A study that used expanded tumor criteria showed higher 5-year survival (93.8% vs 80.6%; P = .05) in patients who received neoadjuvant treatment than in those who did not receive any treatment.³²

Mazzaferro reported no dropouts in 50 patients within the Milan criteria treated with RFA.¹⁸ In addition, some studies have reported no dropouts in patients within the Milan criteria treated using TACE and a short wait time (178 days), whereas others have documented a probability of dropout of 15% at 6 months and 25% at 12 months. The cumulative results of previous studies show that RFA achieves the highest rates of complete necrosis, at 12% to 55%; for comparison, TACE has a rate of 22% to 29%. Complete necrosis is best achieved with percu­taneous ablation in tumors < 3 cm in diameter.³² Barakat and associates show that the viable tumor burden at the time of transplant, not the initial presenting tumor burden, ultimately determines the oncologic outcome.³³

At our center, we perform only LDLT, so the wait time is typically short. However, when the expected delay is over 1 month, we perform ablative therapy. This applied to 20 patients (33.3%) in our study: 9 (15%) underwent RFA, 8 (13.3%) underwent TACE, 2 (3.3%) underwent combined RFA and TACE, and 1 patient (1.7%) underwent ethanol injection. Of those patients, 4 developed recurrence, with a mean recurrence-free survival of 37 months (range, 3-78 months) and a mean overall survival of 51 months (range, 6-84 months).

Immunosuppression
Immunosuppression may increase the likelihood of HCC recurrence after liver transplant; however, there are no published randomized trials that have investigated this association.^34,35 Tacrolimus, a calcineurin inhibitor, promotes cell-cycle progression by increasing cyclin dependent kinase 4 activity and is thus linked to increased tumor recurrence. Encouraging results from a retrospective comparison of patients with HCC treated with sirolimus versus calcineurin inhibitors showed a survival benefit after transplant without any difference in the incidence of major complications.³⁴ All of our patients with recurrence were taking tacrolimus; however, we are currently trying sirolimus- and everolimus-based protocols for HCC.

Conclusions

We believe that cirrhotic patients with HCC but without extrahepatic disease should be candidates for liver transplant whenever possible. Although the Milan criteria are used as the standard criteria for selecting patients with HCC eligible for LDLT, the criteria seem to be too restrictive. We demonstrate that patients with a single tumor ≤ 6 cm, or multiple lesions with a total tumor burden ≤ 8 cm, have no significant difference in survival when compared with patients within the Milan criteria.

References:

1. Parkin DM, Bray F, Ferlay J, Pisani P. Global cancer statistics, 2002. CA Cancer J Clin. 2005;55(2):74-108.
   CrossRef - PubMed
   
2. Velázquez RF, Rodríguez M, Navascués CA, et al. Prospective analysis of risk factors for hepatocellular carcinoma in patients with liver cirrhosis. Hepatology. 2003;37(3):520-527.
   CrossRef - PubMed
   
3. Takamatsu S, Noguchi N, Kudoh A, et al. Influence of risk factors for metabolic syndrome and non-alcoholic fatty liver disease on the progression and prognosis of hepatocellular carcinoma. Hepatogastroenterology. 2008;55(82-83):609-614.
   PubMed
   
4. Arafa N, El Hoseiny M, Rekacewicz C, et al. Changing pattern of hepatitis C virus spread in rural areas of Egypt. J Hepatol. 2005;43(3):418-424.
   CrossRef - PubMed
   
5. el-Zayadi AR, Badran HM, Barakat EM, et al. Hepatocellular carcinoma in Egypt: a single center study over a decade. World J Gastroenterol. 2005;11(33):5193-5198.
   PubMed
   
6. Befeler AS, Hayashi PH, Di Bisceglie AM. Liver transplantation for hepatocellular carcinoma. Gastroenterology. 2005;128(6):1752-1764.
   CrossRef - PubMed
   
7. Martin AP. Management of hepatocellular carcinoma in the age of liver transplantation. Int J Surg. 2009;7(4):324-329.
   CrossRef - PubMed
   
8. Tsoulfas G, Kawai T, Elias N, et al. Long-term experience with liver transplantation for hepatocellular carcinoma. J Gastroenterol. 2011;46(2):249-256.
   CrossRef - PubMed
   
9. Mazzaferro V, Regalia E, Doci R, et al. Liver transplantation for the treatment of small hepatocellular carcinomas in patients with cirrhosis. N Engl J Med. 1996;334(11):693-699.
   CrossRef - PubMed
   
10. Yao FY, Ferrell L, Bass NM, et al. Liver transplantation for hepatocellular carcinoma: expansion of the tumor size limits does not adversely impact survival. Hepatology. 2001;33(6):1394-1403.
    CrossRef - PubMed
    
11. Yao FY, Xiao L, Bass NM, Kerlan R, Ascher NL, Roberts JP. Liver transplantation for hepatocellular carcinoma: validation of the UCSF-expanded criteria based on preoperative imaging. Am J Transplant. 2007;7(11):2587-2596.
    CrossRef - PubMed
    
12. Duffy JP, Vardanian A, Benjamin E, et al. Liver transplantation criteria for hepatocellular carcinoma should be expanded: a 22-year experience with 467 patients at UCLA. Ann Surg. 2007;246(3):502-509; discussion 509-511.
    CrossRef - PubMed
    
13. Mazzaferro V. Results of liver transplantation: with or without Milan criteria? Liver Transpl. 2007;13(11 Suppl 2):S44-S47.
    CrossRef - PubMed
    
14. Zheng SS, Xu X, Wu J, et al. Liver transplantation for hepatocellular carcinoma: Hangzhou experiences. Transplantation. 2008;85(12):1726-1732.
    CrossRef - PubMed
    
15. Muscari F, Foppa B, Kamar N, Peron JM, Selves J, Suc B. Liberal selection criteria for liver transplantation for hepatocellular carcinoma. Br J Surg. 2009;96(7):785-791.
    CrossRef - PubMed
    
16. Fan J, Yang GS, Fu ZR, et al. Liver transplantation outcomes in 1,078 hepatocellular carcinoma patients: a multi-center experience in Shanghai, China. J Cancer Res Clin Oncol. 2009;135(10):1403-1412.
    CrossRef - PubMed
    
17. Yao FY, Roberts JP. Applying expanded criteria to liver transplantation for hepatocellular carcinoma: too much too soon, or is now the time? Liver Transpl. 2004;10(7):919-921.
    CrossRef - PubMed
    
18. Mazzaferro V, Llovet JM, Miceli R, et al; Metroticket Investigator Study Group. Predicting survival after liver transplantation in patients with hepatocellular carcinoma beyond the Milan criteria: a retrospective, exploratory analysis. Lancet Oncol. 2009;10(1):35-43.
    CrossRef - PubMed
    
19. Hwang S, Lee SG, Joh JW, Suh KS, Kim DG. Liver transplantation for adult patients with hepatocellular carcinoma in Korea: comparison between cadaveric donor and living donor liver transplantations. Liver Transpl. 2005;11(10):1265-1272.
    CrossRef - PubMed
    
20. Zimmerman MA, Ghobrial RM, Tong MJ, et al. Recurrence of hepatocellular carcinoma following liver transplantation: a review of preoperative and postoperative prognostic indicators. Arch Surg. 2008;143(2):182-188.
    CrossRef - PubMed
    
21. Ito T, Takada Y, Ueda M, et al. Expansion of selection criteria for patients with hepatocellular carcinoma in living donor liver transplantation. Liver Transpl. 2007;13(12):1637-1644.
    CrossRef - PubMed
    
22. Germani G, Gurusamy K, Garcovich M, et al. Which matters most: number of tumors, size of the largest tumor, or total tumor volume? Liver Transpl. 2011;17 (Suppl 2):S58-S66
    CrossRef - PubMed
    
23. Sotiropoulos GC, Molmenti EP, Lösch C, Beckebaum S, Broelsch CE, Lang H. Meta-analysis of tumor recurrence after liver transplantation for hepatocellular carcinoma based on 1,198 cases. Eur J Med Res. 2007;12(10):527-534.
    PubMed
    
24. Lee HH, Joh JW, Park JH, et al. Microvascular tumor embolism: independent prognostic factor after liver transplantation in hepatocellular carcinoma. Transplant Proc. 2005;37(2):1251-1253.
    CrossRef - PubMed
    
25. Eguchi S, Takatsuki M, Hidaka M, at al. Predictor for histological microvascular invasion of hepatocellular carcinoma: a lesson from 229 consecutive cases of curative liver resection. World J Surg. 2010;34(5):1034-1038.
    CrossRef - PubMed
    
26. D’Amico F, Schwartz M, Vitale A, et al. Predicting recurrence after liver transplantation in patients with hepatocellular carcinoma exceeding the up-to-seven criteria. Liver Transpl. 2009;15(10):1278-1287.
    CrossRef - PubMed
    
27. Iwatsuki S, Marsh JW, Starzl TE. Survival after liver transplantation in patients with hepatocellular carcinoma. Princess Takamatsu Symp. 1995;25:271-276.
    PubMed
    
28. Ho MC, Wu YM, Hu RH, et al. Liver transplantation for patients with hepatocellular carcinoma. Transplant Proc. 2004;36(8):2291-2292.
    CrossRef - PubMed
    
29. Bertuzzo VR, Cescon M, Ravaioli M, et al. Analysis of factors affecting recurrence of hepatocellular carcinoma after liver transplantation with a special focus on inflammation markers. Transplantation. 2011;91(11):1279-1285.
    CrossRef - PubMed
    
30. Toyoda H, Kumada T, Kaneoka Y, et al. Prognostic value of pretreatment levels of tumor markers for hepatocellular carcinoma on survival after curative treatment of patients with HCC. J Hepatol. 2008;49(2):223-232.
    CrossRef - PubMed
    
31. Hsieh CB, Chen TW, Chu CM, Chu HC, Yu CP, Chung KP. Is inconsistency of alpha-fetoprotein level a good prognosticator for hepatocellular carcinoma recurrence? World J Gastroenterol. 2010;16(24):3049-3055.
    CrossRef - PubMed
    
32. Yao FY, Kinkhabwala M, LaBerge JM, et al. The impact of pre-operative loco-regional therapy on outcome after liver transplantation for hepatocellular carcinoma. Am J Transplant. 2005;5(4 Pt 1):795-804.
    CrossRef - PubMed
    
33. Barakat O, Wood RP, Ozaki CF, et al. Morphological features of advanced hepatocellular carcinoma as a predictor of downstaging and liver transplantation: an intention-to-treat analysis. Liver Transpl. 2010;16(3):289-299.
    CrossRef - PubMed
    
34. Schlitt HJ, Mornex F, Shaked A, Trotter JF. Immunosuppression and hepatocellular carcinoma. Liver Transpl. 2011;17(Suppl 2);S159-S161.
    CrossRef - PubMed
    
35. Zarrinpar A, Kaldas F, Busuttil RW. Liver transplantation for hepatocellular carcinoma: an update. Hepatobiliary Pancreat Dis Int. 2011;10(3):234-242.
    CrossRef - PubMed