Pre-transplant prediction of microvascular invasion of hepatocellular carcinoma

Pre-transplant prediction of microvascular invasion of hepatocellular carcinoma

H Said,a MD; M Bahaa,a MD; M Rady,a MD; M Abdo,a MD; A Abdalaal,a MD; M Fathy,a MD; A Mukhtar,b  MD;

Mohamed Hamdy Attya,a MD; M El-Monayeri,a  MD; S Abdalwahab,a MD; M Shaker,a MD; M Sobhy,a MD; Mohmad Ghareb,a MD;

F Aboulfetouh,h  MD; A Hamza,a MD; M El-Meteini,a MD

a) Ain-Shams  Center for Organ Tansplant (ASCOT), Ain-Shams University, Cairo, Egypt.

b) Wady El-Neel Liver Transplant Unit, Wady El-Neel Hospital, Cairo, Egypt.

Abstract

Introduction: Microvascular invasion {MVl) has been demonstrated to be a strong predictor of tumor recurrence  and poor survival after liver transplantation (LT) and liver resection for HCC.l,2 As MVI cannot be determined preoperatively, it is, therefore, of great importance  to try to identify predictors of MVI prior to LT.

Methods: A retrospective analysis of preoperative and pathological data of 79 consecutive patients who underwent living donor liver transplantation (LDLT) between 2002 and 2009 for HCC was conducted. MVI was defined as pathological evidence of microscsopic  involvement of the vessels (portal vein or hepatic vein) within the peritumoralliver tissue. The chi-square test and Student t test were used for univariate  analysis. Overall survival  and disease-free survival rates were analyzed using Kaplan-Meier estimates.

Results: Patients were divided into two groups. Group I had no MVI and included 55 (70.6%) patients and Group II had MVI and included 24 (30.4%) patients. Recurrence in group II (MVI group) was significantly higher than in group I (25% Vs 4%, P = 0.008).Among the preoperative factors, the tumors beyond Milan criteria, number, size and tumor grade were significant predictors of MVI. MVI  was 6.7% in well differentiated HCC in comparison to 46.8%  in moderately and poorly differentiated HCC, respectively (P=O.002) and was 26% versus 83.3% when tumor number was less than 3 and more than 3, respectively (P=0.009).MVIwas 25.6% in tumors less than 5 em and 71.4% in tumors more than 5 em in size (P=0.02). HCC within Milan criteria  had statistically  significant  lower incidence  of MVI than those beyond Milan criteria (P=0.004).

Conclusion: Microvascular invasion associated with higher HCC recurrence rate. Tumor grade, number and size were useful in predicting MVI before LT for HCC. LT for patients within Milan criteria is  associated with   lower   incidence of  pathologically evident MVI.

Introduction:

Liver transplantation (LTX) is an established therapeutic option in  patients with hepatocellular carcinoma (HCC) and especially in patients with cirrhosis.3 Multiple studies on

liver transplantation (LT) for hepatocellular

carcinoma  (HCC)  have  reported various prognostic determinants of "high-risk pathology" for tumor recurrence and decreased patient survival.4,5 Tumor size, tumor number,

lobar distribution, vascular invasion, tumor differentiation, and alpha-fetoprotein (AFP) levels are among  the most frequently encountered ones.6  Micro vascular  tumor embolism is an independent predictor ofHCC recurrence after liver transplantation. Although LT is a safe and effective treatment for HCC within the Milan criteria, the presence of microvascular tumor embolism at pathologic examination can predict its recurrence.7 The

microscopic vascular invasion detected histologically has  the  similar  prognostic significance to that of the macroscopic vascular invasion detected by gross examination.8 Micro vascular invasion is a good  predictive parameter, but  it  is impossible to  detect preoperatively.9 The objective of this study is to detect possible predictors of micro vascular invasion in patients undergoing LDLT for HCC.

Patients and methods: Patient population:

From January 2002 through  December

2009,79 consecutive patients underwent living donor liver transplantation (LDLT) for HCC at three centers of liver transplantation with the same surgical teams.They include 73 male

and 6 female with a median age of 51 years (range from 37 to 64). Tumors within and beyond Milan criteria were included. Tumors beyond Milan criteria and not responding to down-staging (either with radiological evidence or persistent elevated AFP) were excluded.

Within Milan

LTx

(LAT if LIX is delayed)

Preoperative evaluation:

All tumors were assessed with triphasic computed tomography (triphasic CT) and CT portography to confirm diagnosis ofHCC and to know tumor number, size (largest and total tumor bmden),site,satellite,diffuse or localized type and macro-vascular invasion. Extra­ hepatic assessment included routine bone scan and chest CT.AFP was done routine with other tumor marker esp.CEA and CA19,9. Routine assessment of liver (synthetic function and portal hypertension) and other co-morbidity was done. Child and MELD scoring was calculated for all patients.

Down-staging of all tumors beyond Milan criteria was done routinely with either radiofrequency ablation (RFA), chemo­ embolization (TACE) or both. Reassessment

with triphasic CT and AFP was done after 1 and  3 months  to assess  response. Tumor progression after down-staging (either radiological or persistent elevated AFP) was

considered a  contraindication for transplantation.Tumors within Milan criteria were treated with local ablative therapy as a bridge if transplantation was expected to be delayed Figare(l).

Pat1ent population

Beyond Milan

Figure(1): Protocol of management ofHCC before LDLT. LTx: liver transplantation, LAT: Local Ablative Therapy, RF: Radio.frequency, TACE: Trans Arterial Chemo-Embolization, AFP: Alpha FetoProtein, CT: Computed Tomography.

Operation:

Recipient operation started with exploration of the whole abdomen, cytology from ascetic fluid and complete hilar lymph node dissection for intra-operative pathological assessment to exclude extra-heptaic spread. Two patients had bilar lymph node positive for malignancy and transplantation was aborted.

All patients had a Right Liver Graft (RLG) with a GRWR between 0.8 and 1.2 with no special precaution regarding type and number of   vascular  and   biliary  anastmoses.

Pathological assessment:

All  explants  were   examined histo­ pathologically to conium diagnosis of HCC, accurate  assessment of number,  site, size

(largest and   overall),  satellite,  grade, macroscopic or microscopic vascular invasion. Microscopic vascular invasion was defined as pathological  evidence of   microscopic involvement of the  vessels  (portal  vein or hepatic vein) within the peritumoralliver tissue. Predictors of  micro-vascular invasion: Patients were  divided into  two  groups according to the presence or absence of micro­ vascular invasion histo-pathologically in the explant.  Group  I had no MVI and Group  II had  MVI. Both   groups were   compared regarding pre-operative data including age, sex, etiology of cirrhosis, Child score, MELD score, tumor number, size (largest and overall), within or beyond Milan criteria, AFP and grade of   the   tumor detected  pathologically.

Statistical analysis:

We compared  the demographic, clinical, and tumor characteristics of the 2 groups. The collected data are shown as mean values and standard  deviation. The chi-square test and Student t test were used for univariate analysis of  categorical and  normally distributed

continuous variables respectively. P<0.05 was considered significant. Diagnostic accuracy of predictive risk factors  was evaluated using receiver operating characteristic (ROC) analysis. Overall  survival and disease-free survival rates were analyzed using Kaplan­ Meier estimates with comparisons performed using the log-rank test.

Results:

This study includes  79 patients, 73 male (92.4%)  and 6 female (7.6%). Patients were divided into two groups. Group I had no MVI and included 55 (70.6%) patients and Group II had MVI and included 24 (30.4%) patients. HCV was the most common cause of cirrhosis in both groups (95.8% vs 94.5%). Patients in group I were Child A in 8 patients (14.5%), Child Bin 15 patients (27.3%)   and Child C in 32 patients (58.2%), while in group II two patients (8.3%) were  Child  A, 10 patients (41.7%) were Child Band 12 patients (50%) were Child C.MELD score was nearly similar for both groups Table(l).

Table (1): Demographic and clinical data of patient population.

SD: Standard of deviation, M: Male, F: Female, HCV: Hepatitis C Virus, HBV: Hepatitis B Virus.

Microscopic vascular invasion and recurrence

The follow-up  time ranged from 1 to 104 months. Sixteen patients died in the course of follow-up. The overall mortality was 20.3%. Recurrences occurred in 8 patients (10.13%)

at a mean time of 10 months (range, 6 to 15 months).

Microvascular invasion was detected histo­ pathologically in 24 patients (30.4%). Recurrence of HCC post  LT occurred in 2 patients (4%) in the group of no MVI and in

6 patients (25%)  in the group of MVI and (P=0.008) Figure(2), however, there was no statistical difference in overall survival between

60

so

40

30

20

10

0

NoMVI                    MVI

both groups. There was a difference (with a trend to be significant) between recurrence free survivalbetween both groups Figures(3,4).

•no recurrence

•recurrence

Figure (2): Increased incidence of HCC recurrence with MVI.

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Figure(3):Comparisonofoverallsurvival between group I (no MVI) and group II (withMVI).

Predictors of Microscopic vascular invasion

Table(2)

Univariate analysis revealed that tumour number, size, grade and extension beyond Milan criteria were significantly associated with microscopic vascular invasion Table(2).

Other variables, including sex, age, preoperative hepatic function including Child-Pugh classification  and model of end-stage liver disease (MELD) score and AFP, did not significantly affect incidence of MVI. Tumor number

Tumor number was significantly associated

with higher incidence of MVI. Statistical analysis showing a tumor number of three was

considered as a cutoff value. Microvascular invasion occurn:d in 5 out of 6 patients (83.3%) with tumor number more than 3, while it occurred in 19 out of73 patients (26%) when tumor number was less than 3 (P= 0.009). Tumor size

Overall  tumor  size  was insignificantly

"

UO           !V.OC            40111J           -          aflt           1..     ,21

rnUfTeM-•"''•urvfYal

Figure(4):Recurrence free survival betweenboth groupsshowingtrendsto be significantdifference but still yetnot significant.

related to microscopic vascular invasion (MVI). Forty  six  patients had  single tumor.  In comparison between the incidence ofMVI in group of single tumor, tumor size more than

5 em was significantly associated with MVI (5 out of7 patients- 71.4%) than when tumor size was less than 5 em (10 out of39 patients

- 25.6%) (P= 0.02).

Tumor grade

Eleven patients bad a well ablated tumor, so grade of these tumors could notbe assessed. Micro vascular invasion occurred in 1 of 15 (6.7%) of well differentiated tumors andin22 of 47 (46.8%) patients with moderately  or poorly  differentiated tumors  (P=0.002).

Milan criteria

Fifty five patients were transplanted for

HCC within Milan criteria and 24 patients bad tumors beyond Milan criteria. The incidence of MVI in tumors within  Milan was much lower than in tumors beyond Milan (20% Vs

54%, P= 0.004).

Table (2): Univariate analysis of clinico-pathological factors in the 2 groups.

*: Statistically significant.

Discussion:

Orthotopic liver transplantation {OLT) is

the preferred treatment for selected patients with hepatocellular carcinoma{HCC) and end­ stage liver disease.While transplantation offers the theoretic  advantage of complete tumor excision with removal of the diseased liver, recurrence ofHCC following OLT is the rate­ limiting factor for long-term survival. Several studies have chronicled the actual incidence of recurrent HCC after  transplantation Table(3). Mechanisms of cancer recurrence include the presence of microscopic extrahepatic foci at the time of transplantation. Thus, HCC may resurface in the form of metastatic foci in distant organs, such as the lungs, brain, bone, and in the transplanted

allograft.IO In this study 79 patients were transplanted for HCC within and beyond Milan criteria (with good response to downstaging). Recurrences occurred in 8 patients (10.13%) at a mean time of 10 months (range, 6 to 15 months).

Several clinical variables have been identified that independently influence tumor recurrence and patient survival. Early observations by Iwatsuki  and colleagues, identified lymph node metastasis and vascular invasion of the tumor as significant negative predictors. Subsequent experience has confirmed that both microvascular and macrovascular invasion  portend a worse outcome and correlate with an increased incidence of post-OLT tumor recurrence.10,11

Table (3): HCC recurrence foUowing orthotopic liver transplantation.JO

Microvascular invasion {MVI) has recently been demonstrated to be a very strong predictor of tumor recurrence and poor survival after liver transplantation (LT) and liver resection for HCC.1,2 While major vascular  invasion  can be identified preoperatively in the majority of cases,  microscopic vascular invasion is impossible to rule out before transplantation.16

This study confirmed the relation between recurrence and microvascular invasion. Recurrence ofHCC post LT occurred in 2 out

of 55 patients (4%) in group of no MVI and in 6 out of24 patients (25%) in group ofMVI

{P = 0.008). There was a difference (with a

trend to be significant)  between recurrence free  survival  between  both    groups.

Poorly differentiated HCC have a malignant potential, such as high-frequent micro-vascular invasion even if the tumor size is equal or smaller than 3 em in diameter.17 A recent report by Esnaola indicated a strong association between poor HCC differentiation grade and

presence of  micro-vascular  invasion.18

Moderately and poorly differentiated tumor in this  study  was  associated with  increasing incidence of  MVI  in  comparison to  well differentiated tumors  (46.8%  Vs 6.7%,  P=

0.002), so liver biopsy at the time of ablation

in high risk  patients  for recurrence may be beneficial and need to be studied.

Tumor size and the number ofHCC nodules have been shown to influence patient survival and recurrence.19,20 A previous multivariate analysis from the registry has shown that only tumor size and tumor grade are independent predictors of  outcome.21,22  Postoperative recurrence-free survival was  significantly diminished by tumor differentiation grade, size greater than 5 em, or macro- and microvascular invasion.23,24 In spite of that a lot of works discuss the relation between size and number ofHCC with the incidence of the recurrence; very few data analyze the relation between them and microvascular invasion.

Inthis study, the relation between incidences

of microvascular invasion, tumor number and size  was  studied. Eighty  three  percent of patients with tumor number more than 3 had microvascular invasion, in comparison to twenty  six  percent of patients with  tumor number less than 3 (P= 0.009). Largest tumor size also showed a significant difference in the incidence of  microvascular invasion. Microvascular invasion  occurred in seventy one percent of patients with largest tumor size more than 5 em, in comparison to twenty five percent of patients with largest tumor size less than 5 em (P= 0.02).

Milan criteria were accepted by the United Network of Organ Sharing to guide patient selection for HCC. Significantly increased 5- year survivals of 85% have been achieved in Child class Band Cas the best situation for treatment of small HCC in cirrhotic patients. In other studies, scientists had shown that the Mazzaferro criteria  may be too restrictive; some transplant teams have proposed other staging systems with  expanded criteria.25

In this study Milan criteria still had a lower incidence of MVI.  Microvascular invasion occurred in200/o of tumors within Milan criteria and in 54% of tumors beyond Milan criteria (P= 0.004). We believe that Milan criteria are the  most  safe  criteria but do not  meet  the

increasing  burden of increasing incidence  of

HCC all over the world.

Conclusion:

Tumor grade, number and size are useful in predicting the presence or absence of micro vascular invasion before liver transplantation for HCC. Liver transplantation for patients within Milan  criteria markedly decrease incidence of pathologically evident MVI with expected lower incidence of recurrence. Liver biopsy  at the time  of ablation in high  risk patients for recurrence may be beneficial and need to be studied.

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