Author Affiliations: Center for Liver Cancer, Research Institute and Hospital, National Cancer Center, Goyang-si, Gyeonggi-do, Republic of Korea (Lee SD, Park SJ, Han SS, Kim SH, Kim YK, Lee SA, Ko YH and Hong EK)

Corresponding Author: Sang-Jae Park, MD, PhD, Center for Liver Cancer, Research Institute and Hospital, National Cancer Center, 323 Ilsan-ro, Ilsandong-gu, Goyang-si, Gyeonggi-do, 410-769, Republic of Korea (Tel: +82-31-920-1640; Email: spark@ncc.re.kr)

 

© 2014, Hepatobiliary Pancreat Dis Int. All rights reserved.

doi: 10.1016/S1499-3872(14)60275-7

Published online July 17, 2014.

 

Contributors: LSD analyzed the data and wrote the paper. PSJ proposed the study and performed the research. HSS and KSH performed research and contributed to the design of study. KYK, LSA, KYH and HEK contributed to the design and interpretation of the study and to further draft. PSJ is the guarantor.

Funding: None.

Ethical approval: This study was approved by the institutional review board.

Competing interest: No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.

BACKGROUND: Combined hepatocellular carcinoma and cholangiocarcinoma (cHCC-CC) is a rare subtype of primary liver cancer consisting of both hepatocellular carcinoma (HCC) and cholangiocarcinoma (CC). Because of the rarity of this tumor, its feature is poorly understood. The present study aimed to evaluate the clinicopathological features and long-term prognosis of patients with cHCC-CC after surgery and to compare with those of the patients with stage-matched HCC and CC.

 

METHODS: The clinicopathological features of the patients who underwent surgery for cHCC-CC at our center during the period of 2001-2010 were retrospectively analyzed and compared with those of stage-matched HCC and CC patients. Cancer staging was performed according to the AJCC Cancer Staging Manual (6th ed.). Overall survival and disease-free survival were compared among the groups and prognostic factors of cHCC-CC were evaluated.

 

RESULTS: Significant differences were observed in clinicopathological features among 42 patients with cHCC-CC, 90 patients with HCC and 45 patients with CC. Similar to HCC patients, cHCC-CC patients had frequent hepatitis B virus antigen positivity, microscopic vessel invasion, cirrhosis and high level of serum alpha-fetoprotein. Similar to CC patients, cHCC-CC patients showed increased bile duct invasion and decreased capsule. The 1-, 3-, and 5-year overall survival and disease-free survival of patients with cHCC-CC were not significantly different from those with stage-matched patients with CC; but significantly poorer than those with HCC. In subanalysis of patients with stage II, the overall survival in patients with cHCC-CC or CC was significantly poorer than that in patients with HCC. We did not find the difference in patients with other stages. Univariate analysis of overall and disease-free survival of patients with cHCC-CC showed that the vascular invasion and intrahepatic metastasis were the significant predictive factors.

 

CONCLUSION: Patients with cHCC-CC showed similar clinicopathological features as those with HCC or CC, and patients with cHCC-CC or CC had a poorer prognosis compared with those with HCC, especially at matched stage II.

 

(Hepatobiliary Pancreat Dis Int 2014;13:594-601)

 

KEY WORDS: hepatocellular carcinoma; cholangiocarcinoma; stage; prognosis

Combined hepatocellular carcinoma and cholangiocarcinoma (cHCC-CC) is a rare primary liver malignancy that contains histopathological features of both hepatocellular carcinoma (HCC) and cholangiocarcinoma (CC).^[1-4] The incidence of this entity accounts for 0.4%-14.2%.^[2,3,5] In 1949, Allen and Lisa defined cHCC-CC as the intimate intermingling of both HCC and CC components,^[5] and classified cHCC-CC into three types: type A (double cancer; HCC and CC exist at different sites within the same liver), type B (combined type; HCC and CC exist at adjacent sites and mingle with continued growth) and type C (mixed type; HCC and CC components are combined within the same mass). However, in a recent WHO publication,^[6] cHCC-CC was classified into classical type which is similar with type C by Allen and Lisa, and subtypes with stem-cell features and cells positive for keratins 7 and 19, nuclear cell adhesion molecule, KIT and/or epithelial cell adhesion molecule.^[6] To date, the classifications for cHCC-CC have not been well established.

 

Furthermore, the demographic, pathological features and prognoses of cHCC-CC remain ill-defined and are varied because of its low prevalence. For example, prognostic risk factors were investigated in few studies.^[7-12] The clinical features of cHCC-CC were more similar to those of HCC rather than CC.^[7-12] Patients with cHCC-CC commonly had liver cirrhosis and were positive for viral markers such as HBV and HCV. In contrast, molecular analysis of a small series of samples showed that cHCC-CC is genetically closer to CC rather than HCC.^[13] The 5-year overall survival rate of the patients varied from 0% to 50%,^{[7, 14-16]} which is similar to or worse than that of patients with CC.^{[12, 17]} The recurrence pattern of cHCC-CC was similar to that of CC rather than HCC.^[4]

 

However, the prognosis comparisons of cHCC-CC with HCC and CC were inconsistent because stage-matched analysis of prognosis was not performed. Therefore, we attempted to compare the prognosis and clinicopathological features of cHCC-CC patients with stage-matched HCC and CC patients (based on the AJCC Cancer Staging Manual, 6th ed.^[18]). Also, we analyzed prognostic factors in a relatively large number of cHCC-CC cases.

 

 

Of the 932 patients who underwent hepatectomy for primary liver tumor from January 2001 to November 2010 at National Cancer Center, Republic of Korea, 45 were diagnosed with cHCC-CC, 38 of them were classified as type C by Allen and Lisa,^[5] whereas three and four were type A and type B, respectively. We excluded three patients with type A cHCC-CC. Therefore, 42 patients were enrolled in this study. The median follow-up period was 21.6 months (range 2.1-100.1). During the same period, 791 HCC and 96 CC operations were performed in our institute. All intrahepatic CC patients were of mass-forming macroscopic type. At first, we tried to enroll 2-fold more HCC and CC patients (90 cases) than cHCC-CC patients (45 cases) to do stage-matched comparative analysis, however, the number of resected CC patients was small that we could only include 45 CC patients. Therefore, in this study, 42 cHCC-CC, 90 HCC, and 45 CC patients were evaluated. All the patients with cHCC-CC, HCC, and CC were consistent with Child-Turcotte-Pugh (CTP) classification A.

 

The medical records of 42 cHCC-CC, 90 HCC and 45 CC patients were reviewed for clinicopathological information, including age, gender, viral markers, serum alpha-fetoprotein (AFP), carcinoembryogenic antigen (CEA), carbohydrate antigen 19-9 (CA19-9), preoperative computed tomography (CT), magnetic resonance imaging (MRI), and pathological reports. Three-phase dynamic CT was performed as a routine preoperative imaging tool for diagnosis and staging work-up. Additional positron emission tomography (PET) or biopsies was performed in some patients. We performed R0 hepatectomy for all patients. Unlike CC patients, patients with HCC did not undergo routine dissection of lymph nodes. Pathologic data included operation type, tumor size and number, presence of capsules, micro- and macro-vascular invasion, bile duct invasion, intrahepatic metastasis, cirrhosis, resection margin, and AJCC stage. The pathologic diagnosis of the patients was based on a combination of histology and immunohistochemistry. cHCC-CC was seen as a classical type (Fig. 1). The biliary component was usually a typical adenocarcinoma, often accompanied by abundant stromas. Mucin could be demonstrated histochemically. Keratins 7 and 19 were usually highlighted by immunostaining. The hepatocyte component was defined as trabecular growth with bile production, prominent nucleoli, and hyaline bodies. Immunohistochemical staining including HepPar1 or AFP was performed to support the diagnosis of HCC. One pathologist reviewed all cHCC-CC patients to categorize the dominant type into HCC or CC. The clinicopathological characteristics of cHCC-CC patients were compared with those of patients with HCC and CC. We also compared the overall and disease-free survival of patients with cHCC-CC, HCC and CC by stages. We analyzed the prognostic factors for the overall and disease-free survival of patients with cHCC-CC. And recurrence patterns and management were also investigated in patients with cHCC-CC.

 

Statistical analyses were performed using SAS version 9.1.3 for Windows (SAS institute, Cary, NC). Clinical and pathological variables were analyzed using the Chi-square test or Fisher's exact test and Student's t test, depending on the normality of the distribution. Overall survival curves and disease-free survival curves were plotted using the Kaplan-Meier method and curves were compared using the log-rank test. A P value of <0.05 was considered statistically significant.

 

 

Forty-two cHCC-CC patients were compared with 90 patients with stage-matched HCC and 45 patients with CC. Thirty-two of the 42 patients with cHCC-CC were male and median age was 54.2 years. No significant difference was seen in gender ratio among the 3 groups and nor significant difference in age between the cHCC-CC and HCC groups. The CC patients were significantly older than other two groups. The number of patients with infection of HBV was significantly larger in the cHCC-CC and HCC groups than in the CC group. The preoperative AFP level was significantly higher in the cHCC-CC and HCC groups than in the CC group. However, the CA19-9 level was significantly lower in the cHCC-CC and HCC groups than in the CC group. The preoperative CEA level was similar among the 3 groups. The accuracy of CT diagnosis before surgery for the cHCC-CC, HCC, and CC groups was 7.1%, 97.8%, and 68.9%, respectively. The accuracy of MRI diagnosis was 5.7%, 97.7%, and 65.4%, respectively (Table 1).

 

There was no significant difference in operation type among the 3 groups. However, the CC group underwent major hepatectomy more frequently than other groups. Tumor size, macroscopic vessel invasion, intrahepatic metastasis, resection margin and AJCC stage were not significantly different among the groups. However, the cHCC-CC group demonstrated microscopic vessel invasion and cirrhosis more significantly than the CC group (P=0.043 and <0.001, respectively). Capsule formation and bile duct invasion in the cHCC-CC group were observed between the HCC and the CC groups (Table 2).

 

The mean survival of the cHCC-CC group was 61.9 months and the 1-, 3-, and 5-year overall survival rates were 80.2%, 61.3%, and 54.1%, respectively, which were significantly lower than those of the HCC group (P=0.046), but similar to those of the CC group (P=0.186, Fig. 2A). The 1-, 3-, and 5-year disease-free survival rates of the cHCC-CC group were 46.5%, 32.5%, and 32.5% respectively, which were significantly lower than those of the HCC group (P=0.038), but no difference was seen between the cHCC-CC and CC groups (P=0.242; Fig. 2B). In stage I patients, the mean overall survival was significantly different among the groups (cHCC-CC vs CC vs HCC; 71.7 vs 61.2 vs 95.9 months, P=0.030). However, the cHCC-CC group did not show significant difference in survival compared with the HCC and CC groups (cHCC-CC vs HCC, P=0.281; cHCC-CC vs CC, P=0.310). In stage II patients, the mean overall survival of the cHCC-CC, HCC and CC groups was 59.5, 38.0 and 71.2 months, respectively. The overall survival of the cHCC-CC group was significantly lower than that of the HCC group (P=0.047), but there was no significant difference between the cHCC-CC and CC groups (P=0.279). Furthermore, stage III patients showed similar overall and disease-free survivals among the groups (Fig. 3).

 

Univariate analysis showed that vascular invasion and intrahepatic metastasis were the predictive factors of lower overall survival in patients with cHCC-CC. CEA level, vascular invasion, and intrahepatic metastasis were the significant predictive factors for disease-free survival in cHCC-CC patients. Immunohistochemistry and histology showed that among 42 patients with cHCC-CC, 18 patients were HCC dominant and 24 were CC dominant. However, cell type domination did not affect the overall survival and disease-free survival (Table 3).

 

Tumor recurrence occurred in 27 of the 42 cHCC-CC patients. The median time to recurrence was 4.9 months (range 0.9-39.2). Sixteen of the 27 patients had tumor recurrence at the extrahepatic site. Lymph node metastasis was shown in 6 patients, peritoneal seeding in 6, bone metastasis in 2 and lung metastasis in 2. The management of tumor recurrence was varied (Table 4). Intrahepatic recurrence was treated with resection, transcatheter arterial chemoembolization, radiofrequency ablation or radiation therapy. Extrahepatic recurrence was treated with chemotherapy and radiation therapy. The incidences of the patients with CC, intrahepatic, extrahepatic or both were 36.4%, 45.5%, and 18.2%, respectively. And the incidences of the patients with HCC, intrahepatic, extrahepatic or both were 68.5%, 22.2%, 9.3%, respectively. The recurrence pattern of cHCC-CC was similar to that of CC.

 

 

cHCC-CC is a rare type of primary liver tumor, accounting for 0.4%-14.2%.^{[2, 3, 5, 12, 19]} In the present study we observed 42 patients with cHCC-CC out of 932 patients who had undergone surgery for primary liver tumors (4.5%). The incidence of cHCC-CC in our study was similar to or lower than what was reported elsewhere. A recent study using a population-based registry^[3] identified a total of 380 patients with cHCC-CC, with an incidence of 0.87% for primary liver tumors, which is consistent with the low incidence observed in the present study. The varied incidences of cHCC-CC are likely due to the obscure definition and exclusion of unresectable cases from different studies. Traditionally, Allen and Lisa classification and Goodman classification were used in practice. By these classifications, only Allen and Lisa type C and Goodman type II tumors contained the two different cell types throughout the tumor, true cHCC-CC tumors. Although some pertained publications only count Allen and Lisa type C as cHCC-CC,^{[2, 10]} other reports either included all three types of cHCC-CC^{[8, 19, 20]} or did not state their criteria for diagnosis and classification.^{[11, 21]} Recent WHO classification^[6] might make the definition more clear; however, its classification has not been easily accepted by clinicians because of complexities including stem-cell feature subtypes.

 

The origin of cHCC-CC cells remained unclear. There are three possibilities: 1) collision (double) tumor of HCC and CC that incidentally coexist in the same liver; 2) subsequent differentiation of HCC or CC into the other tumor type, and 3) cancer is derived from hepatic progenitor cells.^{[11, 22]} The intermingled tumor with HCC and CC elements in a transitional area, like Allen and Lisa type C, is explained by both the second and third hypothesis. Theise et al^[23] demonstrated that the cells morphologically and immunohistochemically resembled hepatic progenitor cells merged with the HCC and CC components and with mature-appearing hepatocytes within some cHCC-CC samples. These data suggested that carcinogenesis of this unique neoplasm may be explained by the malignant transformation of hepatic progenitor cells. These findings identified a histological subtype of cHCC-CC with stem-cell features, which was positive for keratins 7 and 19, nuclear cell adhesion molecule, KIT, and/or epithelial cell adhesion molecule.

 

The clinicopathological features of cHCC-CC are similar to those of HCC or CC. Patients with cHCC-CC and HCC were similar in terms of age at diagnosis, male-to-female ratio, positivity for viral hepatitis, and concomitant liver cirrhosis.^[10,17,24] Furthermore, patients with cHCC-CC had less capsule formation and more lymph node metastasis than those with HCC.^[2,10,12] Serum AFP was elevated in 70%-95% of HCC patients,^[25] which was similar in cHCC-CC patients.^[9,26] In contrast, other studies found that serum AFP was lower in cHCC-CC patients than in HCC patients.^[14,27] In the present stage-matched study, the patterns of positivity for viral infection, AFP level, and liver cirrhosis in cHCC-CC patients were similar in HCC patients. Previous studies^{[15, 16]} demonstrated that serum CEA and CA19-9 markers were higher in cHCC-CC patients as in CC patients. However, our study showed capsule formation and bile duct invasion in cHCC-CC patients, and CA19-9 serum level was lower than that of CC patients and similar to that of HCC patients.

 

Preoperative diagnosis for patients with cHCC-CC is very difficult, because there is no typical pattern of contrast uptake or washout in dynamic CT or MRI scans. However, some studies tried to identify cHCC-CC using imaging modalities and hematological markers.^[28-30] The dominant tumor type histology of cHCC-CC could be diagnosed with these tests, but it usually failed to identify the presence of combined tumor. Therefore, it was suggested that percutaneous fine needle aspiration biopsy should be considered to improve the diagnosis of cHCC-CC when a liver tumor did not show the typical imaging findings of HCC or CC.^[31] In this study, only 7.1% and 5.7% of the patients were correctly diagnosed preoperatively by dynamic CT and MRI respectively.

 

Survival and prognosis of patients with cHCC-CC have not been well established. After resection the median survival rate of the patients ranged from 20 to 47 months.^{[2, 10, 12, 16, 17]} Vascular invasion, lymph node metastasis, and the presence of satellite metastases were significant predictors of poor outcome after resection.^{[10,12, 14, 29]} The prognoses of patients with cHCC-CC were poorer than those of patients with HCC, but better than those of patients with CC.^{[2, 12]} In contrast, Lee et al^[7] reported that cHCC-CC had the poorest prognosis of all primary liver tumors. To date, there has not been a stage-matched comparative study among these three groups. Therefore, it is difficult to compare the survival of the patients with cHCC-CC, HCC and CC, because the survival is dependent on tumor stage including tumor size, multiplicity, vessel invasion, and lymph node metastasis. The present study adopted the AJCC stage system and compared the stage-matched different type of tumors and found that the prognosis of cHCC-CC patients was poorer than that of HCC patients, but similar to that of CC patients. Furthermore, the AJCC stage system helped us to predict the prognosis of cHCC-CC patients. Univariate analysis in our study showed that intrahepatic metastasis was a significant prognostic factor for overall survival and disease-free survival in cHCC-CC patients. Briefly, intrahepatic metastasis is as follows: 1) tumors clearly growing from thrombi of the portal vein; 2) tumors surrounding a large main tumor with multiple satellite nodules; 3) a small solitary tumor near the main tumor that is histologically similar to or less differentiated than the primary tumor. Intrahepatic metastasis strongly reflected invasiveness and was also identified as an important independent indicator for poor prognosis.^[32] Our study found that intrahepatic metastasis significantly correlated with low survival rate and early recurrence. Furthermore, we investigated whether there was a correlation between dominant type (HCC or CC) and prognosis. We hypothesized that the CC dominant type would have a poorer prognosis than the HCC dominant type. Indeed, in this study, the CC dominant type showed the hazard ratio of 2.02 and 1.61 in overall survival and disease-free survival, respectively; however, univariate analysis did not show any significant result. A larger number of cases are necessary to clarify the relationship between cHCC-CC dominant type and survival.

 

Few studies have reported the recurrence after cHCC-CC resection. The tumor recurred frequently at the liver.^[2,10] However, the present study showed that extrahepatic recurrence was commonly seen in lymph nodes. The frequency of lymph node metastases in cHCC-CC patients was comparable to that in CC patients. Therefore, regional nodal groups should be resected during operation. No definitive guidelines are available for the treatment of recurrent cHCC-CC. Although such patients could be treated with various modalities, the median survival after tumor recurrence was only 11.7 months (95% CI 3.1-20.3). In practice, close follow-up and adjuvant chemoradiation therapy after surgery were useful to care the patients with cHCC-CC.

 

This study had some limitations. First, it was limited by its retrospective nature, and selection bias may have influenced outcome even though we enrolled consecutive cases. Moreover, CC patients were not sufficient in this study.

 

In conclusion, the clinical features of patients with cHCC-CC, including viral markers, cirrhosis, and AFP levels, were similar to those of patients with HCC. Pathological features of cHCC-CC patients, including capsule formation and bile duct invasion, showed intermediate malignancy between HCC and CC patients. The overall survival and disease-free survival of cHCC-CC patients were poorer than those of HCC patients and similar to those of CC patients. Especially, in stage II, the overall survival was significantly poorer in cHCC-CC and CC patients than in HCC patients.

 

 

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