Long-Term Outcomes of Combined Hepatocellular Carcinoma-Cholangiocarcinoma After Liver Transplantation in Patients with or without Concurrent Hepatocellular Carcinoma

Introduction

Generally, primary liver malignancies are categorized as hepatocellular carcinoma (HCC) or intrahepatic cholangiocarcinoma (ICC). In addition, combined hepatocellular carcinoma-cholangiocarcinoma (CHC), a rare subtype, exhibits histological features of both. Because of its rarity, CHC is frequently misdiagnosed as HCC, and often identified only upon histological examination of resected specimens. Classification of CHC has undergone 4 major revisions since its initial description in 1949, with the most recent update in 2019 [1–6]. The prognosis for CHC remains poor, largely due to high recurrence rates despite surgical resection, systemic therapy, or even liver transplantation (LT). Consequently, CHC is historically considered an unfavorable indication for LT [7,8].

Nonetheless, some patients originally listed for LT based on a clinical diagnosis of HCC were later found to have CHC upon histopathological examination of the explanted livers [7,8]. These unexpected diagnoses have prompted critical discussions regarding post-transplant outcomes and appropriate management strategies for CHC in the LT setting.

Recent advances in molecular oncology support the cancer stem cell hypothesis, which suggests that primary liver malignancies, including HCC, ICC, and CHC, originate from hepatic progenitor cells (HPCs) with the potential to differentiate into both hepatocytes and cholangiocytes [6]. In cirrhotic livers, CHC can either present as a distinct tumor type, or coexist with HCC or ICC, making accurate preoperative diagnosis and therapeutic planning particularly challenging. Despite these complexities, the rarity of CHC means that its incidence and clinic-pathological characteristics in LT recipients remain poorly defined. Furthermore, concurrent diagnoses of ICC, HCC, or CHC in explanted livers complicate post-transplant prognostication and management [9]. Notably, CHC is associated with worse post-transplant survival outcomes than HCC [7,8].

The aim of this study was to assess the long-term outcomes of 60 patients who were pathologically diagnosed with CHC, with or without coexisting HCC, based on histological evaluation of explanted livers following LT. In addition, it sought to propose optimized post-transplant surveillance strategies to support cost-effective, long-term management tailored to this distinct patient population.

Material and Methods

PATIENT SELECTION:

This retrospective observational study analyzed a single-arm cohort from a high-volume LT center. A thorough review of the institutional LT database was performed to identify patients in whom CHC was confirmed by histopathological evaluation of explanted livers. Between January 2000 and December 2022, 60 patients with CHC were identified; CHC was present either as a solitary primary tumor or coexisting with HCC. Cases involving concurrent ICC were excluded from the study. During the 23-year period, a total of 6985 adult patients underwent primary LT, with CHC comprising approximately 0.9% of all adult LT cases.

The medical records of all eligible patients were reviewed retrospectively. Follow-up data were collected up to July 2025 or until the time of death, utilizing both institutional medical records and data from the National Health Insurance Service. The study protocol was approved by the Institutional Review Board of our institution (IRB No. 2025-0967). Due to the retrospective design, the requirement for informed consent was waived. All procedures adhered to the ethical principles of the Declaration of Helsinki, as revised in 2013.

PRETRANSPLANT EVALUATION:

Patients diagnosed with HCC or other liver malignancies underwent comprehensive screening prior to LT. This assessment comprised imaging studies such as abdominal-pelvic and thoracic CT scans, abdominal magnetic resonance imaging (MRI), and 18F-fluorodeoxyglucose positron emission tomography. Additionally, upper-gastrointestinal endoscopy and colonoscopy or sigmoidoscopy were performed. The pretransplant evaluation adhered to established guidelines, ensuring thorough cancer screening and malignancy risk assessment as outlined in prior authoritative publications [7,9–11].

TUMOR STAGING AND PATHOLOGICAL CLASSIFICATION:

For this study, tumor staging of CHC was approximated retrospectively using the 8th edition of the American Joint Committee on Cancer (AJCC) staging system for HCC [12].

Given that the pathological classification criteria for CHC evolved substantially over time, with major updates in 1985, 2010, and 2019 [2–4], consistent retrospective application of the most recent classification was not feasible; thus, histological sub-classification was not part of the analysis.

POST-TRANSPLANT IMMUNOSUPPRESSIVE PROTOCOLS:

Immunosuppressive strategies for LT recipients with existing malignancies were implemented in accordance with institutional guidelines, as previously outlined [13]. The conventional regimens primarily included interleukin-2 receptor antagonists, calcineurin inhibitors administered intravenously or orally, and corticosteroids. In cases where patients experienced adverse reactions to calcineurin inhibitors, mycophenolate mofetil was introduced either as an adjunct or an alternative to bolster immunosuppression. Additionally, selected patients received mammalian target of rapamycin inhibitors, particularly for managing CHC or HCC recurrence, new or de novo malignancies, or in the presence of compromised renal function.

POST-TRANSPLANT MALIGNANCY SURVEILLANCE:

At our institution, LT recipients undergo a systematic surveillance program designed to detect malignancies early. This protocol includes routine chest radiographs, abdomino-pelvic and thoracic CT scans, endoscopic examinations, tumor marker evaluations, and screening for breast and cervical cancers. CT imaging is performed every 6 months during the first 3 years after transplant, annually for the subsequent 2 years, and biennially thereafter. Patients identified as having a higher risk of cancer receive more intensive monitoring, particularly during the first 2 years following transplantation. Management of tumor recurrence (TR) adheres to established treatment guidelines for post-transplant hepatic malignancies [7,9,11,13].

STATISTICAL ANALYSIS:

Quantitative variables are presented as the median and range, or as the mean and standard deviation, depending on the data distribution. Survival outcomes, including TR and overall survival (OS), were analyzed using the Kaplan-Meier method, with intergroup comparisons assessed by the log-rank test. Multivariate analysis was conducted using the Cox proportional hazards regression model, with results reported as hazard ratios along with 95% confidence intervals. A p-value of <0.05 was considered significant. All statistical analyses were performed using SPSS software (version 22; IBM Corp., Armonk, NY, USA) and MedCalc (version 23.2.1; MedCalc Software Ltd., Ostend, Belgium).

Results

CLINICOPATHOLOGICAL FEATURES:

The clinicopathological characteristics of the 60 LT recipients diagnosed with CHC are summarized in Table 1. The mean age at transplantation was 55.3±7.0 years, and the majority were male (n=51, 85.0%). The underlying liver disease was predominantly hepatitis B virus (HBV) infection (n=53, 88.3%), followed by alcoholic liver disease (n=6, 10.0%) and other causes of cirrhosis (n=1, 1.7%). The average Model for End-Stage Liver Disease score at the time of transplantation was 12.3±5.8.

Pretransplant diagnosis indicated that 59 of the 60 patients had HCC. Only 1 patient was strongly suspected to have CHC prior to LT, having undergone hepatic resection for CHC 1 year earlier. Before transplantation, 49 patients received locoregional or surgical treatments, including transcatheter arterial chemoembolization (TACE; n=41), radiofrequency ablation (RFA; n=5), and hepatic resection for HCC (n=2) and CHC (n=1). The remaining 11 patients (18.3%) did not receive any HCC-directed treatment before transplantation.

Measurement of pretransplant tumor marker levels revealed considerable variability. For alpha-fetoprotein (AFP; institutional reference ≤7.5 ng/mL), the mean and median values were 250.9±1258.5 ng/mL and 16.1 ng/mL, respectively, with a range of 1.1–9734 ng/mL. Proteins induced by vitamin K absence or antagonist-II (PIVKA-II; reference ≤40 mAU/mL) had a mean level of 109.1±238.9 mAU/mL, with a median of 29 mAU/mL (range, 5–1136 mAU/mL). Carbohydrate antigen 19-9 (CA19-9; reference ≤37 U/mL) levels averaged 23.6±21.1 U/mL, with a median of 16.7 U/mL (range, 3–119 U/mL). Elevated AFP levels were detected in 41 of 60 patients (68.3%), elevated PIVKA-II in 30 of 53 patients (56.6%), and elevated CA19-9 in 4 of 32 patients (12.5%).

In 2 cases (3.3%), LT was performed using deceased-donor whole-liver grafts, and using living-donor liver grafts in 58 cases (96.7%), with 55 of these receiving right liver grafts and 2 undergoing dual-graft implantation. ABO blood group-incompatible transplantation was conducted in 12 recipients (20.0%).

Pathological characteristics are detailed in Table 1. For CHC, the mean and median tumor diameters were 2.5±1.7 cm and 2.0 cm, respectively, ranging from 0.3 to 9.1 cm. The number of CHC lesions was as follows: 1 in 51 patients (85.0%), 2 in 5 (8.3%), and 3 or more in 4 (6.7%). Based on the 8th edition of the AJCC staging system for HCC, CHC tumors were staged as stage IA in 27 patients (45.0%), IB in 19 (31.7%), II in 13 (21.7%), and IIIA in 1 (8.0%).

Viable HCC was co-existent in 23 patients (38.3%). Five patients had a total of 11 liver nodules that showed a complete pathological response following TACE; however, these non-viable lesions were excluded from the analysis. The mean maximum diameter of viable HCC lesions was 2.8±2.7 cm, with a median size of 1.5 cm (range: 0.6–12.8 cm). The number of viable HCC tumors was as follows: 1 in 10 patients, 2 in 8 patients, and 3 or more in 5 patients. Microvascular invasion was observed in 5 cases. According to the 8^th edition AJCC staging system, these concurrent HCCs were classified as stage IA in 7 patients, IB in 2 patients, II in 13 patients, and IIIA in 1 patient.

PATTERNS AND TREATMENT OF TUMOR RECURRENCE:

One patient died due to perioperative complications following LT. During a mean follow-up period of 83.4±70.5 months, TR of any origin (CHC or HCC) was observed in 24 patients (40.0%). The initial sites of recurrence included intra- and extra-abdominal lymph nodes (n=5), the liver graft (n=5), the lungs (n=5), the peritoneum (n=5), bones (n=3), and abdominal muscle (n=1).

Among the 37 patients with CHC alone, 13 (35.1%) experienced TR, and all died during the follow-up period. In 1 case, recurrence was confirmed histologically as CHC following pulmonary metastasectomy. Initial treatment for recurrent CHC included systemic chemotherapy (n=7 patients), radiotherapy (n=3), surgical resection (n=1), and no specific intervention (n=2). As the disease progressed, 11 of the 13 patients ultimately received systemic chemotherapy. All 13 patients who experienced TR died due to the disease within 4 years of recurrence.

Among the 23 patients with concurrent HCC, TR of any origin was observed in 11 cases (47.8%), all of whom died within 4 years of recurrence. The exact origin of recurrence, whether from CHC or HCC, could not be determined. Initial treatment strategies included systemic chemotherapy (n=5), TACE (n=3), radiotherapy (n=1), and supportive care (n=2). As the disease progressed, 9 of the 11 patients ultimately received systemic chemotherapy.

TUMOR RECURRENCE AND SURVIVAL OUTCOMES:

Over a follow-up period extending up to 274 months, TR of any origin (CHC or HCC) was observed in 24 recipients (40.0%). A total of 28 patients (46.7%) died, with 24 deaths attributed to TR and 4 to other causes. The cumulative TR rates at 6 months, 1 year, 3 years, 5 years, 10 years, and 20 years were 17.0%, 22.1%, 36.1%, 37.9%, 42.7%, and 42.7%, respectively (Figure 1A). Corresponding OS rates at those time points were 95.0%, 85.0%, 65.0%, 57.7%, 51.3%, and 51.3% (Figure 1B).

When stratified by the presence of concurrent viable HCC, the 1-, 3-, and 5-year all-type TR rates were 19.2%, 33.1%, and 33.1%, respectively, among the 37 recipients with CHC alone; and 27.1%, 41.1%, and 46.5%, respectively, among the 23 recipients with concurrent viable HCC (p=0.228; Figure 2A).

The OS rates at 1, 3, 5, and 10 years were 86.5%, 70.3%, 67.3%, and 60.5%, respectively, in the CHC alone group, compared with 82.6%, 56.2%, 42.1%, and 36.1%, respectively, in those with concurrent viable HCC (p=0.083; Figure 2B).

Among the 37 patients with CHC alone, tumor staging based on the 8th edition AJCC system demonstrated a significant association with both recurrence (p=0.017; Figure 3A) and OS (p=0.038; Figure 3B). In the subgroup of 23 patients with CHC and concurrent viable HCC, AJCC staging of the CHC was significantly associated with all-type recurrence (p=0.007; Figure 4A), but not with OS (p=0.082; Figure 4B). Among 16 patients with early-stage (IA and IB) CHC and concurrent viable HCC, the AJCC staging of the concurrent HCC did not have a statistically significant effect on all-type recurrence (p=0.105; Figure 5A) or OS (p=0.164; Figure 5B).

Post-recurrence survival did not differ significantly between patients with CHC alone and those with concurrent viable HCC (p=0.843; Figure 6). Multivariate analysis incorporating AJCC staging for both CHC and concurrent HCC identified CHC stage as an independent predictor of both all-type recurrence and OS, whereas the concurrent HCC stage did not have a significant impact on either outcome (Table 2).

TUMOR RECURRENCE AND SURVIVAL OUTCOMES IN PATIENTS WITH VERY EARLY-STAGE CHC:

Among 17 recipients with very early-stage CHC, defined as a single lesion ≤2 cm (AJCC stage IA) without concurrent HCC, the cumulative TR rates at 1, 3, 5, and 10 years were 5.9%, 17.6%, 17.6%, and 17.6%, respectively (Figure 7A). The corresponding OS rates were 94.1% at 1 year, and 82.4% at 3, 5, and 10 years (Figure 7B).

Discussion

CHC is an uncommon primary liver malignancy. Data from the Surveillance, Epidemiology, and End Results (SEER) program indicate that between 1988 and 2009, out of 52 825 patients with HCC and 7181 patients with ICC, only 465 were diagnosed with CHC (approximately 0.8% of cases) [14]. At our institution, CHC constitutes 5.8% of surgically-resected primary liver tumors [15]. Published studies report that CHC has variable incidences, ranging from 0.8% to 14.3% of primary liver malignancies, reflecting considerable heterogeneity across cohorts [16–18].

Analysis of the United Network for Organ Sharing (UNOS) database from 1994 to 2013 identified 4049 LT recipients with primary liver malignancies, including 94 cases of CHC, 3515 cases of HCC, and 440 cases of ICC, indicating that CHC accounts for approximately 2.3% of primary liver cancers in LT recipients [19]. Similarly, data from the National Cancer Data Base (NCDB) between 2004 and 2012 reported 106 103 LTs for primary malignancies, with 1141 cases of CHC, 90 499 of HCC, and 14 463 of ICC, yielding a CHC incidence of 1.1% [20]. In our previous studies, the incidence of CHC among LT recipients was 0.7% (15 of 2137 patients) [21] and 1.0% (32 of 3103 patients) [7].

Several theories have been proposed to explain the carcinogenesis of CHC. It is suggested that the cholangiocarcinoma components within CHC do not simply arise from conventional HCC, but rather originate from HPCs capable of dual differentiation [22,23]. This shared HPC origin hypothesis was incorporated into the 2010 WHO classification of liver tumors [3]. Although 4 histologic classifications of CHC have been proposed historically [1–4], none have consistently demonstrated prognostic relevance [15,24–26]. Consequently, this study did not undertake retrospective reclassification of cases according to the updated 2019 WHO criteria, as re-analysis through immunohistochemical staining of the archived specimens was not feasible.

Concurrent viable HCC was detected in 38.3% of patients. Given that these patients had been diagnosed with HCC prior to LT, it may be more appropriate to classify them as HCC with concurrent CHC. Accounting for an additional 5 patients who achieved a complete pathological response following pretransplant locoregional treatment, the actual prevalence of concurrent HCC in real-world settings may be even higher. This elevated rate aligns with the previously mentioned hypothesis of a shared HPC origin. Our analysis revealed that the presence of concurrent viable HCC did not impact long-term TR or OS of CHC patients significantly. Similarly, post-recurrence survival was comparable between patients with and without concurrent HCC. Multivariate analysis further confirmed that TR and OS were affected by the stage of CHC rather than the stage of concurrent HCC. These findings suggest that the post-LT prognosis of patients with CHC is determined predominantly by the CHC itself, rather than by concurrent viable HCC.

We also found that 88.3% of patients were diagnosed with HBV infection. Published reports indicate that 58–93% of patients with CHC have a history of HBV and/or hepatitis C virus infection [25–29]. These observations support the notion that chronic viral hepatitis plays a significant role in the pathogenesis of CHC, paralleling its established association with conventional HCC [30]. Recent comprehensive genomic analyses identified numerous novel mutational events in ICC and CHC that are linked to integration of HBV DNA into the host genome, offering deeper biological and clinical insights into HBV-driven development of ICC and CHC [31].

At our institution, CHC is currently not considered a standard indication for either primary or salvage LT, primarily due to its aggressive tumor biology and high post-transplant recurrence rates. As a result, most CHC cases were diagnosed incidentally in explanted livers after LT. Only 1 patient in this cohort underwent salvage LT for recurrent CHC; however, the patient died due to progressive multifocal TR [32]. The 10-year all-type TR and overall OS rates were 42.7% and 51.3%, respectively, with all patients experiencing recurrence dying within 4 years of onset. These findings highlight the need to re-evaluate and clearly define the indications for LT in patients with CHC, rather than universally regarding it as a contraindication.

Typically, ICC is more aggressive than CHC, and has long been considered a contraindication for LT. Nevertheless, several multicenter studies reported encouraging post-transplant outcomes for patients with very early-stage ICC, suggesting that LT may be a viable option, under strict selection criteria, for selected cirrhotic patients with presumed very early-stage ICC [33,34]. A similar approach may be extended to CHC. In the present study, among 17 recipients with very early-stage CHC, defined as a solitary lesion ≤2 cm without concurrent HCC (AJCC 8th edition stage IA), the 10-year TR and OS rates were 17.6% and 82.4%, respectively. These favorable long-term outcomes support the consideration of LT in patients with cirrhosis and suspected very early-stage CHC [22].

Accurate pretransplant diagnosis of CHC remains challenging. Because of its rarity, limited information is available regarding risk factors and imaging characteristics. CHC often shares radiologic features with HCC and ICC, making differentiation difficult. Classic imaging findings such as characteristic enhancement patterns or biliary ductal dilatation are not observed consistently. While serum tumor markers like AFP, PIVKA-II, and CA 19-9 can provide diagnostic clues, particularly when discordant or markedly elevated, they are not definitive. Given the critical role of imaging in LT candidacy, heightened awareness of CHC among radiologists and clinicians is essential for appropriate decision-making [35]. In cases where CHC is suspected, percutaneous liver biopsy should be considered for patients on the LT waiting list, particularly since cases with large CHC or ICC lesions are typically excluded from LT due to their high recurrence risk and poor outcomes. Conversely, and as suggested earlier, LT may be cautiously considered for cirrhotic patients with presumed very early-stage CHC or ICC.

This study is subject to several limitations. It is a retrospective analysis from a single institution located in an HBV-endemic area and involved a relatively small patient cohort, which may limit the generalizability of the findings. As with all studies of this nature, inherent biases and confounding factors cannot be entirely excluded. To more accurately delineate the clinicopathological characteristics and long-term outcomes following LT, broader multicenter and geographically diverse studies are needed. Nonetheless, a notable strength of this study is the comprehensive follow-up, with complete survival data available for all included patients.

Conclusions

CHC is often identified incidentally in explanted livers, often from patients with a history of HCC treatment, with over one-third exhibiting concurrent viable HCC. Post-transplant outcomes for CHC patients are generally unfavorable because of the high risk of TR, except in those with very early-stage disease. Given that the majority of recurrences occur within the first 5 years after transplantation, intensive surveillance is crucial during this high-risk period. Importantly, patients with very early-stage CHC may be considered appropriate candidates for LT.