Multi-region sampling with paired sample sequencing analyses reveals sub-groups of patients with novel patient-specific dysregulation in Hepatocellular Carcinoma.

BACKGROUND: Conventional differential expression (DE) testing compares the grouped mean value of tumour samples to the grouped mean value of the normal samples, and may miss out dysregulated genes in small subgroup of patients. This is especially so for highly heterogeneous cancer like Hepatocellular Carcinoma (HCC). METHODS: Using multi-region sampled RNA-seq data of 90 patients, we performed patient-specific differential expression testing, together with the patients' matched adjacent normal samples. RESULTS: Comparing the results from conventional DE analysis and patient-specific DE analyses, we show that the conventional DE analysis omits some genes due to high inter-individual variability present in both tumour and normal tissues. Dysregulated genes shared in small subgroup of patients were useful in stratifying patients, and presented differential prognosis. We also showed that the target genes of some of the current targeted agents used in HCC exhibited highly individualistic dysregulation pattern, which may explain the poor response rate. DISCUSSION/CONCLUSION: Our results highlight the importance of identifying patient-specific DE genes, with its potential to provide clinically valuable insights into patient subgroups for applications in precision medicine.

Laparoscopic Central Bisectionectomy Including Resection of the Segment 7 Using the Extrahepatic Glissonean Approach and Hepatic Vein Guidance.

BACKGROUND: Certain variations in liver anatomy can aid in parenchymal-preserving hepatectomy.1,2 Inferior right hepatic vein (IRHV) is an accessory vein in the right side of liver draining segment 6.2 We present a case of 67-year-old man with HBV cirrhosis. One HCC in segment 7 abutting the right hepatic vein (RHV) and another large HCC in segment 8/4a were found. After two sessions of TACE, liver resection was scheduled. Resection of RHV was inevitable to get free margin. Fortunately, a significant IRHV was present, so we could preserve segment 6. Central bisectionectomy with segment 7 resection using the Glissonean pedicle approach, and hepatic vein guided transection was planned.3 METHODS: After placement of trocars, pneumoperitoneum was created. The main surgical steps were: (1) Right anterior Glissonean pedicle control; (2) Parenchymal transection along the umbilical fissure; (3) Transection of the right anterior portal pedicle, middle, and right hepatic vein; (4) Parenchymal transection between segments 5 and 6; and (5) Identification of IRHV and resection of segment 7. RESULTS: The operative time was 330 min, and estimated blood loss was 80 mL. The total intermittent inflow occlusion time was 90 min. The histopathologic diagnosis was well-differentiated HCC. The tumors size of segments 8 and 7 was 4 cm and 2.9 cm, respectively. The resection margin was negative. The patient was discharged uneventfully on postoperative day 5. CONCLUSIONS: The preserved liver parenchyma after hepatectomy demands good vascular inflow and outflow. A large IRHV could be adequate outflow of segment 6, allowing more distinct operations.

Ultrasound screening for cholangiocarcinoma could detect premalignant lesions and early-stage diseases with survival benefits: a population-based prospective study of 4,225 subjects in an endemic area.

BACKGROUND: Thailand has a high incidence of cholangiocarcinoma (CCA), particularly in the north and northeastern regions. Most CCA patients come at a late, unresectable stage and presently no optimal screening test for CCA has been established. We determined the prevalence of CCA in a remote northern village and explored if screening could lead to early detection and survival benefits. METHODS: A 5-year population-based study was started in October, 2011 for consented Thai individuals, aged 30-60 years. The screening program comprised blood testing, stool examination and serial ultrasonography every 6 months. RESULTS: During the first 3 years, 4,225 eligible individuals were enrolled. CCA was detected in 32 patients, with a mean age of 51.9 years (41-62 years), and 21/32 cases were at a curative resectable stage. The prevalence rate of CCA was 165.7 per 100,000 and one- and two-year incidence rate was 236.7/100,000 and 520.7/100,000, respectively. One- and 2-year overall survival rates of CCA patients were 90.9 and 61.5 %, respectively. Prognosis was better in resectable cases with 100 % 1-year and 77.8 % 2-year survival rates. Interestingly, premalignant pathological lesions (stage 0) were identified in 11 cases with 100 % 3-year survival rate. Serum biomarkers and alkaline phosphatase were not sufficient to detect early-stage disease. In 22 patients, stool samples were positive for Opistorchis viverrini, based on polymerase chain reaction. CONCLUSION: Detection of premalignant lesions and early-stage resectable CCA by ultrasonography resulted in improved clinical outcome. Ultrasonography should be offered as a first screening tool for CCA in an endemic area until other useful biological markers become available.

Real-World Data on the Diagnosis, Treatment, and Management of Hepatocellular Carcinoma in the Asia-Pacific: The INSIGHT Study.

Introduction: Hepatocellular carcinoma (HCC) is the sixth most commonly diagnosed cancer and the third leading cause of cancer death worldwide. While there has been rapid evolution in the treatment paradigm of HCC across the past decade, the extent to which these newly approved therapies are utilized in clinical practice in the real world is, however, unknown. The INSIGHT study was an investigator-initiated, multi-site longitudinal cohort study conducted to reflect real-world epidemiology and clinical practice in Asia-Pacific in the immediate 7-year period after the conclusion of the BRIDGE study. Methods: Data were collected both retrospectively (planned 30% of the total cohort size) and prospectively (planned 70%) from January 2013 to December 2019 from eligible patients newly diagnosed with HCC from 33 participating sites across 9 Asia-Pacific countries. Results: A total of 2,533 newly diagnosed HCC patients (1,052 in retrospective cohort and 1,481 in prospective cohort) were enrolled. The most common risk factor was hepatitis B in all countries except Japan, Australia, and New Zealand, where the prevalence of hepatitis C and diabetes were more common. The top three comorbidities reported in the INSIGHT study include cirrhosis, hypertension, and diabetes. We observe high heterogeneity in the first-line treatment recorded across countries and across disease stages, which significantly affects survival outcomes. Stratification by factors such as etiologies, tumor characteristics, the presence of extrahepatic metastases or macrovascular invasion, and the use of subsequent lines of treatment were performed. Conclusion: The INSIGHT study describes a wide spectrum of clinical management practices in HCC, where patient demographics, differential costs, and patient access to therapies may lead to wide geographical variations through the patient's treatment cycle, from diagnosis to clinical outcome. The high heterogeneity in patient outcomes demonstrates the need for more robust and clinical management strategies to be designed and adopted to bring about better patient outcomes.

A genomic enhancer signature associates with hepatocellular carcinoma prognosis.

Background & Aims: Lifestyle and environmental-related exposures are important risk factors for hepatocellular carcinoma (HCC), suggesting that epigenetic dysregulation significantly underpins HCC. We profiled 30 surgically resected tumours and the matched adjacent normal tissues to understand the aberrant epigenetic events associated with HCC. Methods: We identified tumour differential enhancers and the associated genes by analysing H3K27 acetylation (H3K27ac) chromatin immunoprecipitation sequencing (ChIP-seq) and Hi-C/HiChIP data from the resected tumour samples of 30 patients with early-stage HCC. This epigenome dataset was analysed with previously reported genome and transcriptome data of the overlapping group of patients from the same cohort. We performed patient-specific differential expression testing using multiregion sequencing data to identify genes that undergo both enhancer and gene expression changes. Based on the genes selected, we identified two patient groups and performed a recurrence-free survival analysis. Results: We observed large-scale changes in the enhancer distribution between HCC tumours and the adjacent normal samples. Many of the gain-in-tumour enhancers showed corresponding upregulation of the associated genes and vice versa, but much of the enhancer and gene expression changes were patient-specific. A subset of the upregulated genes was activated in a subgroup of patients' tumours. Recurrence-free survival analysis revealed that the patients with a more robust upregulation of those genes showed a worse prognosis. Conclusions: We report the genomic enhancer signature associated with differential prognosis in HCC. Findings that cohere with oncofoetal reprogramming in HCC were underpinned by genome-wide enhancer rewiring. Our results present the epigenetic changes in HCC that offer the rational selection of epigenetic-driven gene targets for therapeutic intervention or disease prognostication in HCC. Impact and Implications: Lifestyle and environmental-related exposures are the important risk factors of hepatocellular carcinoma (HCC), suggesting that tumour-associated epigenetic dysregulations may significantly underpin HCC. We profiled tumour tissues and their matched normal from 30 patients with early-stage HCC to study the dysregulated epigenetic changes associated with HCC. By also analysing the patients' RNA-seq and clinical data, we found the signature genes - with epigenetic and transcriptomic dysregulation - associated with worse prognosis. Our findings suggest that systemic approaches are needed to consider the surrounding cellular environmental and epigenetic changes in HCC tumours.

Corrigendum: Combining the SMAC mimetic LCL161 with Gemcitabine plus Cisplatin therapy inhibits and prevents the emergence of multidrug resistance in cholangiocarcinoma.

[This corrects the article DOI: 10.3389/fonc.2022.1021632.].

Combining the SMAC mimetic LCL161 with Gemcitabine plus Cisplatin therapy inhibits and prevents the emergence of multidrug resistance in cholangiocarcinoma.

Cholangiocarcinoma (CCA) is a highly lethal gastrointestinal malignancy that has one of the worst prognoses among solid tumors. The combination of Gemcitabine + Cisplatin (GEM/CIS) remains the standard first-line treatment for advanced stage CCA. However, this drug combination yields only a modest objective response rate, and in cases that initially respond to this treatment, drug resistance commonly rapidly develops. To improve the efficiency of GEM/CIS therapy for CCA, a thorough understanding of the mechanism of GEM/CIS resistance in CCA is required. To that end - in this study, we developed several acquired GEM/CIS-resistant CCA cell lines and we screened those cell lines for acquired vulnerability. The screening process revealed that subset of CCA with GEM/CIS resistance acquired vulnerability to the small-molecule second mitochondrial-derived activator of caspases (SMAC) mimetics LCL161 and Birinapant. The observed acquired vulnerability was found to be associated with upregulation of an inhibitor of apoptosis protein 2 (cIAP2), a known target of SMAC mimetics. LCL161 or cIAP2-shRNA downregulated cIAP2 and restored the sensitivity to GEM/CIS in GEM/CIS-resistant CCA cell lines and in in vivo GEM/CIS-resistant xenograft models. A strong synergic effect was observed when LCL161 was added to GEM/CIS. Interestingly, this synergism was also observed in drug-naïve CCA cell lines, xenografts, and patient-derived organoids. This triplet therapy also prevented the emergence of multidrug-resistant CCA in in vitro and in vivo models. Our findings suggest that activation of cIAP2 allows CCA to escape GEM/CIS, and that suppression of cIAP2 reestablishes the apoptotic profile of CCA, thus restoring its vulnerability to GEM/CIS. The results of this study indicate that combining the SMAC mimetic LCL161 with GEM/CIS inhibits and prevents the emergence of multidrug resistance in CCA.

The Acquired Vulnerability Caused by CDK4/6 Inhibition Promotes Drug Synergism Between Oxaliplatin and Palbociclib in Cholangiocarcinoma.

Cholangiocarcinoma (CCA) is one of the most difficult to treat cancers, and its nature of being largely refractory to most, if not all, current treatments results in generally poor prognosis and high mortality. Efficacious alternative therapies that can be used ubiquitously are urgently needed. Using acquired vulnerability screening, we observed that CCA cells that reprofile and proliferate under CDK4/6 inhibition became vulnerable to ribosomal biogenesis stress and hypersensitive to the anti-ribosome chemotherapy oxaliplatin. CCA cells overexpress the oncogenic ribosomal protein RPL29 under CDK4/6 inhibition in a manner that correlated with CDK4/6 inhibitor resistance. Depletion of RPL29 by small interfering RNAs (siRNAs) restored the sensitivity of CCA cells to CDK4/6 inhibition. Oxaliplatin treatment suppressed the RPL29 expression in the CDK4/6 inhibitor treated CCA cells and triggered RPL5/11-MDM2-dependent p53 activation and cancer apoptosis. In addition, we found that combination treatment with oxaliplatin and the CDK4/6 inhibitor palbociclib synergistically inhibited both parental and CDK4/6 inhibitor-resistant CCA, and prevented the emergence of CDK4/6 and oxaliplatin-resistant CCA. This drug combination also exerted suppressive and apoptosis effects on CCA in the in vitro 3-dimensional culture, patient-derived organoid, and in vivo xenograft CCA models. These results suggest the combination of the CDK4/6 inhibitor palbociclib and the anti-ribosome drug oxaliplatin as a potentially promising treatment for cholangiocarcinoma.

A snapshot of the 2020 conception of anatomic liver resections and their applicability on minimally invasive liver surgery. A preparatory survey for the Expert Consensus Meeting on Precision Anatomy for Minimally Invasive HBP Surgery.

BACKGROUND: The main aim of this survey was to analyze how liver surgeons perform liver resections and to define their conception of anatomic procedures within the incorporation of minimally invasive liver surgery (MILS). METHODS: The survey was distributed among liver surgeons. It mainly focused on personal experience on open and MILS, methods and landmarks, and experience on anatomic resections and Glissonean approach. RESULTS: A total of 445 valid answers from 54 countries was obtained. Surgeons performing MILS mainly have below 10 years of experience (81.8% of responders) and one third has never done complex MILS. New techniques, including indocyanine green demarcation are marginally used (<25%). More than 60% of surgeons do not make a full exposure of hepatic veins during MILS, mainly due to the risk of injury or not considering it to be of utility. Although 88% of responders agreed with the concept of anatomic resection as the "resection along the border/watersheds of each order division identified by the portal vein flow", only 55% of surgeons have ever performed MILS Glissonean approaches. CONCLUSIONS: Liver anatomy is not a static concept. Anatomic resections need training and precision. Standardization of complex anatomic resections by a minimally invasive approach should be encouraged.

Minimally invasive anatomic liver resection: Results of a survey of world experts.

BACKGROUND: Although the number of minimally invasive liver resections (MILRs) has been steadily increasing in many institutions, minimally invasive anatomic liver resection (MIALR) remains a complicated procedure that has not been standardized. We present the results of a survey among expert liver surgeons as a benchmark for standardizing MIALR. METHOD: We administered this survey to 34 expert liver surgeons who routinely perform MIALR. The survey contained questions on personal experience with liver resection, inflow/outflow control methods, and identification techniques of intersegmental/sectional planes (IPs). RESULTS: All 34 participants completed the survey; 24 experts (70%) had more than 11 years of experience with MILR, and over 80% of experts had performed over 100 open resections and MILRs each. Regarding the methods used for laparoscopic or robotic anatomic resection, the Glissonean approach (GA) was a more frequent procedure than the hilar approach (HA). Although hepatic veins were considered essential landmarks, the exposure methods varied. The top three techniques that the experts recommended for identifying IPs were creating a demarcation line, indocyanine green negative staining method, and intraoperative ultrasound. CONCLUSION: Minimally invasive anatomic liver resection remains a challenging procedure; however, a certain degree of consensus exists among expert liver surgeons.

The Tokyo 2020 terminology of liver anatomy and resections: Updates of the Brisbane 2000 system.

BACKGROUND: The Brisbane 2000 Terminology for Liver Anatomy and Resections, based on Couinaud's segments, did not address how to identify segmental borders and anatomic territories of less than one segment. Smaller anatomic resections including segmentectomies and subsegmentectomies, have not been well defined. The advent of minimally invasive liver resection has enhanced the possibilities of more precise resection due to a magnified view and reduced bleeding, and minimally invasive anatomic liver resection (MIALR) is becoming popular gradually. Therefore, there is a need for updating the Brisbane 2000 system, including anatomic segmentectomy or less. An online "Expert Consensus Meeting: Precision Anatomy for Minimally Invasive HBP Surgery (PAM-HBP Surgery Consensus)" was hosted on February 23, 2021. METHODS: The Steering Committee invited 34 international experts from around the world. The Expert Committee (EC) selected 12 questions and two future research topics in the terminology session. The EC created seven tentative definitions and five recommendations based on the experts' opinions and the literature review performed by the Research Committee. Two Delphi Rounds finalized those definitions and recommendations. RESULTS: This paper presents seven definitions and five recommendations regarding anatomic segmentectomy or less. In addition, two future research topics are discussed. CONCLUSIONS: The PAM-HBP Surgery Consensus has presented the Tokyo 2020 Terminology for Liver Anatomy and Resections. The terminology has added definitions of liver anatomy and resections that were not defined in the Brisbane 2000 system.

Pan-cancer pervasive upregulation of 3' UTR splicing drives tumourigenesis.

Most mammalian genes generate messenger RNAs with variable untranslated regions (UTRs) that are important post-transcriptional regulators. In cancer, shortening at 3' UTR ends via alternative polyadenylation can activate oncogenes. However, internal 3' UTR splicing remains poorly understood as splicing studies have traditionally focused on protein-coding alterations. Here we systematically map the pan-cancer landscape of 3' UTR splicing and present this in SpUR ( http://www.cbrc.kaust.edu.sa/spur/home/ ). 3' UTR splicing is widespread, upregulated in cancers, correlated with poor prognosis and more prevalent in oncogenes. We show that antisense oligonucleotide-mediated inhibition of 3' UTR splicing efficiently reduces oncogene expression and impedes tumour progression. Notably, CTNNB1 3' UTR splicing is the most consistently dysregulated event across cancers. We validate its upregulation in hepatocellular carcinoma and colon adenocarcinoma, and show that the spliced 3' UTR variant is the predominant contributor to its oncogenic functions. Overall, our study highlights the importance of 3' UTR splicing in cancer and may launch new avenues for RNA-based anti-cancer therapeutics.

Dynamic phenotypic heterogeneity and the evolution of multiple RNA subtypes in hepatocellular carcinoma: the PLANET study.

Intra-tumor heterogeneity (ITH) is a key challenge in cancer treatment, but previous studies have focused mainly on the genomic alterations without exploring phenotypic (transcriptomic and immune) heterogeneity. Using one of the largest prospective surgical cohorts for hepatocellular carcinoma (HCC) with multi-region sampling, we sequenced whole genomes and paired transcriptomes from 67 HCC patients (331 samples). We found that while genomic ITH was rather constant across stages, phenotypic ITH had a very different trajectory and quickly diversified in stage II patients. Most strikingly, 30% of patients were found to contain more than one transcriptomic subtype within a single tumor. Such phenotypic ITH was found to be much more informative in predicting patient survival than genomic ITH and explains the poor efficacy of single-target systemic therapies in HCC. Taken together, we not only revealed an unprecedentedly dynamic landscape of phenotypic heterogeneity in HCC, but also highlighted the importance of studying phenotypic evolution across cancer types.

Expert Consensus Guidelines: How to safely perform minimally invasive anatomic liver resection.

BACKGROUND: The concept of minimally invasive anatomic liver resection (MIALR) is gaining popularity. However, specific technical skills need to be acquired to safely perform MIALR. The "Expert Consensus Meeting: Precision Anatomy for Minimally Invasive HBP Surgery (PAM-HBP Surgery Consensus)" was developed as a special program during the 32nd meeting of the Japanese Society of Hepato-Biliary-Pancreatic Surgery (JSHBPS). METHODS: Thirty-four international experts gathered online for the consensus. A Research Committee performed a comprehensive literature review, classifying studies according to the Scottish Intercollegiate Guidelines Network method. Based on the literature review and experts' opinions, tentative recommendations were drafted and circulated among experts using online Delphi Rounds. Finally, formulated recommendations were presented online in the Expert Consensus Meeting of the JSHBPS on February 23rd, 2021. The final recommendations were validated and finalized by the 2nd Delphi Round in May 2021. RESULTS: Seven clinical questions were selected, and 22 recommendations were formulated. All recommendations reached more than 85% consensus among experts at the final Delphi Round. CONCLUSIONS: The Expert Consensus Meeting for safely performing MIALR has presented a set of clinical guidelines based on available literature and experts' opinions. We expect these guidelines to have a favorable effect on the safe implementation and development of MIALR.

Impact of COVID-19 on Hepatocellular Carcinoma Management: A Multicountry and Region Study.

PURPOSE: The COVID-19 pandemic has altered healthcare priorities which may adversely impact cancer management. We aimed to evaluate the impact of the pandemic on the diagnosis, treatment, and consultation methods for patients with hepatocellular carcinoma (HCC). PATIENTS AND METHODS: We conducted a survey among 27 hospitals from 14 Asia-Pacific countries, collecting hospital-level information on the number of newly diagnosed HCC cases during a pre-pandemic period (February to May 2019) and for the same period during the pandemic (February to May 2020). Information was also collected on delays in diagnosis and treatment, changes in treatment modalities and complication rates, changes in patient enrollment in clinical trials, and modes of patient consultation. The information was stratified by the Barcelona Clinic Liver Cancer (BCLC) stage. RESULTS: The survey included cohorts of 2789 and 2045 patients newly diagnosed with HCC during the pre- and pandemic period, respectively. A decline of 26.7% in new HCC cases was reported during the pandemic compared to the pre-pandemic. A sizable proportion of institutions reported delays in diagnosis (48.2% in BCLC 0/A/B and 51.9% in BCLC C), delays in treatment (66.7% in BCLC 0/A/B and 63.0% in BCLC C), changes in treatment modality (33.3% in BCLC 0/A/B and 18.5% in BCLC C), an increase in treatment complications (about 15% across all BCLC stages), and no growth in clinical trial enrollments during the pandemic. Furthermore, there was a decline of 27.3% in face-to-face patient consultations and an increase of 18.3% in video/telephonic consultations during the pandemic. A considerable variation in changes in HCC management was observed among countries. CONCLUSION: The COVID-19 pandemic has significantly impacted the management of HCC among Asia-Pacific countries. The impact varies according to the disease stage and country. Well thought-through long-term strategies are required to ameliorate the negative impact of the pandemic on HCC patients.

Useful maneuvers for precise laparoscopic liver resection.

Laparoscopic liver resection has evolved over the past decade and nearly replaced open exploration. This procedure not only provides comparable oncological outcomes, but it also has improved recovery after surgery. Many of the challenges presented by limitations of instruments and techniques have been overcome through adaptations and new developments, and it is possible that the remaining obstacles will be overcome within a few years. Moreover, as surgeons continue to gain experience, their technical knowledge has supported further improvement in minimally invasive approaches. This review examines every important procedures in performing a precise laparoscopic liver resection.

Risk factors associated with major intraoperative blood loss in hepatic resection for hepatobiliary tumor.

BACKGROUND AND PURPOSE: Hepatic resection is the mainstay treatment of hepatobiliary tumor Nowadays, mortality is less than 6%. However, morbidity is still high. Bleeding is one of the most common problems during hepatic resection which can sometimes lead to catastrophe. The purpose of the present study was to investigate the risk factors associated with major blood loss during hepatic resection for hepatobiliary tumor. MATERIAL AND METHOD: A total of 69 consecutive patients who underwent elective hepatic resection for hepatobiliary tumor from May 2002 to April 2004 were enrolled into this retrospective study. The Patients were divided into 2 groups(group I and II) according to the intraoperative blood loss. Patients who had a blood loss of more than 1000 ml were defined as the major blood loss group(group I). Thirteen variable factors were analyzed to determine the risk of major intraoperative blood loss. Operative outcomes between the two groups were also compared. RESULTS: Of the sixty-nine patients, 36 patients were in group I and 33 patients were in group II. 75% of the patients in group I and 36.4% of the patients in group II were transfused. Median blood transfusion in group I and II were 3 and 0 units of packed red cell. Univariate analysis showed tumor size, extent of hepatic resection, tumor pathology and operative time were factors affecting major intraoperative blood loss. However, multivariate analysis showed only operative time and tumor size to be independent risk factors. Patients in group I had higher surgical morbidity and prolonged hospital stay compared with patients in group II. CONCLUSION: Blood loss is still a major concern in performing hepatic resection. From the present study, tumor size and operative time are the independent factors affecting major intraoperative blood loss. Proper screening or a surveillance program may enhance the chance to find small tumors. Refined operative techniques such as anterior approach and liver hanging would facilitate resection for large right sided tumors.

(11)C-Choline and FDG PET/CT Imaging of Primary Cholangiocarcinoma: A Comparative Analysis.

OBJECTIVES: This study aimed to compare the diagnostic values of (11)C-choline and (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography/computed tomography (PET/CT) in patients with cholangiocarcinoma (CCA). METHODS: This prospective study was conducted on 10 patients (6 males and 4 females), aged 42-69 years, suspected of having CCA based on CT or magnetic resonance imaging (MRI) results. (11)C-choline and (18)F-FDG PET/CT studies were performed in all patients over 1 week. PET/CT results were visually analyzed by 2 independent nuclear medicine physicians and quantitatively by calculating the tumor-to-background ratio (T/B). RESULTS: No (11)C-choline PET/CT uptake was observed in primary extrahepatic or intrahepatic CCA cases. Intense (18)F-FDG avidity was detected in the tumors of 8 patients (%80). Two patients, who were (18)F-FDG negative, had primary extrahepatic CCA. Ki-67 measurements were positive in all patients (range; 14.2%-39.9%). The average T/B values of (11)C-choline and (18)F-FDG were 0.4±0.2 and 2.0±1.0 in all cases of primary CCA, respectively; these values were significantly lower for (11)C-choline (P<0.005). Both FDG and (11)C-choline PET/CT detected metastatic CCA foci in all 8 patients (two patients had no metastases). CONCLUSION: As the results suggested, primary CCA lesions showed a poor avidity for (11)C-choline, whereas (18)F-FDG PET/CT was of value for the detection of most primary CCA cases. In contrast to primary lesions, metastatic CCA lesions showed (11)C-choline avidity.