K-ras mutation analysis of residual liquid-based cytology specimens from endoscopic ultrasound-guided fine needle aspiration improves cell block diagnosis of pancreatic ductal adenocarcinoma

Advances in diagnostic liquid-based cytology

Liquid-based cytology (LBC) has changed the landscape of gynaecological cytology. A growing demand exists for LBC in diagnostic cytology, particularly for ancillary testing, such as immunocytochemistry and molecular testing. Ancillary testing solely based on conventional preparation (CP) methods remains challenging. Recently, the increased demand for specialist testing and minimally invasive techniques, such as endoscopic ultrasonography fine-needle aspiration, to obtain cellular samples has led to an increasing demand for ancillary testing on cytology LBC supernatant, slides and cell block (CB). This facilitates the diagnosis and prognosis in cytology samples enabling personalized treatment. An understanding of the history and future prospects of LBC is crucial for its application in routine diagnostics by cytopathologists and cytotechnologists. In this review, we initiated an internet search using the keyword 'liquid-based cytology', and we conducted a literature review to discuss the usefulness of combined diagnosis of LBC and CP, immunocytochemistry and molecular testing and assessed the quality of nucleic acids in diagnostic LBC. High-quality and cell-rich diagnostic LBC surpassed the CP method alone in terms of reliability and versatility of ancillary testing in cytological diagnosis. Conclusively, diagnostic LBC lends itself to various new technologies and is expected to continue evolving with innovations in the future.

Tissue processing of endoscopic ultrasound-guided fine-needle aspiration specimens from solid pancreatic lesions

Now that tissue cores can be obtained using fine-needle biopsy (FNB) needles, the ways tissues are handled for endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) are changing. Direct smear, touch smear of core tissues, and centrifugation have been used for cytological examinations, and liquid-based cytology (LBC), which allows immunostaining and genetic tests that use residual samples, is emerging as an alternative. We emphasize that liquid cytology (Cytospin™ cytology and LBC) is still important, because it enables the diagnosis of pancreatic ductal adenocarcinoma (PDAC) when cancerous cells are scarce in specimens. Cell blocks are being replaced by core tissues obtained via FNB needles. Recent reports indicate that rapid on-site evaluation (ROSE) is not necessary when FNB needles are used, and macroscopic on-site evaluation is used to evaluate specimen adequacy. Macroscopic findings of specimens are helpful in the diagnostic workup and for clarifying specimen-handling methods. In addition to the red strings and white cores observed in PDAC, mixed red and white strings, gray tissues, and gelatinous tissues are observed. Gray (necrotic) tissues and gelatinous (mucus) tissues are more suitable than histology for cell block or cytological processing. Tumor cells in neuroendocrine tumors (NETs) are numerous in red strings but cannot be observed macroscopically. ROSE might thus be necessary for lesions that may be NETs. Core tissues can be used for genetic tests, such as those used for KRAS mutations and comprehensive genomic profiling. Cytological materials, including slides and LBC specimens, can also be genetic test materials.

K-ras gene mutation analysis to diagnosis pancreatic adenocarcinoma from endoscopic ultrasound-guided tissue acquisition; a systematic review and meta-analysis

BACKGROUND

Endoscopic ultrasound-guided tissue acquisition (EUS-TA) has high sensitivity for the pathological diagnosis of pancreatic masses, but also a high false-negative rate. K-ras gene mutations occur in over 75 % of pancreatic ductal adenocarcinomas (PDAC), and this meta-analysis evaluated the utility of detecting K-ras gene mutations from EUS-TA specimens for the diagnosis of PDAC.

METHODS

Relevant studies in PubMed, the Cochrane Library, and Web of Science were systematically searched. Meta-analysis was performed on data from the selected studies using a bivariate model to provide pooled values of sensitivity, specificity, and their 95 % confidence intervals (CIs).

RESULTS

This meta-analysis included 1521 patients (from 10 eligible studies) who underwent EUS-TA with K-ras gene mutation analysis for diagnosis of pancreatic solid masses. The pooled estimates of sensitivity and specificity were 76.6 % (95 % CI, 70.9-81.5 %) and 97.0 % (95 % CI, 94.0-98.5 %), respectively, for pathological diagnosis, 75.9 % (95 % CI 69.5-81.4 %) and 95.3 % (95 % CI, 92.3-97.2 %) for K-ras gene mutation analysis, and 88.7 % (95 % CI 87.1-91.7 %) and 94.9 % (95 % CI, 91.5-97.0 %) for pathological diagnosis in combination with K-ras gene mutation analysis. The sensitivity for diagnosis of PDAC was significantly higher for pathological diagnosis in combination with K-ras gene mutation analysis than for pathological diagnosis or K-ras gene mutation analysis alone (both, p < 0.001). There was no difference in specificity between pathological diagnosis in combination with K-ras gene mutation analysis and both either (p = 0.234, 0.945, respectively).

CONCLUSIONS

K-ras gene mutation analysis in combination with to pathological diagnosis of EUS-TA increases the accuracy of differential diagnosis of PDAC.

Echoendoscopic ultrasound pancreatic adenocarcinoma diagnosis and theranostic approach: should KRAS mutation research be recommended in everyday practice?

Background

The impact of KRAS mutation testing on pancreatic ductal adenocarcinoma (PDAC) samples by endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) for reducing the need to repeat EUS-FNA has been demonstrated. Such testing however is not part of standard practice for endoscopic ultrasound-guided fine-needle biopsy (EUS-FNB).

Objectives

We aim to analyse the proportion of non-contributive samples by EUS-FNB and to evaluate the impact of KRAS mutation testing on the diagnosis, theranostics and survival.

Design

In this retrospective study, the impact on diagnosis and survival of KRAS testing for contributive and non-contributive samples by EUS-FNB was analysed.

Methods

The EUS-FNB samples, combined with KRAS testing using the Idylla® technique on liquid-based cytology from patients with PDAC between February 2019 and May 2023, were retrospectively reviewed. The cytology results were classified according to the guidelines of the World Health Organization System for Reporting Pancreaticobiliary Cytopathology (WHOSRPC).

Results

A total of 85 EUS-FNB specimens were reviewed. In all, 25 EUS-FNB samples did not lead to a formal diagnosis of PDAC according to the WHOSRPC (30.2%). Out of these 25, 11 (44%) could have been considered positive for a PDAC diagnosis thanks to the KRAS mutation test without carrying out further diagnosis procedures. The sensitivity of KRAS mutation testing using the Idylla technique was 98.6%. According to the available data, survival rates were not statistically different depending on the type of mutation.

Conclusion

KRAS mutation testing on liquid-based cytology using the Idylla or equivalent technique, combined with the PDAC EUS-FNB sample, should become a standard for diagnosis to avoid delaying treatment by doing another biopsy. Furthermore, knowledge of the KRAS status from treatment initiation could be used to isolate mutations requiring targeted treatments or inclusion in clinical research trials, especially for wild-type KRAS PDAC.

Endoscopic ultrasound-guided tissue acquisition for pancreatic ductal adenocarcinoma in the era of precision medicine

Endoscopic ultrasound-guided tissue acquisition (EUS-TA) currently plays a central role in the diagnosis of pancreatic ductal adenocarcinoma (PDAC). Although fine-needle aspiration has been the gold standard, novel biopsy needles for fine-needle biopsy (FNB) were developed to overcome its limitations, which include low tumor cellularity and the inability to retain cellular architecture. Following recent improvements in FNB needles, the pathological diagnosis has shifted from cytology to histology and now to genetic diagnosis. Genetic analysis using EUS-TA samples began with a search for the presence of K-ras mutations. However, the introduction of next-generation sequencers has dramatically changed genetic analysis and led to the gradual elucidation of the mechanism of PDAC, enabling personalized medicine by performing multiple gene analyses simultaneously. Comprehensive genomic profiling is currently applied in the clinical setting and there is an increasing need for gene analysis using EUS-TA samples. Although target genome sequencing is feasible even with cytological specimens, it can be difficult to proceed with full genetic analysis including whole-exome sequence or whole-genome sequence if the samples are too small. Genetic analysis will become highly important in determining indications for personalized medicine such as poly (ADP-ribose) polymerase inhibitors or immune checkpoint inhibitors. Therefore, the endosonographer must always take gene analysis into consideration when collecting samples for diagnosis and further improvement of the puncture technique and needle development are anticipated in the future.

The usefulness of liquid-based cytology for endoscopic ultrasound-guided tissue acquisition of solid pancreatic masses

Liquid-based cytology (LBC) is used primarily for cervical cytology, although it is also used for analyzing liquid samples such as urine and ascites specimens, as well as fine needle aspiration material, such as those obtained from breast and thyroid. The usefulness of the LBC method for endoscopic ultrasound-guided tissue acquisition (EUS-TA) of solid pancreatic masses was recently reported. The LBC method can produce multiple pathological slides and can be applied to immunocytochemistry and genetic analyses. In this article, we review the usefulness of LBC for EUS-TA of solid pancreatic masses.

Diagnostic Strategies for Urologic Cancer Using Expression Analysis of Various Oncogenic Surveillance Molecules—From Non-Coding Small RNAs to Cancer-Specific Proteins

Urinary-tract-related tumors are prone to simultaneous or heterogeneous multiple tumor development within the primary organ. Urologic tumors have a very high risk of recurrence in the long and short term. This may be related to the disruption of homeostasis on the genetic level, such as the induction of genetic mutations due to exposure to various carcinogenic factors and the disruption of cancer suppressor gene functions. It is essential to detect the cancer progression signals caused by genetic abnormalities and find treatment therapies. In this review, we discuss the usefulness of tumor-expressing clinical biomarkers for predicting cancer progression. Furthermore, we discuss various factors associated with disturbed intracellular signals and those targeted by microRNAs, which are representative of non-coding small RNAs.

The Utility of Endoscopic-Ultrasonography-Guided Tissue Acquisition for Solid Pancreatic Lesions

Endoscopic-ultrasonography-guided tissue acquisition (EUS-TA) has been widely performed for the definitive diagnosis of solid pancreatic lesions (SPLs). As the puncture needles, puncture techniques, and sample processing methods have improved, EUS-TA has shown higher diagnostic yields and safety. Recently, several therapeutic target genomic biomarkers have been clarified in pancreatic ductal carcinoma (PDAC). Although only a small proportion of patients with PDAC can benefit from precision medicine based on gene mutations at present, precision medicine will also be further developed for SPLs as more therapeutic target genomic biomarkers are identified. Advances in next-generation sequencing (NGS) techniques enable the examination of multiple genetic mutations in limited tissue samples. EUS-TA is also useful for NGS and will play a more important role in determining treatment strategies. In this review, we describe the utility of EUS-TA for SPLs.

Evaluation and diagnostic value of next-generation sequencing analysis of residual liquid-based cytology specimens of pancreatic masses

BACKGROUND

Liquid-based cytology (LBC) is a widely used method for processing specimens obtained by endoscopic biopsy. This study evaluated next-generation sequencing (NGS) analysis of LBC specimens to improve the diagnostic accuracy of pancreatic lesions.

METHODS

Upon the diagnosis of a suspected pancreatic mass, LBC residues were used retrospectively. The quantity and quality of DNA extracted from residual LBC samples were evaluated, and an NGS analysis targeting 6 genes (KRAS, GNAS, TP53, CDKN2A, SMAD4, and PIK3CA) was performed.

RESULTS

The library was prepared from LBC specimens taken from 52 cases: 44 were successful, and 8 preparations failed. An analysis of DNA quantity and quality suggested that the success or failure of NGS implementation depended on both properties. The final diagnosis was achieved by a combination of the pathological analysis of the surgical excision or biopsy material with clinical information. Among the 33 cases of pancreatic ductal adenocarcinoma (PDAC), KRAS, TP53, CDKN2A, and SMAD4 mutations were identified in 31 (94%), 16 (48%), 3 (9%), and 2 (6%), respectively. Among the 11 benign cases, only a KRAS mutation was identified in 1 case. On the basis of NGS results, 18 of 33 PDACs (55%) were classified as highly dysplastic or more, and 10 of 11 benign lesions were evaluated as nonmalignant, which was consistent with the final diagnosis.

CONCLUSIONS

NGS analysis using LBC specimens from which DNA of appropriate quantity and quality has been extracted could contribute to improving the assessment of pancreatic tumor malignancies and the application of molecular-targeted drugs.

Kras Gene Analysis Using Liquid-Based Cytology Specimens Predicts Therapeutic Responses and Prognosis in Patients with Pancreatic Cancer

Simple Summary

New therapeutic strategies are needed to improve the prognosis of pancreatic ductal adenocarcinoma (PDAC) and developing biomarkers that can guide individualized treatment decisions is an important part of these strategies. In this study, we found that unresectable PDAC patients harboring wild-type Kras had significantly longer progression-free survival (PFS) and overall survival (OS) than those harboring mutant Kras after undergoing first-line gemcitabine and nab-paclitaxel (GA) therapy and that wild-type Kras was a significant predictor of longer PFS and OS. This is the first report suggesting that Kras gene analysis has the potential to predict therapeutic responses to GA and the prognosis of unresectable PDAC.

Abstract

Background: Although several molecular analyses have shown that the Kras gene status is related to long-term survival of patients with pancreatic ductal adenocarcinoma (PDAC), the results remain controversial. Here, we examined the Kras gene status in a cohort of unresectable PDAC patients who underwent first-line therapy with gemcitabine and nab-paclitaxel (GA) and assessed differences in chemotherapy responses and survival. Methods: Patients with a histological diagnosis of PDAC (based on EUS-guided fine-needle aspiration) from 2017 to 2019 were enrolled. Tumor genomic DNA was extracted from residual liquid-based cytology specimens and Kras mutations were assessed using the quenching probe method. The relationships between the Kras status and progression-free survival (PFS) and overall survival (OS) were assessed. Results: Of the 110 patients analyzed, 15 had wild-type Kras. Those with the wild-type gene showed significantly longer PFS and OS than those with mutant Kras (6.9/5.3 months (p = 0.044) vs. 19.9/11.8 months (p = 0.037), respectively). Multivariate analyses identified wild-type Kras as a significant independent factor associated with longer PFS and OS (HR = 0.53 (p = 0.045) and HR = 0.35 (p = 0.007), respectively). Conclusions: The analysis of the Kras gene status could be used to predict therapeutic responses to GA and prognosis in unresectable PDAC patients.

Impact of LBC fixative type and fixation time on molecular analysis of pancreatic cancer cells: A comparative study of cell morphology, antigenicity and nucleic acids

Introduction:

Liquid-based cytology (LBC) has been widely used since 2000. Next-Generation Sequencing (NGS) analysis of residual specimens in LBC fixative may also be performed for pancreatic cancer in the near future. We examined cell morphology, antigenicity and nucleic acids in pancreatic cancer cells at different fixation times using two types of LBC fixatives.

Methods:

PANC-1 cells were fixed in 1 ml CytoRich Red (CR), CytoRich Blue (CB), 95% ethanol (95% AL) or 10% neutral buffered formalin (10% NBF) and evaluated for cell area, antigenicity and nucleic acids with fixation times of 1 hour and 1, 3, 9, and 14 days. Antigenicity was evaluated by immunocytochemical staining for p53 and CK20, and nucleic acid fragmentation was assessed by real-time PCR.

Results:

There was no difference in total cell area between 1 hour and 14 day fixation times for the CR group, but the CB group showed cell contraction with 9 days fixation. In immunocytochemical staining, the CR group showed high p53 and CK20 positivity even after 14 days fixation. The CB group had a lower p53 positive rate than the CR group from 1 hour fixation. For nucleic acid fragmentation, Ct values for the CR group increased with fixation time. The CB group had consistently low Ct values.

Conclusion:

Different LBC fixatives and fixation time can have varying effects on cell morphology, antigenicity and nucleic acids in pancreatic cancer cells. Therefore, fixative type and fixation time should be considered for molecular testing on residual samples in LBC fixatives.

Randomized controlled trial comparing a conventional needle and a novel needle for endoscopic ultrasound (EUS)-guided histology of peripancreatic masses

INTRODUCTION

Cytological study of samples obtained by Endoscopic ultrasound (EUS)-guided fine-needle aspiration (EUS-FNA) allows for recognition of clear signs of malignant transformation. However, certain neoplasms can be difficult to diagnose without histological analysis. Recently, a novel EUS-guided fine needle biopsy (EUS-FNB) needle was developed to increase tissue acquisition. This study set out to investigate the usefulness of this novel EUS-FNB needle (NEFN) in terms of obtaining a proper histology compared with a conventional EUS-FNA needle (CEFN).

METHODS

This investigation was a prospective, single-blind, randomized study in a single academic hospital. Primary outcome was the acquisition rate of an appropriate and sufficient specimen for histologic assessment. Secondary outcomes were diagnostic yield of peripancreatic masses using a CEFN and a NEFN. Furthermore, we assessed the feasibility of determining K-ras mutation status according to needle type.

RESULTS

The study enrolled 56 consecutive patients. Technical success rates were 96.6% (28/29) for the CEFN and 100% (27/27) for the NEFN (P = 1.000). No complications occurred during or after the procedure in either needle group. An adequate sample for cytologic diagnosis was obtained in 89.7% (26/29) of patients in the CEFN group vs 96.3% (26/27) of patients in the NEFN group (P = .612). For histologic diagnosis, a sample with a biopsy adequacy score of 2 or more was obtained in 41.4% (12/29) of CEFN-acquired samples vs 88.9% (24/27) of NEFN-acquired samples (P < .001). K-ras mutation analysis using histologic specimens was possible in 13 (44.8%) CEFN-acquired samples and 25 (92.6%) of NEFN-acquired samples. This difference was significant (P < .001).

CONCLUSIONS

The present study suggests that the NEFN is an effective and reliable alternative compared to a CEFN in terms of tissue acquisition rate and quality of histologic sampling.

Evaluation of Local Recurrence of Pancreatic Cancer by KRAS Mutation Analysis Using Washes from Endoscopic Ultrasound-Guided Fine-Needle Aspiration

BACKGROUND AND AIMS

The sensitivity of endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) for diagnosing the recurrence of pancreatic cancer is usually low because of difficulties in obtaining adequate samples for pathological examinations. We evaluated the efficacy of highly sensitive KRAS mutation analysis using EUS-FNA washes to detect cancer recurrence.

METHODS

Nineteen consecutive patients with suspected pancreatic cancer recurrence after surgical resection were enrolled. All underwent EUS-FNA, and samples were obtained for pathological examination. After the first session, the inside of the FNA needle was washed with saline for DNA extraction. KRAS mutations were examined using digital droplet PCR (dPCR).

RESULTS

The median needle puncture number used to obtain adequate pathological samples was two (range 1-6). In ten patients pathologically diagnosed with malignant pancreatic cancer, nine patients tested positive for a KRAS mutation. All patients who were not diagnosed with a malignant pancreatic cancer tested negative for a KRAS mutation. About half of surgically resected primary cancers (9/19) showed double KRAS mutations (G12V and G12D); however, all but one wash sample showed a single KRAS mutation, G12D. After including one patient who showed a malignant recurrence during follow-up, the sensitivities of a pathological diagnosis and KRAS analysis to detect recurrence were 90.9% and 81.8%, respectively.

CONCLUSIONS

KRAS mutation analysis of needle wash samples using dPCR is a new methodology for the diagnosis of the local recurrence of pancreatic cancer. The diagnostic ability of dPCR with a one-time needle wash sample was comparable to a pathological diagnosis with multiple samplings.

Small but powerful: the promising role of small specimens for biomarker testing

Emphasis on the use of small specimens for biomarker testing to provide prognostic and predictive information for guiding clinical management for patients with advanced-stage cancer has been increasing. These biomarker tests include molecular analysis, cytogenetic tests, and immunohistochemical assays. Owing to the limited nature of the cellular material procured in these small specimens, which are collected using minimally invasive techniques (ie, fine needle aspiration and core needle biopsy), pathologists have been required to triage these samples judiciously and provide the clinically relevant genomic information required for patient care. Awareness of the advantages and limitations of these specimen preparations and the specific preanalytic requirements for the testing methods will help pathologists to develop optimal strategies to maximize the chances of effectively using these samples for comprehensive diagnostic and relevant biomarker testing.

Role of oncogenic KRAS in the diagnosis, prognosis and treatment of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is predicted to be the second most common cause of death within the next 10 years. The prognosis for this disease is poor despite diagnostic progress and new chemotherapeutic regimens. The oncogenic KRAS mutation is the major event in pancreatic cancer; it confers permanent activation of the KRAS protein, which acts as a molecular switch to activate various intracellular signalling pathways and transcription factors inducing cell proliferation, migration, transformation and survival. Several laboratory methods have been developed to detect KRAS mutations in biological samples, including digital droplet PCR (which displays high sensitivity). Clinical studies have revealed that a KRAS mutation assay in fine-needle aspiration material combined with cytopathology increases the sensitivity, accuracy and negative predictive value of cytopathology for a positive diagnosis of pancreatic cancer. In addition, the presence of KRAS mutations in serum and plasma (liquid biopsies) correlates with a worse prognosis. The presence of mutated KRAS can also have therapeutic implications, whether at the gene level per se, during its post-translational maturation, interaction with nucleotides and after activation of the various oncogenic signals. Further pharmacokinetic and toxicological studies on new molecules are required, especially small synthetic molecules, before they can be used in the therapeutic arsenal for pancreatic ductal adenocarcinoma.

Usefulness of rapid on-site evaluation specimens from endoscopic ultrasound-guided fine-needle aspiration for cancer gene panel testing: A retrospective study

Pancreatic cancer (PC) is a highly lethal malignancy, with a 5-year survival rate of 6%. Cancer gene panel testing is expected to allow selection of suitable therapeutic drugs in individual patients with PC and improve their prognosis. Although somatic mutations can be identified in formalin-fixed, paraffin-embedded samples derived from surgical specimen, the rate of surgical indication among patients with PC is only 20%. To acquire genome information with a less invasive method, we used rapid on-site evaluation (ROSE) specimens from endoscopic ultrasound-guided fine-needle aspiration. The present study aimed to retrospectively evaluate the utility of comprehensive cancer gene panel testing with ROSE specimens. DNA was extracted from preserved ROSE specimens of 26 patients diagnosed with PC between 2011 and 2017. DNA sequences of oncogenes and cancer-related genes were determined using the Ion AmpliSeq Comprehensive Caner Panel. We compared KRAS mutations between cancer gene panel testing by next-generation sequencing (NGS) and KRAS mutation analysis by polymerase chain reaction. The mean yield of DNA per extraction from ROSE specimens was 171 ng (range, 34-478 ng). On cancer gene panel testing, we noted KRAS mutations (92%), TP53 mutations (50%), CDKN2A mutations (15%), and SMAD4 mutations (31%). The concordance rate of KRAS mutations between cancer gene panel testing by NGS using ROSE specimens and KRAS mutation analysis by the companion diagnostics using residual materials was 81%. Among five cases of KRAS discordance, three showed KRAS mutations in cancer gene panel testing but not in KRAS mutation analysis. Cancer gene panel testing with ROSE specimens can help stratify unresectable PC patients without additional invasive approaches, and it can be used for therapeutic drug selection.

DNA sequencing of cytopathologically inconclusive EUS-FNA from solid pancreatic lesions suspicious for malignancy confirms EUS diagnosis

Background and Objectives:

EUS-FNA is inconclusive in up to 10%–15% of patients with solid pancreatic lesions (SPLs). We aimed to investigate whether supplementary genetic analyses with whole-exome sequencing add diagnostic value in patients with SPLs suspicious of malignancy but inconclusive EUS-FNA.

Patients and Methods:

Thirty-nine patients, who underwent EUS-FNA of an SPL were retrospectively included. Three groups were defined: 16 (41.0%) had suspected malignancy on EUS confirmed by cytology (malignant), 13 (33.3%) had suspected malignancy on EUS but benign cytology (inconclusive), and 10 (25.6%) had benign EUS imaging and cytology (benign). Areas with the highest epithelial cell concentrations were macro-dissected from the FNA smears from each patient, and extracted DNA was used for whole-exome sequencing by next-generation sequencing of a selected gene panel including 19 genes commonly mutated in cancer.

Results:

Pathogenic mutations in K-RAS,TP53, and PIK3CA differed significantly between the three groups (P < 0.001, P = 0.018, and P = 0.026, respectively). Pathogenic mutations in KRAS and TP53 were predominant in the inconclusive (54% and 31%, respectively) and malignant groups (81.3% and 50%, respectively) compared to the benign group (0%). Malignant and inconclusive diagnoses correlated strongly with poor overall survival (P < 0.001).

Conclusion:

Whole-exome sequencing of genes commonly mutated in pancreatic cancer may be an important adjunct in patients with SPLs suspicious for malignancy on EUS but with uncertain cytological diagnosis.

Liquid Biopsy Approach for Pancreatic Ductal Adenocarcinoma

Pancreatic cancer is a public health problem because of its increasing incidence, the absence of early diagnostic tools, and its aggressiveness. Despite recent progress in chemotherapy, the 5-year survival rate remains below 5%. Liquid biopsies are of particular interest from a clinical point of view because they are non-invasive biomarkers released by primary tumours and metastases, remotely reflecting disease burden. Pilot studies have been conducted in pancreatic cancer patients evaluating the detection of circulating tumour cells, cell-free circulating tumour DNA, exosomes, and tumour-educated platelets. There is heterogeneity between the methods used to isolate circulating tumour elements as well as the targets used for their identification. Performances for the diagnosis of pancreatic cancer vary depending of the technique but also the stage of the disease: 30–50% of resectable tumours are positive and 50–100% are positive in locally advanced and/or metastatic cases. A significant prognostic value is demonstrated in 50–70% of clinical studies, irrespective of the type of liquid biopsy. Large prospective studies of homogeneous cohorts of patients are lacking. One way to improve diagnostic and prognostic performances would be to use a combined technological approach for the detection of circulating tumour cells, exosomes, and DNA.

Comprehensive validation of liquid-based cytology specimens for next-generation sequencing in cancer genome analysis

In addition to conventional cytology, liquid-based cytology (LBC) is also used for immunocytochemistry and gene analysis. However, an appropriate method to obtain high quality DNA for next-generation sequencing (NGS) using LBC specimens remains controversial. We determined the optimal conditions for fixation with an alcohol-based fixative for LBC and DNA extraction using cultured cancer cell lines and clinical specimens. The extracted DNA was processed for NGS after the DNA quality was confirmed based on the DNA concentration and degree of degradation. The optimal conditions for cultured cells to obtain high quality DNA were to fix the cells at a density of 6 × 10³ or 2 × 10⁴ cells/mL and to use the magnetic bead-based DNA extraction method. Even after storing the fixed cells for 90 days, DNA extracted using the above and other extraction kits, including membrane-based methods, did not undergo degradation. Furthermore, 5-year-old residual LBC samples demonstrated high DNA quality that was suitable for NGS. Furthermore, a cancer genome panel analysis was successfully performed with DNA extracted from cultured cells fixed at 6 × 10³ cells/mL for 90 days, and with DNA from residual LBC samples even after 1 year of storage. Residual LBC samples may be a useful source of DNA for clinical NGS to promote genome-based cancer medicine.

Diagnostic Efficacy of Liquid-Based Cytology in Endoscopic Ultrasound-Guided Fine Needle Aspiration for Pancreatic Mass Lesions During the Learning Curve: A Retrospective Study

OBJECTIVES

The diagnostic yield of endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) cytology widely varies depending on the treatment method used. Liquid-based cytology (LBC) has gained popularity in the gynecological field because of its efficacy in collection of target cells and simplicity in the manipulation of specimens. Since the introduction of EUS-FNA at our institution, we have used LBC for the diagnosis of pancreatic mass lesions. This study aims to investigate the diagnostic efficacy of EUS-FNA with LBC in patients with pancreatic mass lesions during the learning curve for EUS-FNA.

METHODS

In this study, we retrospectively enrolled 222 patients with pancreatic mass lesions who were diagnosed using EUS-FNA with LBC between 2011 and 2016. The diagnostic yields for EUS-FNA with LBC for pancreatic mass lesions were evaluated.

RESULTS

The diagnostic sensitivity, specificity, and accuracy for malignancy were found to be 93.9%, 95.1%, and 94.1%, respectively.

CONCLUSIONS

This study suggests that EUS-FNA with LBC for specimens provides good diagnostic efficacy in patients with pancreatic mass lesions even during the learning curve for EUS-FNA.

Analyses on K-ras mutations and fascin expression in patients with cardia cancer

Mutations of K-rat sarcoma (K-ras) in patients with cardia cancer and their effects on the expression of fascin were investigated. A total of 90 cardia cancer patients treated in Jining First People's Hospital from March 2014 to March 2017 were randomly selected. Genomic deoxyribonucleic acid (DNA) was extracted from paraffin-embedded cardia cancer specimens. Pyrosequencing was applied to detect sequences of K-ras gene in all patients and to analyze the mutations of K-ras gene. Then, genotyping of mutations at each mutation site was carried out using quantitative polymerase chain reaction (qPCR). The expression level of fascin in patients was measured via immunohistochemistry and qPCR. The results revealed that among 90 patients with cardia cancer, 21 patients had K-ras mutations (23.3%), including 20 cases of exon 12 mutation and 1 case of exon 13 mutation. Risk factor analyses revealed that alcohol abuse was a high risk factor for mutations (p<0.05). There was no significant difference in the mutation probability between heterozygotes and homozygotes for four mutations at codon 12 (p>0.05). The heterozygote at codon 13 had a higher mutation probability than homozygote (p<0.05). Immunohistochemistry suggested that the number of positive cells in the mutant group was larger than that in the non-mutant group (p<0.05). The results of qPCR showed that the expression level of fascin gene in the mutant group was 2.3 times higher than that in the non-mutant group (p<0.05). In conclusion, the probability of codon 12 mutation in K-ras gene is increased in patients with cardia cancer, and fascin is highly expressed in mutant patients, which is positively correlated with the mutations in K-ras gene.

Abnormal immunolabelling of SMAD4 in cell block specimens to distinguish malignant and benign pancreatic cells

BACKGROUND

Accurate diagnosis of malignant and benign pancreatic lesions can be challenging, especially with endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) samples that are small and/or degraded. In the present study, we determined how to best evaluate abnormal SMAD4 expression by immunohistochemical staining on cell block specimens from EUS-FNA samples.

RESULTS

In surgically resected pancreas, when abnormal SMAD4 immunolabelling was evaluated as negative SMAD4 expression, the sensitivity was low (33%), but when it was evaluated as decreased SMAD4 expression, the sensitivity improved (53%). Specificity and positive predictive value were high for both evaluations. There were no false-positive cases. In cell block specimens, decreased SMAD4 expression showed 47% sensitivity and 72% specificity, while negative SMAD4 expression showed lower sensitivity (20%) and higher specificity (100%). Both evaluations in cell block specimens showed lower sensitivity and specificity compared to resected specimens. False-positive and -negative rates were higher for cell blocks than for resected specimens.

CONCLUSIONS

Decreased SMAD4 immunolabelling provided improved sensitivity as compared to negative SMAD4 immunolabelling; therefore, it is important to compare SMAD4 expression in a sample to its expression in normal cells. Abnormal SMAD4 labelling showed low sensitivity and high specificity; therefore, SMAD4 staining using EUS-FNA samples might be helpful to detect malignancies that possess SMAD4 gene abnormalities.