The Japanese Society of Pathology Practical Guidelines on the handling of pathological tissue samples for cancer genomic medicine

Effect of storage temperature on nucleic acid quality in formalin-fixed paraffin-embedded tissue samples

Formalin-fixed paraffin-embedded (FFPE) tissue samples are widely used for genomic analyses in clinical and research settings. However, prolonged storage at room temperature may compromise nucleic acid quality, potentially affecting the reliability of molecular testing. In this study, we investigated the impact of various storage temperatures and repeated temperature changes on nucleic acid quality in FFPE samples. Four surgically resected tumor cases were analyzed. Following cold ischemia times of 29-60 min, tumor tissues were sampled upon arrival at the pathology department, divided into five equal parts, and fixed in 10 % neutral buffered formalin. The resulting FFPE blocks were stored at 18 °C, 4 °C, -20 °C, -80 °C, or - 150 °C. After storage, the blocks were returned to room temperature for sectioning and analysis. DNA and RNA quality were assessed at 3, 6, and 12 months using DNA integrity number (DIN), short-to-long cycle threshold (S/L Ct) ratio, RNA integrity number (RIN), and DV200. Samples stored at 18 °C and 4 °C exhibited time-dependent deterioration in certain indicators, whereas those stored at -20 °C or below maintained stable nucleic acid quality. Despite multiple freeze-thaw cycles, no significant degradation was observed under colder conditions. Our findings suggest that -20 °C storage is a feasible and effective approach for preserving nucleic acid integrity in FFPE tissues. Although limited by a small sample size (n = 4), this study provides practical insights into tissue archiving strategies and supports selective implementation of refrigerated storage for long-term molecular analysis.

Nationwide survey on HER2 and PD-L1 testing practices in gastric cancer across Japan

BACKGROUND

Since HER2 and PD-L1 testing are key to selecting drugs for first-line treatments in advanced gastric cancer, evaluating differences in these tests among institutions is necessary to standardize treatment.

METHODS

A questionnaire survey was conducted targeting institutions certified by the Japanese Gastric Cancer Association.

RESULTS

Responses were obtained from 155 institutions. Most institutions performed HER2 testing in-house, while PD-L1 tests were largely outsourced. HER2 scores and PD-L1 CPS rates showed greater variability across institutions than anticipated. In the pre-analytic phase, 10% neutral buffered formalin was commonly used, with fixation practices generally following guidelines. Overall, the impact of fixation-related factors was limited, but in surgical specimens, longer fixation was associated with a higher proportion of score 0/1+ and a lower proportion of score 3+. When examining HER2 scores by institution, if a particular score had a high (or low) frequency in biopsy, the same trend was also seen in surgical specimens.

CONCLUSIONS

These findings suggest that not only factors related to specimen preparation, but also biases in evaluation criteria among pathologists may contribute to the significant variability among institutions. Standardization of pre- and post-analytic phases, coupled with appropriate training, is essential to achieve consistent gastric cancer therapy.

Real-world data analysis for factors influencing the quality check status in FoundationOne CDx cancer genomic profiling tests

Comprehensive genomic profiling (CGP) testing is used worldwide for personalized cancer treatment. Unstained slides from formalin-fixed paraffin-embedded (FFPE) blocks are required for tissue-based CGP testing. However, the use of low quality FFPE specimens can result in testing failure or invalid results. Although several previous studies have indicated that the quality of genomic testing is affected by various factors, the factor(s) that has the greatest influence on CGP testing has not been well studied in real-world data. Thus, we conducted a large-scale multi-institutional study in Hiroshima, Japan to investigate the factors associated with quality check status in FoundationOne CDx CGP testing using real-world data from 1,204 participants from an area with a population of approximately 2.7 million. This study revealed low percentage of tumor nuclei in FFPE specimen, long-term storage of FFPE block, and pancreatic cancer as independent risk factors for qualified status. Of the three factors, percentage of tumor nuclei had the largest effect on quality check status, while the magnitudes of the effects of storage time of FFPE or pancreatic cancer were minor. Collectively, our real-world data indicate that tumor purity is the most important factor for successful CGP, and we would suggest greater than 35% as an ideal percentage of tumor nuclei for CGP submission.

Effective Preparation of FFPE Tissue Samples for Preserving Appropriate Nucleic Acid Quality for Genomic Analysis in Thyroid Carcinoma

Formalin-fixed paraffin-embedded (FFPE) tissue samples are important for genomic analysis of thyroid carcinomas, particularly for various molecularly targeted therapies. Therefore, this study developed and validated a technique for preparing FFPE tissue samples that preserves nucleic acid quality, which is fundamental for precise genomic analysis, more effectively than conventional methods. We analyzed surgically resected thyroid gland tumors, lymph node metastases, and separately fixed tumor samples to optimize formalin fixation and assess the influence of specimen type and preparation methods on nucleic acid quality. We assessed several quality indicators, including the DNA integrity number, cycle threshold ratio, RNA integrity number, and DV200. Separately fixed tumor samples consistently exhibited higher DNA and RNA quality than conventionally processed samples. Additionally, lymph node metastases often exhibit nucleic acid quality matching or exceeding that of thyroid gland tumors, highlighting their potential reliability for genomic analysis. These findings suggest the utility of various specimen types for the comprehensive genetic profiling of thyroid carcinomas. In conclusion, this study demonstrated that preparing separately fixed tumor samples is an effective method for preserving DNA and RNA quality for genomic analyses. Biopsy punches enable specimen collection at various facilities, including those without the ability to handle frozen specimens. This contributes to the development of a method for obtaining high-quality pathological samples that can be widely used in general medical practice. Moreover, lymph node metastases often exhibit nucleic acid quality equal to or superior to that of thyroid gland tumors, highlighting their potential as acceptable sources for genomic analyses.

All-in-one bimodal DNA and RNA next-generation sequencing panel for integrative diagnosis of glioma

Previously, we constructed a DNA-based next-generation sequencing (NGS) panel for an integrated diagnosis of gliomas according to the 2021 World Health Organization classification system. The aim of the current study was to evaluate the feasibility of a modified panel to include fusion gene detection via RNA-based analysis. Using this bimodal DNA/RNA panel, we analyzed 210 cases of gliomas and others to identify fusion genes in addition to gene alterations, including TERT promoter (TERTp) mutation and 1p/19q co-deletion, in formalin-fixed paraffin-embedded tissues. Of the 210 patients, fusion genes were detected in tumors of 35 patients. Eighteen of 112 glioblastomas (GBs) harbored fusion genes, including EGFR and FGFR3 fusions. In IDH-mutant astrocytoma, 6 of 30 cases showed fusion genes such as MET and NTRK2 fusions. Eleven molecular GBs and 20 not-elsewhere-classified cases harbored no gene fusions. Other 11 tumors including ependymoma, pilocytic astrocytoma, diffuse hemispheric glioma, infant-type hemispheric glioma, and solitary fibrous tumors exhibited diagnostic fusion genes. Overall, our results suggest that the all-in-one bimodal DNA/RNA panel is reliable for detecting diagnostic gene alterations in accordance with the latest WHO classification. The integrative pathological and molecular strategy could be valuable in confirmation of diagnosis and selection of treatment options for brain tumors.

Adequacy of EUS-guided fine-needle aspiration and fine-needle biopsy for next-generation sequencing in pancreatic malignancies: A systematic review and meta-analysis

Background and Objectives

A majority of pancreatic malignancies are unresectable at the time of presentation and require EUS-guided fine-needle aspiration or fine-needle biopsy (EUS-FNA/FNB) for diagnosis. With the advent of precision therapy, there is an increasing need to use EUS-FNA/FNB sample for genetic analysis. Next-generation sequencing (NGS) is a preferred technology to detect genetic mutations with high sensitivity in small specimens. We performed a meta-analysis to evaluate the adequacy of EUS-FNA/FNB for NGS in pancreatic malignancies.

Methods

PubMed, Embase, Cochrane Library, and Web of Science were searched from database inception to November 11, 2023. The primary outcome was the proportion of sufficient sample acquired by EUS-FNA/FNB in pancreatic malignancies for NGS. Secondary outcomes were the proportion of sufficient sample for NGS in pancreatic ductal adenocarcinoma (PDAC) and the detection rates of mutations in KRAS, TP53, CDKN2A, and SMAD4 and actionable mutations in PDAC. The pooled proportions were calculated using a random-effects model. Potential sources of heterogeneity were investigated with subgroup analyses and meta-regression.

Results

Twenty studies with 881 samples were included. The pooled adequacy of EUS-FNA/FNB sample for NGS was 89.9% (95% CI, 80.8%-96.7%) in pancreatic malignancies and 92.0% (95% CI, 81.3%-98.8%) in PDAC. Screening sample suitability before NGS testing was associated with lower adequacy in subgroup analysis (79.7% vs. 98.4%, P = 0.001). The pooled prevalences of mutations in KRAS, TP53, CDKN2A, and SMAD4 in PDAC were 87.4% (95% CI, 83.2%-91.2%), 62.6% (95% CI, 53.2%-71.7%), 20.6% (95% CI, 11.9%-30.8%), and 19.4% (95% CI, 11.2%-29.1%), respectively. The pooled prevalence of potentially actionable mutations in PDAC was 14.5% (95% CI, 8.2%-22.0%).

Conclusions

In the majority of cases, EUS-FNA/FNB can acquire adequate sample for NGS and identify tumor-specific mutations in patients with pancreatic malignancies. Strict pre-analysis screening criteria may negatively impact the sample adequacy and the success rate for NGS.

[Times and conditions of storage of samples in anatomic pathology. Recommendations of the Spanish Society of Anatomic Pathology (SEAP) part 1: samples for diagnosis]

INTRODUCTION

The correct storage of specimens in the Pathology service is of vital importance for patient safety. However, there are no clear recommendations as regarding how long samples should be stored for a minimum period.

MATERIAL AND METHODS

A working group of the Spanish Society of Anatomic Pathology has reviewed a series of recommendations established in the literature and after two rounds of consultations and a discussion and voting phase has established a series of storage time proposals.

RESULTS

Each of the proposals is presented with the data found in the literature and sometimes offers definitions and exceptions to the proposal.

CONCLUSION

These recommendations, which are minimums, establish a period of at least 10 years for paraffin embedded blocks (including cell blocks), histological preparations, general cytology, pathologic cervico-vaginal cytology and electron microscopy blocks; at least 3 years for cervico-vaginal cytology, 5 years for extracted nucleic acids, at least 4 weeks for tissue in formalin and from the time of diagnosis for liquid cytology material and fluids.

Guidelines of the Brazilian Society of Surgical Oncology for anatomopathological, immunohistochemical, and molecular testing in female tumors

INTRODUCTION

Precision medicine has revolutionized oncology, providing more personalized diagnosis, treatment, and monitoring for patients with cancer. In the context of female-specific tumors, such as breast, ovarian, endometrial, and cervical cancer, proper tissue collection and handling are essential for obtaining tissue, immunohistochemical (IHC), and molecular data to guide therapeutic decisions.

OBJECTIVES

To establish guidelines for the collection and handling of tumor tissue, to enhance the quality of samples for histopathological, IHC, genomic, and molecular analyses. These guidelines are fundamental in informing therapeutic decisions in cancer treatment.

METHOD

The guidelines were developed by a multidisciplinary panel of renowned specialists between June 12, 2013 and February 12, 2024. Initially, the panel deliberated on critical and controversial topics related to conducting precision medicine studies focusing on female tumors. Subsequently, 22 pivotal topics were identified within the framework and assigned to groups. These groups reviewed relevant literature and drafted preliminary recommendations. Following this, the recommendations were reviewed by the coordinators and received unanimous approval. Finally, the groups made the final adjustments, classified the level of evidence, and ranked the recommendations.

CONCLUSION

The collection of surgical samples requires minimum quality standards to enable histopathological, IHC, genomic, and molecular analyses. These analyses provide crucial data for informing therapeutic decisions, significantly impacting potential survival gains for patients with female tumors.

RNA-Seq Analysis in Non-Small Cell Lung Cancer: What Is the Best Sample from Clinical Practice?

RNA-based next-generation sequencing (RNA-seq) represents the gold standard for detecting gene fusion in non-small cell lung cancer (NSCLC). Despite this, RNA instability makes the management of tissue samples extremely complex, resulting in a significant number of test failures with missing data or the need to switch to other techniques. In the present study, we analyzed pre-analytical variables in 140 tumor tissue samples from patients affected by NSCLC to detect features that increase the chances of successful RNA-seq. We found that the success rate of the analysis positively correlates with the RNA concentration and fragmentation index. Interestingly, small biopsies were more suitable samples than surgical specimens and cell blocks. Among surgical specimens, wedge resections demonstrated better results than lobectomy. Moreover, samples stored for less than 30 days (1 month) had a better chance of success than older samples. Defining the role of pre-analytical variables in RNA-seq allows the detection of more suitable samples for analysis and more effective planning of molecular-based diagnostic approaches in NSCLC.

The Advantage of Targeted Next-Generation Sequencing over qPCR in Testing for Druggable EGFR Variants in Non-Small-Cell Lung Cancer

The emergence of targeted therapies in non-small-cell lung cancer (NSCLC), including inhibitors of epidermal growth factor receptor (EGFR) tyrosine kinase, has increased the need for robust companion diagnostic tests. Nowadays, detection of actionable variants in exons 18-21 of the EGFR gene by qPCR and direct DNA sequencing is often replaced by next-generation sequencing (NGS). In this study, we evaluated the diagnostic usefulness of targeted NGS for druggable EGFR variants testing in clinical NSCLC material previously analyzed by the IVD-certified qPCR test with respect to DNA reference material. We tested 59 NSCLC tissue and cytology specimens for EGFR variants using the NGS 'TruSight Tumor 15' assay (Illumina) and the qPCR 'cobas EGFR mutation test v2' (Roche Diagnostics). The sensitivity and specificity of targeted NGS assay were evaluated using the biosynthetic and biological DNA reference material with known allelic frequencies (VAF) of EGFR variants. NGS demonstrated a sufficient lower detection limit for diagnostic applications (VAF < 5%) in DNA reference material; all EGFR variants were correctly identified. NGS showed high repeatability of VAF assessment between runs (CV% from 0.02 to 3.98). In clinical material, the overall concordance between NGS and qPCR was 76.14% (Cohen's Kappa = 0.5933). The majority of discordant results concerned false-positive detection of EGFR exon 20 insertions by qPCR. A total of 9 out of 59 (15%) clinical samples showed discordant results for one or more EGFR variants in both assays. Additionally, we observed TP53 to be a frequently co-mutated gene in EGFR-positive NSCLC patients. In conclusion, targeted NGS showed a number of superior features over qPCR in EGFR variant detection (exact identification of variants, calculation of allelic frequency, high analytical sensitivity), which might enhance the basic diagnostic report.

Proteomic profiling of FFPE specimens: Discovery of HNRNPA2/B1 and STT3B as biomarkers for determining formalin fixation durations

Recent advancements in proteomics technologies using formalin-fixed paraffin-embedded (FFPE) samples have significantly advanced biomarker discovery. Yet, the effects of varying sample preparation protocols on proteomic analyses remain poorly understood. We analyzed mouse liver FFPE samples that varied in fixatives, fixation duration, and storage temperature using LC/MS. We found that variations in fixation duration significantly affected the abundance of specific proteins, showing that HNRNPA2/B1 demonstrated a significant decrease in abundance in samples fixed for long periods, whereas STT3B exhibited a significant increase in abundance in samples fixed for long durations. These findings were supported by immunohistochemical analysis across liver, spleen, and lung tissues, demonstrating a significant decrease in the nuclear staining of HNRNPA2/B1 in long-duration acid formalin(AF)-fixed FFPE samples, and an increase in cytoplasmic staining of STT3B in long-duration neutral buffered formalin-fixed liver and lung tissues and granular staining in all long-duration AF-fixed FFPE tissue types. Similar trends were observed in the long-duration fixed HeLa cells. These results demonstrate that fixation duration critically affects the proteomic integrity of FFPE samples, emphasizing the urgent need for standardized fixation protocols to ensure consistent and reliable proteomic data. SIGNIFICANCE: The quality of FFPE samples is primarily influenced by the fixation and storage conditions. However, previous studies have mainly focused on their impact on nucleic acids and the extent to which different fixation conditions affect changes in proteins has not been evaluated. In addition, to our knowledge, proteomic research focusing on differences in formalin fixation conditions has not yet been conducted. Here, we analyzed FFPE samples with different formalin fixation and storage conditions using LC/MS and evaluated the impact of different fixation conditions on protein variations. Our study unequivocally established formalin fixation duration as a critical determinant of protein variation in FFPE specimens and successfully identified HNRNPA2/B1 and STT3B as potential biomarkers for predicting formalin fixation duration for the first time. The study findings open new avenues for quality assessment in biomedical research and diagnostics.

Clinical application of targeted tumour sequencing tests for detecting ERBB2 amplification and optimizing anti-HER2 therapy in gastric cancer

BACKGROUND

Evaluation of human epidermal growth factor receptor 2 (HER2) overexpression caused by erb-b2 receptor tyrosine kinase 2 (ERBB2) amplification (AMP) by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) is essential for treating unresectable metastatic gastric cancer (GC). A targeted tumour sequencing test enables comprehensive assessment of alterations in cancer-related genes, including ERBB2. This study aimed to evaluate the concordance between the targeted tumour sequencing test and IHC/FISH for detecting HER2-positive GC and to clarify the significance of ERBB2 AMP and concomitant genetic alterations in HER2 downstream pathways (DPs) in anti-HER2 therapy for unresectable metastatic GC patients.

METHODS

ERBB2 copy number alteration (CNA) was examined via a targeted tumour sequencing test in 152 formalin-fixed paraffin-embedded (FFPE) GC tissues. ERBB2 CNA was compared to HER2 status evaluated by IHC/FISH in FFPE block sections, which were identical to those subjected to the targeted tumour sequencing test. Treatment outcomes of anti-HER2 therapy in 11 patients with unresectable metastatic GC was evaluated.

RESULTS

ERBB2 AMP (≥ 2.5-fold change) was detected by the targeted tumour sequencing test in 15 patients (9.9%), and HER2 positivity (IHC 3 + or IHC 2+/FISH positive) was detected in 21 patients (13.8%). The overall percent agreement, positive percent agreement, negative percent agreement and Cohen's kappa between ERBB2 CNA and HER2 status were 94.7%, 66.7%, 99.2% and 0.75, respectively. Progression-free survival for trastuzumab therapy in patients with ERBB2 AMP was significantly longer than that in patients with no ERBB2 AMP detected by the targeted tumour sequencing test (median 14 months vs. 4 months, P = 0.007). Treatment response to trastuzumab therapy was reduced in patients with ERBB2 AMP and concomitant CNAs of genes in HER2 DPs. One patient with ERBB2 AMP and concomitant CNAs of genes in HER2 DPs achieved a durable response to trastuzumab deruxtecan as fourth-line therapy.

CONCLUSIONS

A targeted tumour sequencing test is a reliable modality for identifying HER2-positive GC. ERBB2 AMP and concomitant genetic alterations detected through the targeted tumour sequencing test are potential indicators of treatment response to trastuzumab therapy. The targeted tumour sequencing test has emerged as a plausible candidate for companion diagnostics to determine indications for anti-HER2 therapy in the era of precision medicine for GC.

An approach for improvement of the accuracy of cancer gene panel testing

BACKGROUND

Tissue-based comprehensive genomic profiling (CGP) is increasingly being employed for genotype-directed therapies in patients with advanced cancer. However, tissue availability may limit their potential applications. In Japan, the cost of cancer gene panel tests is covered by public insurance for patients diagnosed with advanced solid tumors once in their lifetime. Therefore, it is essential to improve the success rate (reportability) and accuracy of CGP tests. The purpose of this study was to identify the factors associated with efficient and accurate CGP testing using relevant information obtained from real-world data.

METHODS

This study included 159 samples analyzed using tumor-only panel FoundationOne® CDx cancer genome profiling (F1CDx) and 85 samples analyzed using matched-pair panel OncoGuide™ NCC Oncopanel system (NCCOP) at St. Marianna University Hospital. Sample characteristics (fixation conditions, storage period, histology, tumor cell ratio, and genomic tumor cell content), CGP performance, and quality control status were evaluated across all 244 tested samples.

RESULTS

In 237/244 samples (97.1%), CGP testing results were successfully obtained [F1CDx, 99.4% (158/159) and NCCOP, 92.9% (79/85)]. An increased number of fibroblasts, inflammatory cells, and necrotic tumor cells, long-term storage, and/or prolonged fixation of tissue sections were involved in the unreported results and/or qualified CGP results. In addition, a negative correlation between median insert size values and ΔΔCq was observed in the NCCOP system.

CONCLUSION

We identified various factors associated with efficient and accurate CGP testing using relevant information obtained from real-world data, suggesting that thorough selection and preparation of tissue sections could optimize CGP and maximize useful information.

The Current Achievements of Multi-Gene Panel Tests in Clinical Settings for Patients with Non-Small-Cell Lung Cancer

Some multi-gene panel tests have been implemented in clinical settings to guide targeted therapy in non-small-cell lung cancer (NSCLC) in Japan. The current performance of multi-gene panel tests under the condition that the Oncomine Dx Target Test (ODxTT) and Amoy Dx® Pan Lung Cancer PCR panel (AmoyDx-multi) are available remains relatively unknown. We retrospectively reviewed consecutive patients with NSCLC, whose FFPE samples were considered for genetic testing. We assessed the submission rates, the success rates, and the driver oncogene detection rates of multi-gene panel tests. A total of 225 patients were histologically newly diagnosed with NSCLC or diagnosed with a recurrence of NSCLC without a previous multi-gene panel test at our institution. Among the 225 patients, the FFPE samples of 212 patients (94.2%) were submitted for multi-gene panel testing, including 191 samples (84.9%) for the ODxTT and 21 samples (9.3%) for the AmoyDx-multi. Among the 212 samples submitted to multi-gene panel tests, the success rate was 99.5% (211/212). The detection rate of driver oncogene alterations for all histologies was 52.4% (111/212), and that for adenocarcinoma was 69.7% (106/152). A favorable submission rate and success rate of multi-gene panel tests were shown, along with a favorable detection rate in recent clinical settings.

Immunohistochemical and molecular profiles of heterogeneous components of metaplastic breast cancer: a squamous cell carcinomatous component was distinct from a spindle cell carcinomatous component

Metaplastic breast carcinoma (MBC), a category of breast cancer, includes different histological types, which are occasionally mixed and heterogeneous. Considering the heterogeneity of cancer cells in a tumour mass has become highly significant, not only from a biological aspect but also for clinical management of recurrence. This study aimed to analyse the immunohistochemical and molecular profiles of each MBC component of a tumour mass. Twenty-five MBC tumours were histologically evaluated, and the most frequent MBC component (c) was squamous cell carcinoma (SCC), followed by spindle cell carcinoma (SpCC). A total of 69 components of MBC and non-MBC in formalin-fixed paraffin-embedded sections were examined for 7 markers by immunohistochemistry. SCC(c) were significantly PTEN negative and CK14 positive, and SpCC(c) were significantly E-cadherin negative and vimentin positive. Multivariate analyses revealed that immunohistochemical profiles of normal/intraductal (IC)(c), no special type (NST)(c), and MBC(c) differed; moreover, SCC(c) and SpCC(c) were distinctly grouped. PTEN gene mutation was detected only in SCC(c) (2/7), but not in SpCC(c). Next-generation sequence analyses for 2 cases with tumours containing SCC(c) demonstrated that PTEN gene mutation increased progressively from IC(c) to NST(c) to SCC(c). In conclusion, the immunohistochemical and molecular profiles of the SCC(c) of MBC are distinct from those of the SpCC(c).

Development of a rapid and comprehensive genomic profiling test supporting diagnosis and research for gliomas

A prompt and reliable molecular diagnosis for brain tumors has become crucial in precision medicine. While Comprehensive Genomic Profiling (CGP) has become feasible, there remains room for enhancement in brain tumor diagnosis due to the partial lack of essential genes and limitations in broad copy number analysis. In addition, the long turnaround time of commercially available CGPs poses an additional obstacle to the timely implementation of results in clinics. To address these challenges, we developed a CGP encompassing 113 genes, genome-wide copy number changes, and MGMT promoter methylation. Our CGP incorporates not only diagnostic genes but also supplementary genes valuable for research. Our CGP enables us to simultaneous identification of mutations, gene fusions, focal and broad copy number alterations, and MGMT promoter methylation status, with results delivered within a minimum of 4 days. Validation of our CGP, through comparisons with whole-genome sequencing, RNA sequencing, and pyrosequencing, has certified its accuracy and reliability. We applied our CGP for 23 consecutive cases of intracranial mass lesions, which demonstrated its efficacy in aiding diagnosis and prognostication. Our CGP offers a comprehensive and rapid molecular profiling for gliomas, which could potentially apply to clinical practices and research primarily in the field of brain tumors.

Efficacy of endoscopic ultrasound-guided tissue acquisition using stereo-microscopic on-site evaluation for possible comprehensive genome profile in patients with advanced pancreatic cancer

BACKGROUND AND AIM

Stereomicroscopic on-site evaluation (SOSE) is a rapid evaluation method for endoscopic ultrasound-guided tissue acquisition (EUS-TA) with a high diagnostic sensitivity when the stereomicroscopically visible white core (SVWC) cut-off value (≥ 11 mm) is met. We prospectively examined the association between SVWCs and the adequacy of tissue specimens, assuming subsequent comprehensive genome profiling (CGP).

METHODS

This study included 66 consecutive patients with suspected unresectable pancreatic cancer who underwent EUS-TA. The primary endpoint was the frequency of combined samples with ≥ 20% tumor cell content that met over twice the SVWC (T-SVWC) cut-off value, achieved through multiple punctures. The secondary endpoints were the number of punctures, the percentage of SVWC cut-off values, adverse events, the positive diagnosis rate, and the tissue section area.

RESULTS

The median number of EUS-TA punctures for suspected unresectable pancreatic cancer was 3 (range, 3-4); SVWC and T-SVWC cut-off values were obtained in 171/206 specimens and 65/66 patients, respectively. There were no EUS-TA-related adverse events. The positive diagnosis rate of EUS-TA was 95.5%. Among the 63 patients meeting the T-SVWC cut-off value in pathological diagnoses, the median tumor cell content was 40% (range, 5-80%), with 57 patients having tumor cell content ≥ 20%. The median tissue section area was 15 (range, 3-40) mm2.

CONCLUSIONS

When performing EUS-TA for unresectable pancreatic cancer with the intention of subsequent CGP, obtaining a high tumor cell content (≥ 20%) by assessing the T-SVWC cut-off value via SOSE may serve as a novel indicator for on-site estimation of CGP suitability for EUS-TA specimens.

Analysis of quality metrics in comprehensive cancer genomic profiling using a dual DNA-RNA panel

Background

The nucleic acid quality from formalin-fixed paraffin-embedded (FFPE) tumor vary among samples, resulting in substantial variability in the quality of comprehensive cancer genomic profiling tests. The objective of the study is to investigate how nucleic acid quality affects sequencing quality. We also examined the variations in nucleic acid quality among different hospitals or cancer types.

Methods

Three nucleic acid quality metrics (ddCq, Q-value, and DV200) and five sequencing quality metrics (on-target rate, mean depth, coverage uniformity, target exon coverage, and coverage of the housekeeping gene) were examined using 585 samples from the Todai OncoPanel, a dual DNA-RNA panel.

Results

In the DNA panel, ddCq served as an indicator of sequencing depth and Q-value reflected the uniformity of sequencing across different regions. It was essential to have favorable values not only for ddCq but also for Q-value to obtain ideal sequencing results. For the RNA panel, DV200 proved to be a valuable metric for assessing the coverage of the housekeeping genes. Significant inter-hospital differences were observed for DNA quality (ddCq and Q-value), but not for RNA quality (DV200). Differences were also observed among cancer types, with Q-value being the lowest in lung and the highest in cervix, while DV200 was the highest in lung and the lowest in bowel.

Conclusions

We demonstrated distinct characteristics and high predictive performances of ddCq, Q-value, and DV200. Variations were observed in the nucleic acid quality across hospitals and cancer types. Further study is warranted on preanalytical factors in comprehensive cancer genomic profiling tests.

Clinical utility of the Oncomine Dx Target Test multi-CDx system and the possibility of utilizing those original sequence data

BACKGROUND

Companion diagnostic tests play a crucial role in guiding treatment decisions for patients with non-small cell lung cancer (NSCLC). The Oncomine Dx Target Test (ODxTT) Multi-CDx System has emerged as a prominent companion diagnostic method. However, its efficacy in detecting driver gene mutations, particularly rare mutations, warrants investigation.

AIMS

This study aimed to assess the performance of the ODxTT in detecting driver gene mutations in NSCLC patients. Specifically, we aimed to evaluate its sensitivity in detecting epidermal growth factor receptor (EGFR) mutations, a key determinant of treatment selection in NSCLC.

MATERIALS AND METHODS

We conducted a retrospective analysis of NSCLC patients who underwent testing with the ODxTT at Keio University Hospital between May 2020 and March 2022. Patient samples were subjected to both DNA and RNA tests. Driver gene mutation status was assessed, and instances of missed mutations were meticulously examined.

RESULTS

Of the 90 patients, five had nucleic acid quality problems, while 85 underwent both DNA and RNA tests. Driver gene mutations were detected in 56/90 (62.2%) patients. Of the 34 patient specimens, driver mutations were not detected using the ODxTT; however, epidermal growth factor receptor (EGFR) mutations were detected using polymerase chain reaction-based testing in two patients, and a KRAS mutation was detected by careful examination of the sequence data obtained using the ODxTT in one patient. For the above three cases, carefully examining the gene sequence information obtained using the ODxTT could identify driver mutations that were not mentioned in the returned test results. Additionally, we confirmed comparable instances of overlook results for EGFR mutations in the dataset from South Korea, implying that this type of oversight could occur in other countries using the ODxTT. EGFR mutation was missed in ODxTT in Japan (6.3%, 2/32), South Korea (2.0%, 1/49), and overall (3.7%, 3/81).

CONCLUSION

Even if sufficient tumor samples are obtained, rare EGFR mutations (which are excluded from the ODxTT's genetic mutation list) might not be detected using the current ODxTT system due to the program used for sequence analysis. However, such rare EGFR mutations can still be accurately detected on ODxTT's sequence data using next-generation sequencing.

Impact of the quality of resected thyroid cancer tissue sample on next-generation sequencing testing

Activating rearranged during transfection (RET) proto-oncogene alterations can be identified using next-generation sequencing (NGS) of tumor DNA/RNA. We assessed factors associated with NGS (Oncomine Dx Target Test [ODxTT]) success for resected thyroid cancer (TC) specimens, including sample age, processing conditions, and DNA/RNA quality. TC samples were from three Japanese hospitals, with sample age <1-<10 years, fixative 10%/15% neutralized buffered formalin (NBF), and fixation time ≤48 h/>48 h-≤72 h. NGS success rate was defined as the percentage of samples returning validated NGS results (RET fusion-positive/negative [RNA] or RET mutation-positive/negative [DNA], detected using ODxTT). DNA/RNA quality was assessed with indexes based on electrophoresis (DNA/RNA integrity number, DV200 ) and quantitative polymerase chain reaction (DNA/RNA integrity score [ddCq/ΔCq]). NGS success rate (N = 202) was 90%/93% (DNA/RNA) overall, 98%-100% (DNA and RNA) for samples <3 years old, and 91% (DNA and RNA) for samples ≥3-<5 years old fixed in 10% NBF for ≤48 h. Multivariate logistic regression analysis identified ddCq and ΔCq as significant predictors of DNA and RNA NGS success rates, respectively. Quality assessment of nucleic acid extracted from archival tissue samples is important for achieving high NGS success rates in clinical practice, especially for samples ≥3 years old.

Clinical practice guidelines for molecular tumor markers, 2nd edition review part 1

With advances in gene and protein analysis technologies, many target molecules that may be useful in cancer diagnosis have been reported. Therefore, the "Tumor Marker Study Group" was established in 1981 with the aim of "discovering clinically" useful molecules. Later, the name was changed to "Japanese Society for Molecular Tumor Marker Research" in 2000 in response to the remarkable progress in gene-related research. Currently, the world of cancer treatment is shifting from the era of representative tumor markers of each cancer type used for tumor diagnosis and treatment evaluation to the study of companion markers for molecular-targeted therapeutics that target cancer cells. Therefore, the first edition of the Molecular Tumor Marker Guidelines, which summarizes tumor markers and companion markers in each cancer type, was published in 2016. After publication of the first edition, the gene panel testing using next-generation sequencing became available in Japan in June 2019 for insured patients. In addition, immune checkpoint inhibitors have been indicated for a wide range of cancer types. Therefore, the 2nd edition of the Molecular Tumor Marker Guidelines was published in September 2021 to address the need to revise the guidelines. Here, we present an English version of the review (Part 1) of the Molecular Tumor Marker Guidelines, Second Edition.

Direct specimen collection during routine operation improves nucleic acid quality in genetic analysis samples for head and neck tumors: A retrospective study

The nucleic acid integrity of head and neck squamous cell carcinoma (HNSCC) samples is poor, and the material available for genetic analysis is limited. Therefore, to expand the effectiveness of personalized medicine in patients with HNSCC, a new sampling method is needed. In total, 128 samples from 44 patients with HNSCC were studied: 32 genetic analysis samples (GASs) collected as 5 × 5 × 5 mm tissue fragments from resected large tumors and immediately embedded in a small formalin bottle within 10 min (i.e., the ischemic time), 43 primary tumor components (primary), 14 decalcified tumor (DC) samples, 32 metastatic tumors in lymph nodes (LNs), and 7 parakeratinized components (PKCs). The nucleic acid quality in the GAS, primary, DC, LN, and PKC groups was compared and next-generation sequencing (NGS) was performed. DNA integrity number and percentage of RNA fragments with > 200 nucleotides were significantly higher in the GAS group than those in the other groups. RNA integrity number decreased first in LN, followed by GAS, primary, and DC. No significant differences were observed in DIN, RIN and DV200 among the PKC, primary and LN. Following methyl green-pyronin staining, preserved DNA and RNA were not visualized in DC samples. Most NGS metrics did not differ significantly among primary, LN, and PKC samples. In conclusion, GASs should be collected during routine hospital activities. When the volume of viable materials is limited, PKCs should be considered for genetic analysis.

Influence of formalin fixation duration on RNA quality and quantity from formalin-fixed paraffin-embedded hepatocellular carcinoma tissues

Analyzing RNA samples from formalin-fixed paraffin-embedded (FFPE) tissues is essential for precision medicine. We investigated RNA quantity and quality from FFPE tumor tissues fixed in formalin for various times and compared sequencing metrics from next-generation sequencing (NGS). Hepatocellular carcinoma (HCC) tissues were fixed in 10% neutral buffered formalin (1-240 h) and FFPE blocks were prepared. Total RNA was extracted, and the quantity and quality were assessed using the NanoDrop, Qubit and Bioanalyzer. After preparing sequencing libraries, NGS was performed on the Oncomine Dx Multi-CDx system. Total RNA yields of all samples met the threshold required for NGS, but longer fixation times resulted in decreased total RNA and long RNA fragment (>200 nt) yields. NGS analysis showed fewer sequencing reads of internal control genes from RNA with longer fixation times. RNA extracted from FFPE blocks stored for 500 days had reduced RNA yield and quality compared with RNA obtained from FFPE blocks prepared immediately. In conclusion, short and over-fixation should be avoided because of their negative impact on sequencing quality. Fixation process should be finished promptly within recommended guidelines (6-72 h) for cancer patients.

Suitability of respiratory endoscopy for sampling malignant thoracic tumors for comprehensive genomic profiling

Comprehensive genomic profiling (CGP) is implemented to detect actionable gene aberrations and design matched therapies. Although malignant thoracic tumors are commonly detected through respiratory endoscopy, it is questionable whether the small specimens obtained thereof are sufficient for CGP. Therefore, this study aimed to investigate the suitability of respiratory endoscopy for sampling primary and metastatic thoracic tumors for CGP. Patients whose specimens were collected through respiratory endoscopy and assessed by pathologists to determine their suitability for CGP at our institution between June 2019 and May 2022 were reviewed retrospectively. The suitability of each procedure as a sampling technique for CGP and, in the cases actually analyzed, the distribution of the detected gene aberration were assessed. In total, 122 patients were eligible for analysis; the median age was 61 (range, 29-86) years, and 71 (58.2%) patients were male. Primary intrathoracic tumors were found in 91 (74.6%) cases, including 84 (68.9%) primary lung cancers; the remaining thoracic metastases of extrathoracic origin included various types. The suitability rates of specimens obtained using conventional bronchoscopy with and without cryobiopsy, endobronchial ultrasound-guided transbronchial needle aspiration, and medical thoracoscopy were 82.8% (24/29), 70.4% (19/27), 72.9% (35/48), and 100% (18/18), respectively. Of the 96 cases judged suitable, 83 were subjected to CGP, and all but one were successfully analyzed. Finally, 47 (56.6%) patients had at least one actionable gene aberration and eight (9.6%) were treated with the corresponding targeted therapies. In conclusion, specimens obtained through respiratory endoscopy are suitable for CGP; medical thoracoscopy and cryobiopsy in conventional bronchoscopy are particularly useful.

Constant small-cell changes and variable LEF1 expression in DUSP22-rearranged primary cutaneous anaplastic large-cell lymphoma: Analysis of the repeated biopsies of three patients

DUSP22-rearranged primary cutaneous anaplastic large-cell lymphoma (pcALCL) has a biphasic histological pattern defined by large dermal atypical lymphocytes and epidermotropic small lymphocytes resembling pagetoid reticulosis, but the positivity rate of the biphasic pattern in DUSP22-rearranged pcALCL is unknown. Immunohistochemically, LEF1 expression in >75% of tumor cells is associated with DUSP22-rearrangement (DUSP22-R) in systemic ALCL. However, whether this association applies to pcALCL remains unclear. To analyze these pathological clues for screening DUSP22-R, we reviewed 11 skin biopsies from three patients with DUSP22-rearranged pcALCL. All specimens showed a biphasic pattern, of which three showed nonpagetoid infiltration of the epidermis. In all lesions, small-cell changes of tumor cells were observed not only within the epidermis but also under the epidermis. LEF1 positivity rates varied by lesion (range: 30%-90%, mean: 59.6%) with only three patients expressing LEF1 in more than 75% of tumor cells. In conclusion, the biphasic pattern was a constant finding in DUSP22-rearranged pcALCL, but it was not always pagetoid reticulosis-like. The recognition of small-cell change outside the epidermis may be helpful in diagnosing DUSP22-rearranged pcALCL. However, LEF1 expression was variable and its diagnostic usefulness may be limited.

Diagnostic utility of DNA integrity number as an indicator of sufficient DNA quality in next-generation sequencing-based genomic profiling

OBJECTIVES

DNA integrity number (DIN) is a metric for assessing DNA degradation, calculated based on electrophoresis using the Agilent TapeStation System. The utility of DIN as a diagnostic indicator of sufficient DNA quality in clinical next-generation sequencing (NGS) has not been well described.

METHODS

We evaluated the DINs of 166 tumor formalin-fixed, paraffin-embedded (FFPE) tissue samples submitted for 124-gene panel sequencing. We also investigated a new metric on the electropherogram that could improve the predictive accuracy of the DIN.

RESULTS

A DIN cutoff of 2.5 discriminated samples with successful analysis (n = 143) from samples with failed analysis (n = 23), with a sensitivity of 0.84 and a specificity of 0.78 (area under the curve [AUC] = 0.88). The DIN was positively correlated with the mean coverage (r = 0.72, P < .0001) but could not discriminate success from failure when the DIN was below 2.5 (negative predictive value, 0.44). We introduced a new metric, the peak/base ratio, that distinguished success from failure with higher accuracy than the DIN (cutoff = 1.6; sensitivity = 0.98, specificity = 0.83, and AUC =0.96).

CONCLUSIONS

To predict successful NGS, the DNA quality of FFPE tissue can be easily and reliably assessed using the DIN and peak/base ratio.

Evaluation of appropriate conditions for Oncomine DxTT testing of FFPE specimens for driver gene alterations in non-small cell lung cancer

BACKGROUND

The Oncomine Dx Target Test Multi-CDx System (ODxTT) is a next-generation sequencing panel approved as a companion diagnostic for drugs targeted to corresponding gene alterations in non-small cell lung cancer. However, appropriate slide conditions for ODxTT have remained unclear.

METHODS

We focused on the production of the number of tumor cells on a formalin-fixed paraffin-embedded (FFPE) section and the number of prepared slides, designated the TS value, and determined a TS value of ≥4000 as a target slide condition for ODxTT. We evaluated the impact of this condition on ODxTT testing with tumor specimens found to have a TS of <4000 (n = 23) or a TS of ≥4000 (n = 142).

RESULTS

A positive correlation was apparent between the TS value and the concentrations of both DNA and RNA. Among the 142 samples with a TS of ≥4000, a sufficient concentration of DNA or RNA for ODxTT analysis was achieved in 100% and 98% samples, respectively. Among samples explored for driver gene alterations after determination of the target slide condition (TS ≥4000), most (84.9%) had a TS of ≥4000 and were submitted for ODxTT analysis.

CONCLUSION

Our findings indicate that a TS of ≥4000 is a feasible and relevant criterion for ODxTT testing, and its adoption should help to improve the success rate of such testing in clinical practice.

Nucleic Acid Quality Assessment is Critical to the Success of the Oncomine Dx Target Test for Lung Cancer

BACKGROUND AND OBJECTIVE

The Oncomine Dx Target Test (ODxTT) has been used as a companion diagnostic test for lung cancer. Here, we evaluated whether the amount of nucleic acid and the degree of RNA degradation are related to the success of the ODxTT.

METHODS

This study included 223 samples from 218 patients with lung cancer. For all samples, DNA and RNA concentrations were quantified using Qubit, and the degree of RNA degradation was evaluated using the Bioanalyzer.

RESULTS

Of the 223 samples, 219 samples were successfully analyzed in the ODxTT and four were not. DNA analysis failed in two samples, which were attributed to low DNA concentrations and both were cytology specimens. Meanwhile, RNA analysis failed in the other two samples. These samples had sufficient amounts of RNA, but it was highly degraded with DV200 (the percentage of RNA fragments > 200 base pairs) less than 30. Compared with RNA samples with DV200 ≥ 30, analysis of RNA with DV200 < 30 yielded significantly fewer reads for the internal control genes. This test showed actionable mutations were identified in 38% (83/218) of all patients and in 46.6% (76/163) of patients with lung adenocarcinoma.

CONCLUSIONS

DNA concentration and degree of RNA degradation are key factors determining the success of diagnostic testing by the ODxTT.

Endoscopic Ultrasound-Guided Tissue Acquisition of Pancreaticobiliary Cancer Aiming for a Comprehensive Genome Profile

In recent years, cancer genomic medicine centered on comprehensive genome profile (CGP) analysis has become widely used in the field of pancreatic cancer. Endoscopic ultrasound-guided tissue acquisition (EUS-TA) has played an important role in pancreatic cancer, and recently, more EUS-TA tissue samples are considered for CGP analysis. Differences exist between the Oncoguide NCC Oncopanel System and Foundation One CDx Cancer Genome Profile, which are CGP tests approved by insurance programs in Japan, including the analysis criteria, optimal needle selection for meeting these criteria, and puncture target. It is important to understand not only the specimen collection factors, but also the specimen processing factors that can increase the success rate of CGP testing. Furthermore, cancer genome medicine is expected to enter an era of increasing turbulence in the future, and endoscopists need to respond flexibly to these changes. Herein, we review the current status of cancer genome medicine in pancreatic and biliary tract cancers and cancer gene panel testing using EUS-TA.

Areas of Crush Nuclear Streaming Should Be Included as Tumor Content in the Era of Molecular Diagnostics

Degenerated tissues are frequently observed in malignant tumors, but are not analyzed. We investigated whether nuclear streaming and necrosis samples could be used for genetic analysis to expand the sample pool. A total of 81 samples were extracted from small cell carcinoma and lymphoma FFPE tissue blocks and classified into three histological cohorts: 33 materials with well-preserved tumor morphology, 31 nuclear streaming samples, and 17 necrosis samples. DNA and RNA integrity numbers, percentage of RNA fragments with >200 nucleotides, and next-generation sequencing quality metrics were compared among the cohorts. DNA quality did not significantly differ between nuclear streaming materials and materials with well-preserved morphology, whereas that of the necrosis samples was inferior. RNA quality decreased in the following order: materials with well-preserved morphology > nuclear streaming > necrosis. The sequencing metrics did not differ significantly between the nuclear streaming samples and materials with well-preserved morphology, and reliable variants were detected. The necrosis samples extracted from resections exhibited sequencing failure and showed significantly fewer on-target aligned reads and variants. However, variant allele frequency did not differ among the cohorts. We revelated that DNA in nuclear streaming samples, especially within biopsies, could be used for genetic analysis. Moreover, degenerated non-tumor cells should be counted when evaluating tumor content to avoid misinterpreting the variant allele frequency.

Low-temperature plasma as magic wand to differentiate between the good and the evil

Plasma is the fourth physical state of matter, characterized by an ionized gaseous mixture, after solid, liquid, and gas phases, and contains a wide array of components such as ions, electrons, radicals, and ultraviolet ray. Whereas the sun and thunder are typical natural plasma, recent progress in the electronics enabled the generation of body-temperature plasma, designated as low-temperature plasma (LTP) or non-thermal plasma since the 1990s. LTP has attracted the attention of researchers for possible biological and medical applications. All the living species on earth utilize water as essential media for solvents and molecular transport. Thus, biological application of LTP naturally intervenes water whether LTP is exposed directly or indirectly, where plasma-activated lactate (PAL) is a standard, containing H₂O₂, NO₂^- and other identified molecules. Electron spin resonance and immunohistochemical studies demonstrated that LTP exposure is a handy method to load local oxidative stress. Cancer cells are characterized by persistent self-replication and high cytosolic catalytic Fe(II). Therefore, both direct exposure of LTP and PAL can provide higher damage to cancer cells in comparison to non-tumorous cells, which has been demonstrated in a variety of cancer types. The cell death mode is either apoptosis or ferroptosis, depending on the cancer-type. Thus, LTP and PAL are expected to work as an additional cancer therapy to the established guideline protocols, especially for use in somatic cavities or surgical margins.

Association of Microluminal Structures Assessed by Optical Coherence Tomography With Local Inflammation in Adjacent Epicardial Adipose Tissue and Coronary Plaque Characteristics in Fresh Cadavers

BACKGROUND

Coronary intraplaque microluminal structures (MS) are associated with plaque vulnerability, and the inward progression of vascular inflammation from the adventitia towards the media and intima has also been demonstrated. Therefore, in the present study we investigated the relationships among MS, local inflammation in adjacent epicardial adipose tissue (EAT), and coronary plaque characteristics.

METHODS AND RESULTS

Optical coherence tomography (OCT) revealed MS in the left anterior descending coronary artery in 10 fresh cadaveric hearts. We sampled 30 lesions and subdivided them based on the presence of MS: MS (+) group (n=19) and MS (-) group (n=11). We measured inflammatory molecule levels in the adjacent EAT and percentage lipid volume assessed by integrated backscatter intravascular ultrasound in each lesion. The expression levels of vascular endothelial growth factor B and C-C motif chemokine ligand 2 were significantly higher in the MS (+) group than in the MS (-) group (0.9±0.7 vs. 0.2±0.2 arbitrary units (AU), P=0.04 and 1.5±0.5 vs. 0.6±0.7 AU, P=0.02, respectively). Percentage lipid volume was significantly higher in the MS (+) group than in the MS (-) group (38.7±16.5 vs. 23.7±10.9%, P=0.03).

CONCLUSIONS

Intraplaque MS observed on OCT were associated with lipid-rich plaques and local inflammation in the adjacent EAT. Collectively, these results suggest that local inflammation in the EAT is associated with coronary plaque vulnerability via MS.

Expert Panel Consensus Recommendations on the Use of Circulating Tumor DNA Assays for Patients with Advanced Solid Tumors

Comprehensive genomic profiling is increasingly used to facilitate precision oncology based on molecular stratification. In addition to conventional tissue comprehensive genomic profiling, comprehensive genomic profiling of circulating tumor DNA has become widely utilized in cancer care owing on its advantages, including less invasiveness, rapid turnaround time, and capturing heterogeneity. However, circulating tumor DNA comprehensive genomic profiling has some limitations, mainly false negatives due to low levels of plasma circulating tumor deoxyribonucleic acid and false positives caused by clonal hematopoiesis. Nevertheless, no guidelines and recommendations fully address these issues. Here, an expert panel committee involving representatives from 12 Designated Core Hospitals for Cancer Genomic Medicine in Japan was organized to develop expert consensus recommendations for the use of circulating tumor deoxyribonucleic acid‐based comprehensive genomic profiling. The aim was to generate guidelines for clinicians and allied healthcare professionals on the optimal use of the circulating tumor DNA assays in advanced solid tumors and to aid the design of future clinical trials that utilize and develop circulating tumor DNA assays to refine precision oncology. Fourteen clinical questions regarding circulating tumor deoxyribonucleic acid comprehensive genomic profiling including the timing of testing and considerations for interpreting results were established by searching and curating associated literatures, and corresponding recommendations were prepared based on the literature for each clinical question. Final consensus recommendations were developed by voting to determine the level of each recommendation by the Committee members.

Pathological criteria for multiplex gene-panel testing using next-generation sequencing in non-small cell lung cancer

BACKGROUND

Multiplex gene-panel tests have recently been developed, including the Oncomine Dx Target Test multi-CDx system (ODxTT), and are commonly used to determine the adaptation of molecular-targeting drugs in non-small cell lung cancer. However, in actual clinical settings, we obtain false results owing to the small biopsy samples. We aimed to optimize tissue preparation methods to improve the success rate.

PATIENTS AND METHODS

We investigated 88 biopsy samples. The area and nucleated cell count in the first cut section were quantified using a morphometric software. Pathological parameters, including "total tissue area" and "total nucleated cell count," were calculated by multiplying the total number of slides submitted to ODxTT. Optimal cutoff values to obtain the best success rate were also determined. Additionally, we morphometrically measured actual tumor cell proportions and attempted to determine the lower limit possible to detect mutations.

RESULTS

Optimal cutoff values for "total nucleated cell count" and "total tissue area" were 132,885 and 32.94 mm², respectively. The actual tumor cell proportions ranged from 4.6 to 97.7%. Even in cases with actual tumor cell proportions of less than 20% (ranging from 4.6 to 19.7%), there was no false negative.

CONCLUSION

Thus, we proposed the pathological criteria for accurate ODxTT. Our result suggested that tumor cell proportions of less than 20% (around 5%) could be applicable for ODxTT. We hope that our results will help pathologists to choose between the multi-plex test (ODxTT) or single-plex test in routine diagnostics.