Integrated Evaluation of TRK Expression in Gastric Adenocarcinoma: Correlation with Immunohistochemistry- and In Situ Hybridization–Based Molecular Classification and Diagnostic Challenges

Integrated Evaluation of TRK Expression in Gastric Adenocarcinoma: Correlation with Immunohistochemistry- and In Situ Hybridization–Based Molecular Classification and Diagnostic Challenges | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Integrated Evaluation of TRK Expression in Gastric Adenocarcinoma: Correlation with Immunohistochemistry- and In Situ Hybridization–Based Molecular Classification and Diagnostic Challenges Medine Özgür Günay, Tuğba Başoğlu Tüysüz, Mehmet Fatih Tekin, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9258096/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 16 You are reading this latest preprint version Abstract Background Identification of neurotrophic tyrosine receptor kinase (NTRK) gene fusions has become clinically important because of the tumor-agnostic effectiveness of TRK inhibitors. In gastric adenocarcinoma (G-ACa), NTRK fusions are known to be exceedingly rare (0–1%), and their clinicopathological associations as well as the performance and reliability of diagnostic approaches remain unclear. Pan-TRK immunohistochemistry (IHC) has been proposed as a screening tool for the detection of NTRK fusions. Methods A total of 240 primary G-ACa cases were classified using an IHC/ISH-based molecular algorithm with EBER-ISH, mismatch repair proteins (MLH1, MSH2, MSH6, PMS2), p53, and E-cadherin expression. All tumors were screened for NTRK fusions using pan-TRK IHC. Break-apart NTRK fluorescence in situ hybridization (FISH) was performed in all pan-TRK–positive cases and in a randomly selected subset of 35 pan-TRK–negative tumors. Associations between NTRK-related findings, molecular subgroups, clinicopathological parameters, and survival outcomes were analyzed. Results 240 G-ACas were classified and the subtypes were as follows: 3.8% of the cases (n = 9) were in Gp1; 12.5% of the cases (n = 30) were in Gp2; 12.5% of the cases (n = 30) were in Gp3; 47.9% of the cases (n = 115) were in Gp4, and the remaining cases with wild type p53 expression represented 23.3% of the cases (n = 56) (Gp5). IHC/ISH-based molecular classification showed significant correlations with patient age, Lauren/WHO histologic type, grade, perineural invasion, lymphocytic stromal response and HER2 IHC results (p < 0.05). TRK expression was detected in 1.3% (3/240) of cases and was uniformly weak and focal. None of these cases demonstrated NTRK1/2/3 fusions on FISH analysis. In contrast, borderline or low-level NTRK split signals (10–22%) were identified in 12 of 35 (34.3%) pan-TRK–negative cases. NTRK FISH positivity showed no statistically significant association with IHC/ISH-based molecular subgroups and clinicopathological features. Conclusions An IHC/ISH-based molecular classification showed clinicopathological correlations, supporting its practical use in G-ACa. However, pan-TRK IHC and FISH demonstrated important limitations as screening tools. Borderline or low-level NTRK FISH positivity without TRK protein expression lacked clear biological or clinical relevance and showed no association with molecular subgroups or clinicopathological features. These findings indicate that NTRK testing in G-ACa should be interpreted cautiously within a comprehensive diagnostic framework to avoid overestimation of clinically actionable alterations. Gastric adenocarcinoma molecular classification NTRK gene fusion Pan-TRK NTRK FISH Figures Figure 1 Figure 2 Figure 3 Figure 4 BACKGROUND Gastric adenocarcinoma (G-ACa) is one of the most common malignancies worldwide and continues to be a leading cause of cancer-related mortality. Despite advances in surgical techniques and systemic therapies, the prognosis of patients with advanced-stage disease remains poor, with a median survival rate of less than 12 months [ 1 , 2 ]. This is largely because of the pronounced biological heterogeneity and the limited availability of clinically actionable molecular targets. A deeper understanding of individual gastric cancer subtypes is essential for optimizing therapeutic strategies and promoting personalized medicine. To reflect the major TCGA [ 3 ] and ACRG [ 4 ] molecular subtypes of gastric adenocarcinoma in routine diagnostic practice, immunohistochemistry (IHC) and in situ hybridization (ISH)-based molecular classification systems have been developed [ 5 – 12 ]. These simplified molecular subgroups have been shown to correlate with distinct clinicopathological features and to reflect underlying tumor biology, thereby facilitating the interpretation of rare and potentially targetable molecular alterations within an appropriate biological context. Among tumor-agnostic, targetable molecular alterations, neurotrophic tyrosine receptor kinase (NTRK) gene fusions have attracted considerable attention following the marked clinical efficacy of TRK inhibitors across multiple tumor types. The NTRK1, NTRK2, and NTRK3 genes encode the TRKA, TRKB, and TRKC receptors, respectively, which play a physiological role in neurotrophin-mediated signaling [ 13 ]. Oncogenic NTRK fusions arise from chromosomal rearrangements in which the 3′ region of an NTRK gene is fused to the 5′ region of a partner gene, resulting in the formation of chimeric proteins with constitutive kinase activation, thereby driving tumorigenesis [ 14 ]. Some studies have examined the diagnostic methodologies for NTRK fusion detection and have proposed practical algorithms [ 15 – 17 ]. Although next-generation sequencing (NGS) methods are considered the gold standard for NTRK fusion detection, their routine implementation is limited by cost and technical requirements. From this perspective, pan-TRK IHC has been proposed as a practical first-line screening approach. In the present study, we reclassified primary G-ACas by using IHC and ISH in accordance with the published studies. NTRK fusions were investigated using pan-TRK IHC and confirmatory fluorescence in situ hybridization (FISH). The primary aim was to evaluate the diagnostic performance and reliability of pan-TRK IHC as a screening tool in G-ACa. By applying FISH to both pan-TRK–positive and selected pan-TRK–negative cases, we assessed the concordance between IHC and FISH results. In addition, by correlating NTRK-related IHC and FISH findings with clinicopathological features and IHC/ISH-based molecular subgroups, we aimed to determine whether these findings exhibit consistent biological or clinical patterns in G-ACa. MATERIALS AND METHODS Patients and Tissue Samples Resection specimens of 380 patients diagnosed primary G-ACa between 2013 and 2018 at Pathology Department of Marmara University Hospital, Istanbul were retrospectively evaluated. The patients’ exclusion criterias were inadequate tumor area/ tissue fixation (n=5) and lack of follow- up data (n=135). This resulted in a total number of 240 patients. The dates of operation, patients’ age and sex, histopathological variables and HER2 status were extracted from original pathology reports. The clinical follow-up data was gathered from oncology specific medical records. The dates of death were obtained through the Death Notification System of the Turkish Ministry of Health (obs.gov.tr). We assessed the following histopathological variables: Borrmann macroscopic type, tumor size and location, histologic type (both Lauren and WHO-2019), grade, pT and pN stage according to the AJCC 8th edition, lymphatic/angio/perineural invasion, desmoplastic and lymphocytic stromal response, peritumoral SPEM (spasmolytic polypeptide-expressing metaplasia) and paneth cell metaplasia. For the tissue microarray (TMA) analysis, hematoxylin and eosin (H/E) stained slides of all cases were reviewed to define diagnostic areas. 4 representative 3-mm-diameter cores per case from formalin- fixed paraffin-embedded tissue blocks with different tumor morphology inserted into TMA blocks. IHC, ISH and Pathologic Evaluation IHC of MLH1 (ES05, monoclonal, mouse, Dako, ready-to-use), MSH2 (FE11, monoclonal, mouse, Dako, ready-to-use), MSH6 (EP49, monoclonal, rabbit, Dako, ready-to-use), PMS2 (EP51, monoclonal, rabbit, Dako, ready-to-use), p53 (DO-7, monoclonal, mouse, Dako, ready-to-use), E-cadherin (NCH-38, monoclonal, mouse, Dako, ready-to-use) and pan-TRK (EPR17341, monoclonal, rabbit, Abcam, 1:500), and EBER (EBV encoded small RNA) ISH (Ventana Medical System, Tucson, AZ, USA) were performed on tissue sections from TMA blocks. HER2 (SP3, monoclonal, rabbit, Thermo ScientificTM, Lab VisionTM,1:100) IHC and ISH were performed on whole tissue sections during routine pathological examination. For immunstaining of all markers, the Ventana Benchmark XT automated stainer (Ventana Medical System, Tucson, AZ, USA) was used. For pan-TRK IHC, the signal was detected with OptiView Universal DAB Detection Kit and for the remaining immunhistochemical markers, the signal was detected with ultraViewTM Universal DAB Detection Kit. Chromogenic probe for EBER was detected with ISH Iview Blue Detection Kit on Ventana Benchmark ISH system. A tumour was classified as dMMR (deficient- mismatch repair) if at least one of 4 DNA MMR proteins (MLH1, MSH2, MSH6, PMS2) showed a complete loss of nuclear expression with positive internal control in smooth muscle cells, lymphocytes and benign epithelium. Otherwise, tumors showing partial loss of nuclear expression or not showing loss of nuclear expression were considered pMMR (proficient- mismatch repair). For p53, cases with strong nuclear staining in ≥70% of tumor cells or completely negative staining (no staining or <5% staining) were considered to have aberrant p53 expression [18-20]. The percentage values of p53 staining were determined by counting a total of 1000 cells in the hotspot area with high expression at 200x magnification. In respect of E-cadherin, tumors with complete loss of membranous staining or markedly reduced membranous staining (>90%) were classified as aberrant E-cadherin expression regardless of the nuclear or cytoplasmic staining [21]. For EBER, identifiable strong nuclear staining was considered positive. NTRK gene fusions were evaluated by applying pan-TRK antibody. As previously suggested, tumors were considered positive if ≥1% of tumor cells stained at any intensity above background in any subcellular localization including membranous, cytoplasmic, perinuclear or nuclear [16, 22]. NTRK FISH analysis was performed on TMA sections for confirmation in cases showing pan-TRK expression using Zytolight SPEC NTRK 1/2/3 Dual Color break-apart Probe. Cases containing "split-apart" signals with red and green colors in at least 50 tumor cells, separated by a distance greater than the size of two hybridization probe signal in > 10-15% of tumor cells, were accepted as fusion positive [17]. In order to create a control group among the Pan-TRK negative cases, 35 cases were randomly selected and NTRK1/2/3 FISH analysis was applied. HER2 IHC and ISH were interpreted according to American Society of Clinical Oncology- College of American Pathologists (ASCO -CAP) guidelines [23]. HER2 IHC score 2 or 3 cases were further analysed with FISH and/or silver- ISH (SISH) to detect HER2 amplification. HER2 SISH was performed using Inform HER2 Dual ISH DNA Probe Cocktail Assay, Ventana, New York, USA on an automatic SISH staining device (Ventana Medical System, Tucson, AZ, USA). For HER2 FISH, Zytolight SPEC ERBB2/CEN17 Dual Color Probe was used. IHC and ISH Based Molecular Classification of G-ACa Considering the published molecular classifications by TCGA and ACRG, 240 cases were divided into 5 groups similar to the taxonomic sequence suggested by the previous studies, respectively as shown in Figure 1: Group 1 (Gp1) EBV positive, Group 2 (Gp2) dMMR, Group 3 (Gp3) E-cadherin aberrant, Group 4 (Gp4) p53-aberrant, Group 5 (Gp5) p53-wild. Statistical Analysis NCSS (Number Cruncher Statistical System) (Kaysville, Utah, USA) program was applied for statistical analysis. Descriptive statistical methods (mean, standard deviation, median, frequency, ratio, minimum, maximum) were used for evaluating the study data. The Kruskal Wallis test was used in the comparison of three or more groups that did not show normal distribution. In comparison of qualitative data, Pearson Chi-Square test and Fisher-Exact test were used. Kaplan Meier analysis and Log Rank test were used for survival probabilities. In statistical analysis, significance was considered as p <0.05. Recurrence-free survival (RFS) was calculated from the time period between the date of the operation and the date of first recurrence or the last follow-up date. Overall survival (OS) was defined as the time period between the date of operation and the date of death of any cause or the last follow-up date. RESULTS Clinicopathological Features Patient age ranged from 21 to 90 (median, 65) and most patients were male (70%). Among all of the patients, 10% (25/240) did receive preoperative chemotherapy. Clinical follow-up data was available for all patients with a mean follow up period of 19 months (median 11.5 months). Recurrence (local and/or distant metastasis) was seen in 92 (38%) cases and death occurred in 142 (59%) cases during the follow-up period. Median OS and RFS were 32 and 19 months, respectively. Clinicopathological features of all selected cases are summarized in Table 1. Results of IHC and ISH Based Molecular Classification 240 G-ACas were classified into 5 subtypes based on results of IHC and ISH analysis and the 5 subtypes were as follows: 3.8% of the cases (n=9) were in Gp1; 12.5% of the cases (n=30) were in Gp2; 12.5% of the cases (n=30) were in Gp3; 47.9% of the cases (n=115) were in Gp4, and the remaining cases with wild type p53 expression represented 23.3% of the cases (n=56) (Gp5). Among the subgroups of G-ACa, significant correlation was observed with respect to patient age, Lauren/WHO histologic type, grade, perineural invasion, lymphocytic stromal response and HER2 IHC results as summarized in Table 2 (p<0.05). In all EBV (+) cases, MMR proteins were immunohistochemically intact (mutually exclusive pattern). The patients of Gp2 were significantly characterized by older age (median 71 years). A strong correlation with lymphocytic stromal response and Lauren intestinal type/WHO tubulopapillary type was observed in Gp2 (p<0.05). Perineural invasion in Gp2 was significantly lower compared with other groups (p=0.001). In Gp2, the loss of MLH1 and PMS2 was the predominant pattern (86.2%). Lauren diffuse type/WHO poorly cohesive type was detected to be significantly more prevalent in Gp3 (41%) (p0.05). Results of IHC and FISH Analysis Used to Detect NTRK Gene Fusions and Relationship with Groups och Clinicopathological Features For 3 cases, pan-TRK expression was weak in a small number of tumour cells (Figure 2). While one case had a cytoplasmic punctate staining, the other two cases had a nuclear staining. These cases were in Gp4, Gp1, and the in Gp5, respectively. Histologic types were as follows; mixed type carcinoma, medullary carcinoma and tubulopapillary carcinoma, respectively. In the NTRK FISH analysis applied for confirmation, the split ratio in NTRK genes was found to be <5% in all 3 cases. We selected randomly 35 cases with no pan-TRK staining as negative controls for NTRK FISH analysis. The NTRK gene split signals were considered positive in 12 of 35 cases (34%), with split ratios ranging from 10% to 22%. FISH positivity was detected for NTRK1 in 8 cases, for NTRK3 in 3 cases and for combined NTRK1 and NTRK3 in 1 case. NTRK FISH positivity did not show a statistically significant relationship with any of the molecular subgroups (Gp1-5) in the study (Fisher’s exact test, p = 0.936). No statistically significant associations were identified between NTRK FISH positivity and E-cadherin staining status (intact, heterogeneous, or aberrant), p53 mutation status, MSI status, EBER positivity, or HER2 status (all comparisons p > 0.05). There was no statistically meaningful association between NTRK FISH positivity and sex, tumor location, histological type according to the Lauren classification, WHO 2019 histological subtypes, pT stage, pN stage, early versus advanced disease status, lymphatic invasion, angioinvasion, perineural invasion, desmoplasia, or lymphocytic stromal response (all comparisons p > 0.05). In survival analyses, no statistically significant difference in RFS was observed between NTRK FISH–positive and FISH–negative cases (log-rank test, p = 0.739). Similarly, no significant difference in RFS was identified according to NTRK FISH alteration subtype (p = 0.079). With respect to OS, no statistically significant association was found between NTRK FISH positivity and OS (log-rank test, p = 0.416). Likewise, OS did not differ significantly among groups stratified by NTRK FISH alteration subtype (p = 0.486). Clinical features of cases with Pan-TRK expression or NTRK FISH positivity are summarised in Table 3-4. Representative images of positive NTRK1 FISH analysis from two Pan-TRK negative cases (Case ID 11-12 in Table 4) are shown in Figure 3-4. DISCUSSION Given that the molecular subgroups defined by TCGA and ACRG are genomics-based and therefore have limited applicability in routine pathology practice, IHC- and ISH-based algorithms developed in recent years represent a clinically relevant alternative. In our study, the distribution of molecular subgroups and their associations with clinicopathological features were mostly consistent with the current literature. The significantly higher frequency of prominent lymphocytic stromal response, association with older age, and lower perineural invasion in the dMMR group, as well as the increased HER2 positivity in the p53-aberrant group, support previously reported findings [ 3 , 24 , 25 ]. No statistically significant differences in OS or RFS were observed among our molecular subgroups. Because information on postoperative treatment regimens was unavailable, definitive conclusions regarding survival differences cannot be drawn. In addition, the relatively small number of cases in some subgroups may have limited statistical association. Recent studies have shown that TRK inhibitors achieve remarkable clinical responses in tumors harboring NTRK fusions, irrespective of tumor type. Larotrectinib and entrectinib have received FDA approval for the treatment of adult and pediatric patients with solid tumors harboring NTRK gene fusions [ 26 , 27 ]. Therefore, accurate identification of NTRK fusions carries important clinical value, particularly in patients with advanced-stage disease and limited therapeutic options. Despite the therapeutic relevance of TRK inhibitors, NTRK fusions are exceedingly uncommon in G-ACa, with reported frequencies 0–1% [ 22 , 28 – 30 ]. Owing to its technical simplicity, low cost, and rapid turnaround time, pan-TRK IHC has been proposed as a first-line screening approach for NTRK fusions [ 31 – 35 ]. Nevertheless, recent data suggests that this method has notable limitations. The diagnostic performance of pan-TRK IHC varies considerably across institutions, largely depending on the antibody clone used and the staining platform applied, resulting in marked differences in sensitivity and specificity [ 36 ]. The pan-TRK EPR17341 antibody, which has received FDA approval, targets a C-terminal epitope within the tyrosine kinase domain shared by all three TRK proteins [ 37 ]. In most studies, staining of ≥ 1% of tumor cells at any intensity has been regarded as positive; however, a standardized cutoff value or scoring system has not yet been established [ 38 , 39 ]. Reduced sensitivity has been reported particularly for NTRK3 fusions. Solomon et al. demonstrated sensitivities of 96%, 100%, and 79% for NTRK1, NTRK2, and NTRK3 fusions, respectively [ 22 ], while Gatalica et al. reported false-negative pan-TRK staining in 45% of tumors harboring NTRK3 fusions [ 16 ]. Importantly, pan-TRK antibodies are not fusion-specific, and non-fusion NTRK gene alterations—whose predictive significance remains uncertain—may lead to false-positive immunohistochemical results. NTRK gene amplification was evaluated by NGS method in 1250 tumor samples by Lee et al [ 40 ], and NTRK gene amplification was detected in 28 tumors. When the correlation between gene amplification and protein expression was assessed, pan-TRK expression was obtained in 4/27 (15%) of these tumors. Moreover, Karakas et al. emphasized that diffuse and strong pan-TRK staining is more likely to reflect true NTRK fusions, whereas weak and focal staining shows poor correlation with fusion status [ 41 ]. Aya et al. identified an ATP1B–NTRK1 fusion by RNA sequencing in a gastric carcinoma case exhibiting diffuse and moderately positive pan-TRK expression [ 42 ]. Similarly, Dong et al. detected an LMNA–NTRK1 fusion by RNA sequencing in only one out of 1,970 gastric adenocarcinomas, which showed diffuse and strong cytoplasmic pan-TRK staining [ 43 ]. Our results are in agreement with these previously reported observations. In the present study, pan-TRK immunoreactivity was observed in only 1.3% of cases (3/240), all of which demonstrated weak and focal staining confined to a limited number of tumor cells. None of these cases showed evidence of NTRK1/2/3 fusions on confirmatory break-apart FISH analysis. Despite the availability of multiple molecular diagnostic approaches, such as FISH, reverse transcription polymerase chain reaction (RT-PCR) and DNA- or RNA-based NGS, accurate detection of the diverse spectrum of NTRK fusions using even these methods remains challenging and costly, particularly given the rarity of these alterations [ 15 , 41 ]. Although FISH is widely used in clinical practice for gene fusion detection because of its rapid turnaround time and technical accessibility, our study points to important limitations of this method. In our cohort, borderline or low-level NTRK split signals ranging from 10% to 22% were detected by FISH in 12 of 35 randomly selected cases. None of these cases showed TRK expression with Pan-TRK IHC. We therefore considered that these borderline or low-level FISH-positive results might be related to tissue microarray–related factors, technical artifacts, or intratumoral heterogeneity rather than true oncogenic NTRK fusions. These findings are consistent with the literature indicating that borderline or low-percentage NTRK split signals detected by FISH do not always have a clear clinical or biological significance. In this regard, Wu et al. reported that a subset of NTRK FISH–positive cases (3.1%) in papillary thyroid carcinoma cohorts were reclassified as NTRK-negative following validation with NGS methods [ 44 ]. Remarkably, one of these FISH false-positive cases exhibited a very high proportion of FISH-positive cells (up to 97%), but no fusion transcript could be identified at the RNA level, suggesting the presence of non-functional or biologically inactive DNA rearrangements. The remaining cases demonstrated relatively low proportions (24–35%) of abnormal cells by FISH as observed in our study. NGS, especially RNA-based methods, is widely regarded as the gold standard for the detection of NTRK fusions [ 17 , 45 , 46 ]. However, DNA-based NGS may fail to identify fusions because of technical challenges related to intronic region coverage, whereas RNA-based NGS is highly dependent on RNA quality and integrity [ 38 , 41 ]. Some studies have suggested that NTRK fusions detected by NGS but not supported by FISH or IHC may not always represent clinically actionable events [ 43 ]. These observations show the importance of a multilayered validation strategy. Only a limited number of studies have evaluated NTRK fusion–positive carcinomas in conjunction with clinicopathological features. Reported characteristics in such cases include high-grade or poorly differentiated morphology, frequent lymphovascular invasion, lymph node metastasis, and an overall aggressive clinical course [ 47 , 48 ]. Similarly, in our study, all 3 cases showing Pan-TRK positivity were advanced-stage tumors with deep gastric wall invasion (pT3/pT4). Moreover, whether NTRK fusions are associated with a specific histological or molecular subtype in G-ACa has not yet been clarified. In our cohort, cases with pan-TRK expression or NTRK FISH positivity were distributed across different histological patterns and IHC/ISH-based subgroups. No statistically significant associations were observed between NTRK FISH positivity and clinicopathological parameters. However, Pu et al. reported a higher frequency of NTRK gene alterations in gastric carcinomas showing hepatoid or enteroblastic differentiation and AFP production compared with other gastric cancer subtypes [ 49 ]. Importantly, only half of the NTRK alterations represented NTRK fusions, while the remaining cases were attributable to NTRK gene amplification. Consistent with this limited trend, AFP-producing gastric adenocarcinoma morphology was observed in 2 of the 12 NTRK FISH–positive cases (16.7%) in our cohort. Overall, the discordance observed between pan-TRK IHC and NTRK FISH in our study is in line with previous reports and indicates the inherent limitations of these techniques when applied without complementary RNA- eller DNA- based sequencing approaches. Although IHC/ISH-based molecular classification systems provide a practical framework for capturing tumor biology, their contribution to NTRK-targeted screening strategies in G-ACa appears limited. CONCLUSIONS In this study, an IHC/ISH-based surrogate molecular classification was successfully applied to a large cohort of G-ACa and demonstrated clinicopathological associations consistent with previously reported data, supporting its utility as a practical approach in routine pathology practice. Our findings highlight important limitations of pan-TRK IHC and FISH when applied as screening tools in G-ACa. Borderline or low-level NTRK FISH positivity in the absence of TRK protein expression appears to lack clear biological or clinical significance and showed no meaningful association with clinicopathological features or IHC/ISH-based molecular subgroups. Although NGS is regarded as the reference standard for NTRK fusion detection, its absence in this study reflects real-world diagnostic constraints. These findings emphasize that NTRK testing in G-ACa should be interpreted cautiously and within a comprehensive diagnostic framework to avoid overestimation of clinically actionable alterations. Abbreviations ACRG Asian cancer research group FISH Fluorescence in situ hybridization G-ACa Gastric adenocarcinoma H/E hematoxylin and eosin IHC Immunohistochemistry NCSS Number Cruncher Statistical System NGS Next-generation sequencing NTRK Neurotrophic tyrosine receptor kinase OS Overall survival RFS Recurrence-free survival SPEM Spasmolytic polypeptide-expressing metaplasia TCGA The cancer genome atlas TMA Tissue microarray Declarations Ethics approval and consent to participate Appropriate ethical approval was obtained from the Ethical Board of Marmara University Medical School, Istanbul, Turkey (Protocol number: 09.2019.196). All procedures involving human participants and/or human samples were conducted in accordance with the ethical standards of the institutional and/or national research committee and with the Declaration of Helsinki and its later amendments. The Ethics Committee of Marmara University Medical School granted permission to study archived tissue samples without requiring individual informed consent. Consent for publication Not applicable. Availability of data and materials The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request. Competing interests The authors have no relevant financial or non-financial interests to disclose. Funding This study was funded by the Scientific Research and Projects Board of the Marmara University, Istanbul, Turkey (Grant number: SAG-C-TUP-250919-0287). The funders had no role in the design of the study; data collection and analysis, the decision to publish, or in producing the manuscript. Authors’ contributions All authors contributed to the study conception and design.Material preparation, data collection and analysis were performed and first draft of the manuscript was written by Medine Ozgur Gunay. All authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. The role of the each author in this papper as follows: Conceptualization: Medine Ozgur Gunay, Cigdem Ataizi Celikel Methodology: Medine Ozgur Gunay, Mehmet Fatih Tekin Formal analysis and investigation: Medine Ozgur Gunay, Mehmet Fatih Tekin Data collection- histopathological and immunohistochemical: Medine Ozgur Gunay Data collection- clinical: Tugba Basoglu Tuylu Writing- original draft preparation: Medine Ozgur Gunay Writing- review and editing: Cigdem Ataizi Celikel Funding acquisition: Medine Ozgur Gunay, Cigdem Ataizi Celikel Resources: Medine Ozgur Gunay, Cigdem Ataizi Celikel Supervision: Cigdem Ataizi Celikel Acknowledgements The authors thank Ms. Elif Ugurlu and Ms. Banu Buyukturgay for technical support during sectioning and performing immunohistochemistry. References Bray F, Ferlay J, Soerjomataram I, Siegel RL, Torre LA, Jemal A. 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Microsatellite instability in gastric cancer: molecular bases, clinical perspectives, and new treatment approaches. Cell Mol Life Sci 2018, 75(22):4151-4162. Zhang Q, Wang L, Ni S, Tan C, Cai X, Huang D, et al. Clinicopathological features and prognostic value of mismatch repair protein deficiency in gastric cancer. Int J Clin Exp Pathol 2018, 11(5):2579-2587. Cocco E, Scaltriti M, Drilon A. NTRK fusion-positive cancers and TRK inhibitor therapy. Nat Rev Clin Oncol 2018, 15(12):731-747. Laetsch TW, Hong DS. Tropomyosin Receptor Kinase Inhibitors for the Treatment of TRK Fusion Cancer. Clin Cancer Res 2021, 27(18):4974-4982. Momma T, Saito M, Nakajima S, Saito K, Machida E, Miyabe K, et al. Evaluation of NTRK Fusions Detection Method in Esophageal Squamous Cell Carcinoma and Gastric Adenocarcinoma. International Journal of Molecular Sciences 2026, 27(1):336. Okamura R, Boichard A, Kato S, Sicklick JK, Bazhenova L, Kurzrock R. Analysis of NTRK Alterations in Pan-Cancer Adult and Pediatric Malignancies: Implications for NTRK-Targeted Therapeutics. JCO Precis Oncol 2018, 2018. Zehir A, Benayed R, Shah RH, Syed A, Middha S, Kim HR, et al. Mutational landscape of metastatic cancer revealed from prospective clinical sequencing of 10,000 patients. Nat Med 2017, 23(6):703-713. Xu C, Si L, Wang W, Li Z, Song Z, Wang Q, et al. Expert consensus on the diagnosis and treatment of NTRK gene fusion solid tumors in China. Thorac Cancer 2022, 13(21):3084-3097. De Winne K, Sorber L, Lambin S, Siozopoulou V, Beniuga G, Dedeurwaerdere F, et al. Immunohistochemistry as a screening tool for NTRK gene fusions: results of a first Belgian ring trial. Virchows Arch 2021, 478(2):283-291. Hondelink LM, Schrader AMR, Asri Aghmuni G, Solleveld-Westerink N, Cleton-Jansen AM, van Egmond D, et al. The sensitivity of pan-TRK immunohistochemistry in solid tumours: A meta-analysis. Eur J Cancer 2022, 173:229-237. Brčić I, Godschachner TM, Bergovec M, Igrec J, Till H, Lackner H, et al. Broadening the spectrum of NTRK rearranged mesenchymal tumors and usefulness of pan-TRK immunohistochemistry for identification of NTRK fusions. Mod Pathol 2021, 34(2):396-407. Koopman B, Kuijpers CCHJ, Groen HJM, Timens W, Schuuring E, Willems SM, et al. Detection of NTRK Fusions and TRK Expression and Performance of pan-TRK Immunohistochemistry in Routine Diagnostics: Results from a Nationwide Community-Based Cohort. Diagnostics 2022, 12(3):668. Adam J, Stang NL, Uguen A, Badoual C, Chenard MP, Lantuéjoul S, et al. Multicenter Harmonization Study of Pan-Trk Immunohistochemistry for the Detection of NTRK3 Fusions. Mod Pathol 2023, 36(8):100192. Haberecker M, Töpfer A, Melega F, Moch H, Pauli C. A systematic comparison of pan-Trk immunohistochemistry assays among multiple cancer types. Histopathology 2023, 82(7):1003-1012. Hechtman JF, Benayed R, Hyman DM, Drilon A, Zehir A, Frosina D, et al. Pan-Trk Immunohistochemistry Is an Efficient and Reliable Screen for the Detection of NTRK Fusions. Am J Surg Pathol 2017, 41(11):1547-1551. Bourhis A, Caumont C, Quintin-Roué I, Magro E, Dissaux G, Remoué A, et al. Detection of NTRK fusions in glioblastoma: fluorescent in situ hybridisation is more useful than pan-TRK immunohistochemistry as a screening tool prior to RNA sequencing. Pathology 2022, 54(1):55-62. Lee SJ, Kim NKD, Lee S-H, Kim ST, Park SH, Park JO, et al. NTRK gene amplification in patients with metastatic cancer. Precis Future Med 2017, 1(3):129-137. Karakas C, Giampoli EJ, Love T, Hicks DG, Velez MJ. Validation and interpretation of Pan-TRK immunohistochemistry: a practical approach and challenges with interpretation. Diagn Pathol 2024, 19(1):10. Shinozaki-Ushiku A, Ishikawa S, Komura D, Seto Y, Aburatani H, Ushiku T. The first case of gastric carcinoma with NTRK rearrangement: identification of a novel ATP1B-NTRK1 fusion. Gastric Cancer 2020, 23(5):944-947. Dong K, Yin L, Wang Y, Jia L, Diao X, Huang X, et al. Prevalence and detection methodology for preliminary exploration of NTRK fusion in gastric cancer from a single-center retrospective cohort. Hum Pathol 2024, 148:87-92. Wu S, Liu Y, Li K, Liang Z, Zeng X. Molecular and Cytogenetic Features of NTRK Fusions Enriched in BRAF and RET Double-Negative Papillary Thyroid Cancer. J Mol Diagn 2023, 25(8):569-582. Conde E, Hernandez S, Sanchez E, Regojo RM, Camacho C, Alonso M, et al. Pan-TRK Immunohistochemistry: An Example-Based Practical Approach to Efficiently Identify Patients With NTRK Fusion Cancer. Arch Pathol Lab Med 2021, 145(8):1031-1040. Penault-Llorca F, Rudzinski ER, Sepulveda AR. Testing algorithm for identification of patients with TRK fusion cancer. J Clin Pathol 2019, 72(7):460-467. Farago AF, Taylor MS, Doebele RC, Zhu VW, Kummar S, Spira AI, et al. Clinicopathologic Features of Non-Small-Cell Lung Cancer Harboring an NTRK Gene Fusion. JCO Precis Oncol 2018, 2018. Lasota J, Chłopek M, Lamoureux J, Christiansen J, Kowalik A, Wasąg B, et al. Colonic Adenocarcinomas Harboring NTRK Fusion Genes: A Clinicopathologic and Molecular Genetic Study of 16 Cases and Review of the Literature. Am J Surg Pathol 2020, 44(2):162-173. Pu X, Fu Y, Sun Q, Li L, Kwasi A, Ma Z, et al. NTRK gene alterations were enriched in hepatoid or enteroblastic differentiation type of gastric cancer. J Clin Pathol 2024, 77(9):608-613. Tables Table 1. Clinicopathological features Frequency n % Tumor size 5 cm 130 54,16 Macroscopic type Type 1 17 7,09 Type 2 40 16,67 Type 3 154 64,16 Type 4 29 12,08 Tumor location Antrum 107 44,6 Cardia 50 20,8 Corpus/ fundus 83 34,6 Lauren histologic type Diffuse 31 12,9 Intestinal 116 48,3 Mixed 84 35,0 Undefined* 9 3,8 WHO-19 histologic type Mucinous 16 6,67 Poorly cohesive 31 12,91 Tubular/papillary 100 41,67 Mixed 84 35 Others* 9 3,75 Grade Low grade High grade 79 153 32,92 63,76 Ungraded** 8 3,32 pT stage T1 T2 13 18 5,42 7,5 T3 T4 88 121 36,67 50,41 pN stage N0 50 20,83 N1 38 15,83 N2 62 25,83 N3 90 37,51 Lymphatic invasion Negative 29 12,1 Positive 211 87,9 Angioinvasion Negative 102 42,5 Positive 138 57,5 Perineural invasion Negative 63 26,2 Positive 177 73,8 Desmoplastic response Negative 59 24,6 Positive 181 75,4 Lymphocytic response Negative 83 34,6 Positive 157 65,4 Peritumoral SPEM (n=173) Negative 150 86,7 Positive 23 13,3 Peritumoral paneth cell metaplasia (n=173) Negative 90 52,0 Positive 83 48,0 Death No 98 40,8 Yes 142 59,2 Recurrence No 148 61,7 Yes 92 38,3 HER2- IHC Score 0 131 54,58 Score 1 Score 2 Score 3 10 48 51 4,17 20 21,25 HER2- FISH/SISH Amplification negative 36 36,36 Amplification positive N/A*** 35 28 35,36 28,28 *: medullary carcinoma (8 case) and yolk sac tumour like carcinoma (1 case); **: medullary carcinoma (8 case); ***: cases with HER2 IHC score 2 + / 3 +, in which FISH / SISH not performed. Table 2. Evaluation of clinicopathologic features according to molecular subgroups EBV (+) (n=9) dMMR (n=30) E-cadherin Aberrant (n=30) P53 Aberrant (n=115) P53 Wild (n=56) p n (%) n (%) n (%) n (%) n (%) Age (year) Years (Median) 52-81 (67) 34-87 (71) 29-76 (59) 21-90 (65) 33-85 (63,5) 0,022 Lauren histologic type Diffuse 1 (11,1) 4 (13,3) 12 (40,0) 4 (3,5) 10 (17,9) 0,001 Intestinal 1 (11,1) 19 (63,3) 6 (20,0) 72 (62,6) 18 (32,1) Mixed 5 (55,6) 4 (13,3) 11 (36,7) 36 (31,3) 28 (50,0) Undefined 2 (22,2) 3 (10,0) 1 (3,3) 3 (2,6) 0 (0) WHO- 19 histologic type Mucinous 0 (0) 1 (3,3) 4 (13,3) 9 (7,8) 2 (3,6) 0,001 Poorly cohesive 1 (11,1) 4 (13,3) 12 (40,0) 4 (3,5) 10 (17,9) Tubular/ Papillary 1 (11,1) 18 (60,0) 2 (6,6) 63 (54,8) 16 (28,6) Mixed 5 (55,6) 4 (13,3) 11 (36,6) 36 (31,3) 28 (50) Others 2 (22,2) 3 (10,0) 1 (3,3) 3 (2,6) 0 (0) Grade Low grade 0 (0) 13 (43,3) 3 (10,0) 45 (39,1) 18 (32,1) 0,001 High grade 7 (77,8) 14 (46,6) 27 (90,0) 67 (58,3) 38 (67,9) Ungraded 2 (22,2) 3 (10,0) 0 (0) 3 (2,6) 0 (0) Perineural invasion Negative 1 (11,1) 17 (56,7) 8 (26,6) 30 (26,1) 7 (12,5) 0,001 Positive 8 (88,9) 13 (43,3) 22 (73,4) 85 (73,9) 49 (87,5) Lymphocytic response Negative 2 (22,2) 5 (16,6) 16 (53,4) 30 (26,1) 30 (53,6) 0,001 Positive 7 (77,8) 25 (83,4) 14 (46,6) 85 (73,9) 26 (46,4) HER2 IHC Score 0 7 (77,8) 15 (50,0) 22 (73,3) 50 (43,5) 37 (66,1) 0,018 Score 1 0 (0) 1 (3,3) 1 (3,3) 5 (4,3) 3 (5,4) Score 2 0 (0) 10 (33,3) 5 (16,6) 25 (21,7) 8 (14,3) Score 3 2 (22,2) 4 (13,3) 2 (6,6) 35 (30,4) 8 (14,3) Tablo 3 Clinical features of three cases with Pan-TRK expression Case ID Sex Location Size (cm) Lauren TNM Molecular group pan-TRK 1 M Corpus 8 Mixed T4aN3b Gp4 Cytoplasmic punctate 2 M Antrum 13 Other (medullary type) T4aN3 Gp1 Nuclear 3 M Antrum 10 Intestinal T3N1 Gp5 Nuclear Tablo 4 Clinical features of 12 cases with NTRK1/2/3 FISH Positivity Case ID Sex Location Size (cm) Lauren TNM Molecular group NTRK split rate 1 F Antrum 5 Mixed (+ AFP production) T4aN3a Gp4 NTRK1 12% 2 M Antrum 7 Mixed T4aN3a Gp5 NTRK1 21% 3 F Corpus 8 Intestinal T4aN3a Gp4 NTRK1 10% 4 M Antrum 6 Mixed T3N3a Gp5 NTRK1 18% 5 M Antrum 8.5 Mixed T3N3a Gp4 NTRK3 17% 6 M Antrum 5 Mixed T4aN3a Gp5 NTRK3 14% 7 F Cardia 6 Intestinal (+ AFP production) T3N0 Gp4 NTRK1 22%, NTRK3 18% 8 M Cardia 6.5 Mixed T4aN3b Gp1 NTRK3 12% 9 F Corpus 9 Mixed T4aN3b Gp4 NTRK1 21% 10 M Corpus 8 Intestinal T3N1a Gp4 NTRK1 16% 11 M Cardia 5.5 Intestinal T3N1 Gp2 NTRK1 14% 12 M Antrum 11.5 Diffus T4aN2 Gp3 NTRK1 10% Additional Declarations No competing interests reported. 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Günay","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA8ElEQVRIiWNgGAWjYFCCBCT2ByBmYydFC+MMkBZmUrQw84BJAhp025MPf/zads9uw+3mZ9I2v7bJ8zEzMH74mINbi9mZZwnGsm3FyRvuHDOTzu27bdjGzMAsOXMbHi03cgySJdsSkg1uJAC19NxmBGphY+YloOUwREv6N2nLntv2xGgxbPzYlmBncCPHTJrhx+1EwlrOPEtmZjiXkCB5I6fYsrfhdnIbM2Mzfr8cB4bYj7IEe74b6Rtv/Phz23Z+e/PBDx/xaAEBUHQkNjAwsEgwtoH4jA341YOU/GBgsAdp/cDwh6DiUTAKRsEoGIEAAO9qVYePk7pPAAAAAElFTkSuQmCC","orcid":"","institution":"Marmara Üniversitesi Eğitim ve Araştırma Hastanesi","correspondingAuthor":true,"prefix":"","firstName":"Medine","middleName":"Özgür","lastName":"Günay","suffix":""},{"id":634240087,"identity":"8cac2c93-a2e3-4a41-a6c5-1aa6e48224ab","order_by":1,"name":"Tuğba Başoğlu Tüysüz","email":"","orcid":"","institution":"Marmara Üniversitesi Eğitim ve Araştırma Hastanesi","correspondingAuthor":false,"prefix":"","firstName":"Tuğba","middleName":"Başoğlu","lastName":"Tüysüz","suffix":""},{"id":634240089,"identity":"0c1587b9-3664-4652-a587-c97871d437f9","order_by":2,"name":"Mehmet Fatih Tekin","email":"","orcid":"","institution":"Marmara Üniversitesi Eğitim ve Araştırma Hastanesi","correspondingAuthor":false,"prefix":"","firstName":"Mehmet","middleName":"Fatih","lastName":"Tekin","suffix":""},{"id":634240090,"identity":"0d9af54d-3895-49fa-8475-f71483599da7","order_by":3,"name":"Çiğdem Ataizi Çelikel","email":"","orcid":"","institution":"Marmara Üniversitesi Eğitim ve Araştırma Hastanesi","correspondingAuthor":false,"prefix":"","firstName":"Çiğdem","middleName":"Ataizi","lastName":"Çelikel","suffix":""}],"badges":[],"createdAt":"2026-03-29 10:38:27","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9258096/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9258096/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":108956986,"identity":"38ea060a-745d-4dc3-a0f2-3f2a4a1cb31e","added_by":"auto","created_at":"2026-05-11 08:16:07","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":58825,"visible":true,"origin":"","legend":"\u003cp\u003eIHC and ISH based classification of G-ACa\u003c/p\u003e","description":"","filename":"Binder11.png","url":"https://assets-eu.researchsquare.com/files/rs-9258096/v1/dfa7247f8f54fffd58fa7c6b.png"},{"id":108956989,"identity":"071ae134-ed96-4d93-b9a9-0871570d4998","added_by":"auto","created_at":"2026-05-11 08:16:08","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":4981634,"visible":true,"origin":"","legend":"\u003cp\u003eMixed carcinoma (\u003cstrong\u003ea\u003c/strong\u003e) with cytoplasmic punctate expression with Pan-TRK (\u003cstrong\u003eb\u003c/strong\u003e), medullary carcinoma (\u003cstrong\u003ec\u003c/strong\u003e) with nuclear expression with Pan-TRK (\u003cstrong\u003ed\u003c/strong\u003e), tubular carcinoma (\u003cstrong\u003ee\u003c/strong\u003e) with nuclear expression with Pan-TRK (\u003cstrong\u003ef\u003c/strong\u003e) (H/Ex20) (IHCx40)\u003c/p\u003e","description":"","filename":"Binder12.png","url":"https://assets-eu.researchsquare.com/files/rs-9258096/v1/05707a16bc5e328501cd4109.png"},{"id":108956990,"identity":"2ec4eec6-42c5-4585-8fb0-5cd4432c6928","added_by":"auto","created_at":"2026-05-11 08:16:08","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1395049,"visible":true,"origin":"","legend":"\u003cp\u003eNTRK1 FISH analysis in a pan-TRK–negative tumor (case ID 11 in Table 4) classified within the dMMR group, demonstrated a split signal in 14% of tumor cells.\u003c/p\u003e","description":"","filename":"Binder13.png","url":"https://assets-eu.researchsquare.com/files/rs-9258096/v1/cf59dfcf296c6caaa636decb.png"},{"id":108956866,"identity":"357d793f-2fd5-4211-9d54-99e5a730622f","added_by":"auto","created_at":"2026-05-11 08:15:29","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":1153053,"visible":true,"origin":"","legend":"\u003cp\u003eNTRK1 FISH analysis in a pan-TRK–negative tumor (case ID 12 in Table 4) classified within the E-kaderin aberrant group, demonstrated a split signal in 10% of tumor cells.\u003c/p\u003e","description":"","filename":"Binder14.png","url":"https://assets-eu.researchsquare.com/files/rs-9258096/v1/a896db18e5c517327be3627b.png"},{"id":108957165,"identity":"961d0884-393a-47fd-bbca-4ea0920338e7","added_by":"auto","created_at":"2026-05-11 08:17:02","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":8485151,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9258096/v1/841fc290-431c-4994-b0ca-a8c75d7948a7.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Integrated Evaluation of TRK Expression in Gastric Adenocarcinoma: Correlation with Immunohistochemistry- and In Situ Hybridization–Based Molecular Classification and Diagnostic Challenges","fulltext":[{"header":"BACKGROUND","content":"\u003cp\u003eGastric adenocarcinoma (G-ACa) is one of the most common malignancies worldwide and continues to be a leading cause of cancer-related mortality. Despite advances in surgical techniques and systemic therapies, the prognosis of patients with advanced-stage disease remains poor, with a median survival rate of less than 12 months [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. This is largely because of the pronounced biological heterogeneity and the limited availability of clinically actionable molecular targets. A deeper understanding of individual gastric cancer subtypes is essential for optimizing therapeutic strategies and promoting personalized medicine.\u003c/p\u003e \u003cp\u003eTo reflect the major TCGA [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e] and ACRG [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e] molecular subtypes of gastric adenocarcinoma in routine diagnostic practice, immunohistochemistry (IHC) and in situ hybridization (ISH)-based molecular classification systems have been developed [\u003cspan additionalcitationids=\"CR6 CR7 CR8 CR9 CR10 CR11\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. These simplified molecular subgroups have been shown to correlate with distinct clinicopathological features and to reflect underlying tumor biology, thereby facilitating the interpretation of rare and potentially targetable molecular alterations within an appropriate biological context.\u003c/p\u003e \u003cp\u003eAmong tumor-agnostic, targetable molecular alterations, neurotrophic tyrosine receptor kinase (NTRK) gene fusions have attracted considerable attention following the marked clinical efficacy of TRK inhibitors across multiple tumor types. The NTRK1, NTRK2, and NTRK3 genes encode the TRKA, TRKB, and TRKC receptors, respectively, which play a physiological role in neurotrophin-mediated signaling [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Oncogenic NTRK fusions arise from chromosomal rearrangements in which the 3\u0026prime; region of an NTRK gene is fused to the 5\u0026prime; region of a partner gene, resulting in the formation of chimeric proteins with constitutive kinase activation, thereby driving tumorigenesis [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eSome studies have examined the diagnostic methodologies for NTRK fusion detection and have proposed practical algorithms [\u003cspan additionalcitationids=\"CR16\" citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Although next-generation sequencing (NGS) methods are considered the gold standard for NTRK fusion detection, their routine implementation is limited by cost and technical requirements. From this perspective, pan-TRK IHC has been proposed as a practical first-line screening approach.\u003c/p\u003e \u003cp\u003eIn the present study, we reclassified primary G-ACas by using IHC and ISH in accordance with the published studies. NTRK fusions were investigated using pan-TRK IHC and confirmatory fluorescence in situ hybridization (FISH). The primary aim was to evaluate the diagnostic performance and reliability of pan-TRK IHC as a screening tool in G-ACa. By applying FISH to both pan-TRK\u0026ndash;positive and selected pan-TRK\u0026ndash;negative cases, we assessed the concordance between IHC and FISH results. In addition, by correlating NTRK-related IHC and FISH findings with clinicopathological features and IHC/ISH-based molecular subgroups, we aimed to determine whether these findings exhibit consistent biological or clinical patterns in G-ACa.\u003c/p\u003e"},{"header":"MATERIALS AND METHODS","content":"\u003cp\u003e\u003cstrong\u003ePatients and Tissue Samples\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eResection specimens of 380 patients diagnosed primary G-ACa between 2013 and 2018 at Pathology Department of Marmara University Hospital, Istanbul were retrospectively evaluated. The patients\u0026rsquo; exclusion criterias were inadequate tumor area/ tissue fixation (n=5) and lack of follow- up data (n=135). This resulted in a total number of 240 patients. The dates of operation, patients\u0026rsquo; age and sex, histopathological variables and HER2 status were extracted from original pathology reports. The clinical follow-up data was gathered from oncology specific medical records. The dates of death were obtained through the Death Notification System of the Turkish Ministry of Health (obs.gov.tr). We assessed the following histopathological variables: Borrmann macroscopic type, tumor size and location, histologic type (both Lauren and WHO-2019), grade, pT and pN stage according to the AJCC 8th edition, lymphatic/angio/perineural invasion, desmoplastic and lymphocytic stromal response, peritumoral SPEM (spasmolytic polypeptide-expressing metaplasia) and paneth cell metaplasia.\u003c/p\u003e\n\u003cp\u003eFor the tissue microarray (TMA) analysis, hematoxylin and eosin (H/E) stained slides of all cases were reviewed to define diagnostic areas. 4 representative 3-mm-diameter cores per case from formalin- fixed paraffin-embedded tissue blocks with different tumor morphology inserted into TMA blocks.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eIHC, ISH and Pathologic Evaluation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIHC of MLH1 (ES05, monoclonal, mouse, Dako, ready-to-use), MSH2 (FE11, monoclonal, mouse, Dako, ready-to-use), MSH6 (EP49, monoclonal, rabbit, Dako, ready-to-use), PMS2 (EP51, monoclonal, rabbit, Dako, ready-to-use), p53 (DO-7, monoclonal, mouse, Dako, ready-to-use), E-cadherin (NCH-38, monoclonal, mouse, Dako, ready-to-use) and pan-TRK (EPR17341, monoclonal, rabbit, Abcam, 1:500), and EBER (EBV encoded small RNA) ISH (Ventana Medical System, Tucson, AZ, USA) \u0026nbsp; were performed on tissue sections from TMA blocks. HER2 (SP3, monoclonal, rabbit, Thermo ScientificTM, Lab VisionTM,1:100) IHC and ISH were performed on whole tissue sections during routine pathological examination. For immunstaining of all markers, the Ventana Benchmark XT automated stainer (Ventana Medical System, Tucson, AZ, USA) was used. For pan-TRK IHC, the signal was detected with OptiView Universal DAB Detection Kit and for the remaining immunhistochemical markers, the signal was detected with ultraViewTM Universal DAB Detection Kit. Chromogenic probe for EBER was detected with ISH Iview Blue Detection Kit on Ventana Benchmark ISH system. \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eA tumour was classified as dMMR (deficient- mismatch repair) if at least one of 4 DNA MMR proteins (MLH1, MSH2, MSH6, PMS2) showed a complete loss of nuclear expression with positive internal control in smooth muscle cells, lymphocytes and benign epithelium. Otherwise, tumors showing partial loss of nuclear expression or not showing loss of nuclear expression were considered pMMR (proficient- mismatch repair). For p53, cases with strong nuclear staining in \u0026ge;70% of tumor cells or completely negative staining (no staining or \u0026lt;5% staining) were considered to have aberrant p53 expression [18-20]. The percentage values of p53 staining were determined by counting a total of 1000 cells in the hotspot area with high expression at 200x magnification. In respect of E-cadherin, tumors with complete loss of membranous staining or markedly reduced membranous staining (\u0026gt;90%) were classified as aberrant E-cadherin expression regardless of the nuclear or cytoplasmic staining [21]. For EBER, identifiable strong nuclear staining was considered positive.\u003c/p\u003e\n\u003cp\u003eNTRK gene fusions were evaluated by applying pan-TRK antibody. As previously suggested, tumors were considered positive if \u0026ge;1% of tumor cells stained at any intensity above background in any subcellular localization including membranous, cytoplasmic, perinuclear or nuclear [16, 22]. NTRK FISH analysis was performed on TMA sections for confirmation in cases showing pan-TRK expression using Zytolight SPEC NTRK 1/2/3 Dual Color break-apart Probe. Cases containing \u0026quot;split-apart\u0026quot; signals with red and green colors in at least 50 tumor cells, separated by a distance greater than the size of two hybridization probe signal in \u0026gt; 10-15% of tumor cells, were accepted as fusion positive [17]. In order to create a control group among the Pan-TRK negative cases, 35 cases were randomly selected and NTRK1/2/3 FISH analysis was applied.\u003c/p\u003e\n\u003cp\u003eHER2 IHC and ISH were interpreted according to American Society of Clinical Oncology- College of American Pathologists (ASCO -CAP) guidelines [23]. HER2 IHC score 2 or 3 cases were further analysed with FISH and/or silver- ISH (SISH) to detect HER2 amplification. HER2 SISH was performed using Inform HER2 Dual ISH DNA Probe Cocktail Assay, Ventana, New York, USA on an automatic SISH staining device (Ventana Medical System, Tucson, AZ, USA). For HER2 FISH, Zytolight SPEC ERBB2/CEN17 Dual Color Probe was used.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eIHC and ISH Based Molecular Classification of G-ACa\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eConsidering the published molecular classifications by TCGA and ACRG, 240 cases were divided into 5 groups similar to the taxonomic sequence suggested by the previous studies, respectively as shown in Figure 1: Group 1 (Gp1) EBV positive, Group 2 (Gp2) dMMR, Group 3 (Gp3) E-cadherin aberrant, Group 4 (Gp4) p53-aberrant, Group 5 (Gp5) p53-wild.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical Analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNCSS (Number Cruncher Statistical System) (Kaysville, Utah, USA) program was applied for statistical analysis. Descriptive statistical methods (mean, standard deviation, median, frequency, ratio, minimum, maximum) were used for evaluating the study data. The Kruskal Wallis test was used in the comparison of three or more groups that did not show normal distribution. In comparison of qualitative data, Pearson Chi-Square test and Fisher-Exact test were used. Kaplan Meier analysis and Log Rank test were used for survival probabilities. In statistical analysis, significance was considered as p \u0026lt;0.05.\u003c/p\u003e\n\u003cp\u003eRecurrence-free survival (RFS) was calculated from the time period between the date of the operation and the date of first recurrence or the last follow-up date. Overall survival (OS) was defined as the time period between the date of operation and the date of death of any cause or the last follow-up date.\u003c/p\u003e"},{"header":"RESULTS","content":"\u003cp\u003e\u003cstrong\u003eClinicopathological Features\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePatient age ranged from 21 to 90 (median, 65) and most patients were male (70%). Among all of the patients, 10% (25/240) did receive preoperative chemotherapy. Clinical follow-up data was available for all patients with a mean follow up period of 19 months (median 11.5 months). Recurrence (local and/or distant metastasis) was seen in 92 (38%) cases and death occurred in 142 (59%) cases during the follow-up period. Median OS and RFS were 32 and 19 months, respectively. Clinicopathological features of all selected cases are summarized in Table 1.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults of IHC and ISH Based Molecular Classification\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e240 G-ACas were classified into 5 subtypes based on results of IHC and ISH analysis and the 5 subtypes were as follows: 3.8% of the cases (n=9) were in Gp1; 12.5% of the cases (n=30) were in Gp2; 12.5% of the cases (n=30) were in Gp3; 47.9% of the cases (n=115) were in Gp4, and the remaining cases with wild type p53 expression represented 23.3% of the cases (n=56) (Gp5).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAmong the subgroups of G-ACa, significant correlation was observed with respect to patient age, Lauren/WHO histologic type, grade, perineural invasion, lymphocytic stromal response and HER2 IHC results as summarized in Table 2 (p\u0026lt;0.05).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn all EBV (+) cases, MMR proteins were immunohistochemically intact (mutually exclusive pattern). The patients of Gp2 were significantly characterized by older age (median 71 years). A strong correlation with lymphocytic stromal response and Lauren intestinal type/WHO tubulopapillary type was observed in Gp2 (p\u0026lt;0.05). Perineural invasion in Gp2 was significantly lower compared with other groups (p=0.001). In Gp2, the loss of MLH1 and PMS2 was the predominant pattern (86.2%). Lauren diffuse type/WHO poorly cohesive type was detected to be significantly more prevalent in Gp3 (41%) (p\u0026lt;0.05). The HER2 positivity (HER2 IHC score 3) in Gp4 was significantly higher (30%) than the other groups (p=0.018).\u003c/p\u003e\n\u003cp\u003eNo significant difference was found among the subgroups for both OS and RFS (p\u0026gt;0.05).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults of IHC and FISH Analysis Used to Detect NTRK Gene Fusions and Relationship with Groups och Clinicopathological Features\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFor 3 cases, pan-TRK expression was weak in a small number of tumour cells (Figure 2). While \u0026nbsp;one case had a cytoplasmic punctate staining, the other two cases had a nuclear staining. These cases were in Gp4, Gp1, and the in Gp5, respectively. Histologic types were as follows; mixed type carcinoma, medullary carcinoma and tubulopapillary carcinoma, respectively. In the NTRK FISH analysis applied for confirmation, the split ratio in NTRK genes was found to be \u0026lt;5% in all 3 cases.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eWe selected randomly 35 cases with no pan-TRK staining as negative controls for NTRK FISH analysis. The NTRK gene split signals were considered positive in 12 of 35 cases (34%), with split ratios ranging from 10% to 22%. FISH positivity was detected for NTRK1 in 8 cases, for NTRK3 in 3 cases and for combined NTRK1 and NTRK3 in 1 case.\u003c/p\u003e\n\u003cp\u003eNTRK FISH positivity did not show a statistically significant relationship with any of the molecular subgroups (Gp1-5) in the study (Fisher\u0026rsquo;s exact test, p = 0.936). No statistically significant associations were identified between NTRK FISH positivity and E-cadherin staining status (intact, heterogeneous, or aberrant), p53 mutation status, MSI status, EBER positivity, or HER2 status (all comparisons p \u0026gt; 0.05). There was no statistically meaningful association between NTRK FISH positivity and sex, tumor location, histological type according to the Lauren classification, WHO 2019 histological subtypes, pT stage, pN stage, early versus advanced disease status, lymphatic invasion, angioinvasion, perineural invasion, desmoplasia, or lymphocytic stromal response (all comparisons p \u0026gt; 0.05).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn survival analyses, no statistically significant difference in RFS was observed between NTRK FISH\u0026ndash;positive and FISH\u0026ndash;negative cases (log-rank test, p = 0.739). Similarly, no significant difference in RFS was identified according to NTRK FISH alteration subtype (p = 0.079).\u003c/p\u003e\n\u003cp\u003eWith respect to OS, no statistically significant association was found between NTRK FISH positivity and OS (log-rank test, p = 0.416). Likewise, OS did not differ significantly among groups stratified by NTRK FISH alteration subtype (p = 0.486).\u003c/p\u003e\n\u003cp\u003eClinical features of cases with Pan-TRK expression or NTRK FISH positivity are summarised in Table 3-4. Representative images of positive NTRK1 FISH analysis from two Pan-TRK negative cases (Case ID 11-12 in Table 4) are shown in Figure 3-4.\u0026nbsp;\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eGiven that the molecular subgroups defined by TCGA and ACRG are genomics-based and therefore have limited applicability in routine pathology practice, IHC- and ISH-based algorithms developed in recent years represent a clinically relevant alternative. In our study, the distribution of molecular subgroups and their associations with clinicopathological features were mostly consistent with the current literature. The significantly higher frequency of prominent lymphocytic stromal response, association with older age, and lower perineural invasion in the dMMR group, as well as the increased HER2 positivity in the p53-aberrant group, support previously reported findings [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. No statistically significant differences in OS or RFS were observed among our molecular subgroups. Because information on postoperative treatment regimens was unavailable, definitive conclusions regarding survival differences cannot be drawn. In addition, the relatively small number of cases in some subgroups may have limited statistical association.\u003c/p\u003e \u003cp\u003eRecent studies have shown that TRK inhibitors achieve remarkable clinical responses in tumors harboring NTRK fusions, irrespective of tumor type. Larotrectinib and entrectinib have received FDA approval for the treatment of adult and pediatric patients with solid tumors harboring NTRK gene fusions [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Therefore, accurate identification of NTRK fusions carries important clinical value, particularly in patients with advanced-stage disease and limited therapeutic options. Despite the therapeutic relevance of TRK inhibitors, NTRK fusions are exceedingly uncommon in G-ACa, with reported frequencies 0\u0026ndash;1% [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan additionalcitationids=\"CR29\" citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eOwing to its technical simplicity, low cost, and rapid turnaround time, pan-TRK IHC has been proposed as a first-line screening approach for NTRK fusions [\u003cspan additionalcitationids=\"CR32 CR33 CR34\" citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. Nevertheless, recent data suggests that this method has notable limitations. The diagnostic performance of pan-TRK IHC varies considerably across institutions, largely depending on the antibody clone used and the staining platform applied, resulting in marked differences in sensitivity and specificity [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. The pan-TRK EPR17341 antibody, which has received FDA approval, targets a C-terminal epitope within the tyrosine kinase domain shared by all three TRK proteins [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. In most studies, staining of \u0026ge;\u0026thinsp;1% of tumor cells at any intensity has been regarded as positive; however, a standardized cutoff value or scoring system has not yet been established [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e, \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. Reduced sensitivity has been reported particularly for NTRK3 fusions. Solomon et al. demonstrated sensitivities of 96%, 100%, and 79% for NTRK1, NTRK2, and NTRK3 fusions, respectively [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e], while Gatalica et al. reported false-negative pan-TRK staining in 45% of tumors harboring NTRK3 fusions [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Importantly, pan-TRK antibodies are not fusion-specific, and non-fusion NTRK gene alterations\u0026mdash;whose predictive significance remains uncertain\u0026mdash;may lead to false-positive immunohistochemical results. NTRK gene amplification was evaluated by NGS method in 1250 tumor samples by Lee et al [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e], and NTRK gene amplification was detected in 28 tumors. When the correlation between gene amplification and protein expression was assessed, pan-TRK expression was obtained in 4/27 (15%) of these tumors. Moreover, Karakas et al. emphasized that diffuse and strong pan-TRK staining is more likely to reflect true NTRK fusions, whereas weak and focal staining shows poor correlation with fusion status [\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]. Aya et al. identified an ATP1B\u0026ndash;NTRK1 fusion by RNA sequencing in a gastric carcinoma case exhibiting diffuse and moderately positive pan-TRK expression [\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e]. Similarly, Dong et al. detected an LMNA\u0026ndash;NTRK1 fusion by RNA sequencing in only one out of 1,970 gastric adenocarcinomas, which showed diffuse and strong cytoplasmic pan-TRK staining [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e]. Our results are in agreement with these previously reported observations. In the present study, pan-TRK immunoreactivity was observed in only 1.3% of cases (3/240), all of which demonstrated weak and focal staining confined to a limited number of tumor cells. None of these cases showed evidence of NTRK1/2/3 fusions on confirmatory break-apart FISH analysis.\u003c/p\u003e \u003cp\u003eDespite the availability of multiple molecular diagnostic approaches, such as FISH, reverse transcription polymerase chain reaction (RT-PCR) and DNA- or RNA-based NGS, accurate detection of the diverse spectrum of NTRK fusions using even these methods remains challenging and costly, particularly given the rarity of these alterations [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAlthough FISH is widely used in clinical practice for gene fusion detection because of its rapid turnaround time and technical accessibility, our study points to important limitations of this method. In our cohort, borderline or low-level NTRK split signals ranging from 10% to 22% were detected by FISH in 12 of 35 randomly selected cases. None of these cases showed TRK expression with Pan-TRK IHC. We therefore considered that these borderline or low-level FISH-positive results might be related to tissue microarray\u0026ndash;related factors, technical artifacts, or intratumoral heterogeneity rather than true oncogenic NTRK fusions. These findings are consistent with the literature indicating that borderline or low-percentage NTRK split signals detected by FISH do not always have a clear clinical or biological significance. In this regard, Wu et al. reported that a subset of NTRK FISH\u0026ndash;positive cases (3.1%) in papillary thyroid carcinoma cohorts were reclassified as NTRK-negative following validation with NGS methods [\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e]. Remarkably, one of these FISH false-positive cases exhibited a very high proportion of FISH-positive cells (up to 97%), but no fusion transcript could be identified at the RNA level, suggesting the presence of non-functional or biologically inactive DNA rearrangements. The remaining cases demonstrated relatively low proportions (24\u0026ndash;35%) of abnormal cells by FISH as observed in our study.\u003c/p\u003e \u003cp\u003eNGS, especially RNA-based methods, is widely regarded as the gold standard for the detection of NTRK fusions [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e]. However, DNA-based NGS may fail to identify fusions because of technical challenges related to intronic region coverage, whereas RNA-based NGS is highly dependent on RNA quality and integrity [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]. Some studies have suggested that NTRK fusions detected by NGS but not supported by FISH or IHC may not always represent clinically actionable events [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e]. These observations show the importance of a multilayered validation strategy.\u003c/p\u003e \u003cp\u003eOnly a limited number of studies have evaluated NTRK fusion\u0026ndash;positive carcinomas in conjunction with clinicopathological features. Reported characteristics in such cases include high-grade or poorly differentiated morphology, frequent lymphovascular invasion, lymph node metastasis, and an overall aggressive clinical course [\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e, \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e]. Similarly, in our study, all 3 cases showing Pan-TRK positivity were advanced-stage tumors with deep gastric wall invasion (pT3/pT4). Moreover, whether NTRK fusions are associated with a specific histological or molecular subtype in G-ACa has not yet been clarified. In our cohort, cases with pan-TRK expression or NTRK FISH positivity were distributed across different histological patterns and IHC/ISH-based subgroups. No statistically significant associations were observed between NTRK FISH positivity and clinicopathological parameters. However, Pu et al. reported a higher frequency of NTRK gene alterations in gastric carcinomas showing hepatoid or enteroblastic differentiation and AFP production compared with other gastric cancer subtypes [\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e]. Importantly, only half of the NTRK alterations represented NTRK fusions, while the remaining cases were attributable to NTRK gene amplification. Consistent with this limited trend, AFP-producing gastric adenocarcinoma morphology was observed in 2 of the 12 NTRK FISH\u0026ndash;positive cases (16.7%) in our cohort.\u003c/p\u003e \u003cp\u003eOverall, the discordance observed between pan-TRK IHC and NTRK FISH in our study is in line with previous reports and indicates the inherent limitations of these techniques when applied without complementary RNA- eller DNA- based sequencing approaches. Although IHC/ISH-based molecular classification systems provide a practical framework for capturing tumor biology, their contribution to NTRK-targeted screening strategies in G-ACa appears limited.\u003c/p\u003e"},{"header":"CONCLUSIONS","content":"\u003cp\u003eIn this study, an IHC/ISH-based surrogate molecular classification was successfully applied to a large cohort of G-ACa and demonstrated clinicopathological associations consistent with previously reported data, supporting its utility as a practical approach in routine pathology practice.\u003c/p\u003e \u003cp\u003eOur findings highlight important limitations of pan-TRK IHC and FISH when applied as screening tools in G-ACa. Borderline or low-level NTRK FISH positivity in the absence of TRK protein expression appears to lack clear biological or clinical significance and showed no meaningful association with clinicopathological features or IHC/ISH-based molecular subgroups. Although NGS is regarded as the reference standard for NTRK fusion detection, its absence in this study reflects real-world diagnostic constraints. These findings emphasize that NTRK testing in G-ACa should be interpreted cautiously and within a comprehensive diagnostic framework to avoid overestimation of clinically actionable alterations.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eACRG Asian cancer research group \u003c/p\u003e\n\u003cp\u003eFISH Fluorescence in situ hybridization\u003c/p\u003e\n\u003cp\u003eG-ACa Gastric adenocarcinoma \u003c/p\u003e\n\u003cp\u003eH/E hematoxylin and eosin \u003c/p\u003e\n\u003cp\u003eIHC Immunohistochemistry \u003c/p\u003e\n\u003cp\u003eNCSS Number Cruncher Statistical System \u003c/p\u003e\n\u003cp\u003eNGS Next-generation sequencing \u003c/p\u003e\n\u003cp\u003eNTRK Neurotrophic tyrosine receptor kinase\u003c/p\u003e\n\u003cp\u003eOS Overall survival\u003c/p\u003e\n\u003cp\u003eRFS Recurrence-free survival \u003c/p\u003e\n\u003cp\u003eSPEM Spasmolytic polypeptide-expressing metaplasia\u003c/p\u003e\n\u003cp\u003eTCGA The cancer genome atlas\u003c/p\u003e\n\u003cp\u003eTMA Tissue microarray\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAppropriate ethical approval was obtained from the Ethical Board of Marmara University Medical School, Istanbul, Turkey (Protocol number: 09.2019.196).\u003c/p\u003e\n\u003cp\u003eAll procedures involving human participants and/or human samples were conducted in accordance with the ethical standards of the institutional and/or national research committee and with the Declaration of Helsinki and its later amendments.\u003c/p\u003e\n\u003cp\u003eThe Ethics Committee of Marmara University Medical School granted permission to study archived tissue samples without requiring individual informed consent.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors have no relevant financial or non-financial interests to disclose.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was funded by the Scientific Research and Projects Board of the Marmara University, Istanbul, Turkey (Grant number: SAG-C-TUP-250919-0287). The funders had no role in the design of the study; data collection and analysis, the decision to publish, or in producing the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors contributed to the study conception and design.Material preparation, data collection and analysis were performed and first draft of the manuscript was written by Medine Ozgur Gunay. All authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. The role of the each author in this papper as follows:\u003c/p\u003e\n\u003cp\u003eConceptualization: Medine Ozgur Gunay, Cigdem Ataizi Celikel\u003c/p\u003e\n\u003cp\u003eMethodology: Medine Ozgur Gunay, Mehmet Fatih Tekin\u003c/p\u003e\n\u003cp\u003eFormal analysis and investigation: Medine Ozgur Gunay, Mehmet Fatih Tekin\u003c/p\u003e\n\u003cp\u003eData collection- histopathological and immunohistochemical: Medine Ozgur Gunay\u003c/p\u003e\n\u003cp\u003eData collection- clinical: Tugba Basoglu Tuylu\u003c/p\u003e\n\u003cp\u003eWriting- original draft preparation: Medine Ozgur Gunay\u003c/p\u003e\n\u003cp\u003eWriting- review and editing: Cigdem Ataizi Celikel\u003c/p\u003e\n\u003cp\u003eFunding acquisition: Medine Ozgur Gunay, Cigdem Ataizi Celikel\u003c/p\u003e\n\u003cp\u003eResources: Medine Ozgur Gunay, Cigdem Ataizi Celikel\u003c/p\u003e\n\u003cp\u003eSupervision: Cigdem Ataizi Celikel\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors thank Ms. Elif Ugurlu and Ms. Banu Buyukturgay for technical support during sectioning and performing immunohistochemistry.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eBray F, Ferlay J, Soerjomataram I, Siegel RL, Torre LA, Jemal A. Global cancer statistics 2018: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. \u003cem\u003eCA Cancer J Clin \u003c/em\u003e2018, 68(6):394-424.\u003c/li\u003e\n\u003cli\u003eMachlowska J, Baj J, Sitarz M, Maciejewski R, Sitarz R. Gastric Cancer: Epidemiology, Risk Factors, Classification, Genomic Characteristics and Treatment Strategies. \u003cem\u003eInt J Mol Sci \u003c/em\u003e2020, 21(11).\u003c/li\u003e\n\u003cli\u003eCancer Genome Atlas Research Network. Comprehensive molecular characterization of gastric adenocarcinoma. \u003cem\u003eNature\u003c/em\u003e. 2014;513:202\u0026ndash;9.\u003c/li\u003e\n\u003cli\u003eCristescu R, Lee J, Nebozhyn M, Kim KM, Ting JC, Wong SS, et al. 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NTRK gene alterations were enriched in hepatoid or enteroblastic differentiation type of gastric cancer. \u003cem\u003eJ Clin Pathol \u003c/em\u003e2024, 77(9):608-613.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003eTable 1.\u0026nbsp;\u003c/strong\u003eClinicopathological features\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 331px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 176px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFrequency\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 331px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e\u003cstrong\u003en\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e%\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"3\" valign=\"top\" style=\"width: 152px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTumor size\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026lt;2 cm\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e2,92\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e2-5 cm\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e103\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e42,92\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026gt;5 cm\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e130\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e54,16\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 152px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMacroscopic type\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eType 1\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e7,09\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;\u003cstrong\u003eType 2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e16,67\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eType 3\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e154\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e64,16\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eType 4\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e12,08\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"3\" valign=\"top\" style=\"width: 152px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTumor location\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAntrum\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e107\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e44,6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCardia\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e20,8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCorpus/ fundus\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e34,6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 152px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLauren\u0026nbsp;histologic type\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eDiffuse\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e12,9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eIntestinal\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e116\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e48,3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMixed\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e84\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e35,0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eUndefined*\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e3,8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"5\" valign=\"top\" style=\"width: 152px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eWHO-19\u0026nbsp;histologic type\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMucinous\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e6,67\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePoorly cohesive\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e12,91\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTubular/papillary\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e41,67\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMixed\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e84\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e35\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eOthers*\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e3,75\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 152px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGrade\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLow\u0026nbsp;grade\u0026nbsp;High grade\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e79\u003c/p\u003e\n \u003cp\u003e153\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e32,92\u003c/p\u003e\n \u003cp\u003e63,76\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eUngraded**\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e3,32\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 152px;\"\u003e\n \u003cp\u003e\u003cstrong\u003epT stage\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eT1\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eT2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003cp\u003e18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e5,42\u003c/p\u003e\n \u003cp\u003e7,5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eT3\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eT4\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e88\u003c/p\u003e\n \u003cp\u003e121\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e36,67\u003c/p\u003e\n \u003cp\u003e50,41\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 152px;\"\u003e\n \u003cp\u003e\u003cstrong\u003epN stage\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eN0\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e20,83\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eN1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e15,83\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eN2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e25,83\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eN3\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e37,51\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 152px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLymphatic invasion\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNegative\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e12,1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePositive\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e211\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e87,9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 152px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAngioinvasion\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNegative\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e102\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e42,5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePositive\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e138\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e57,5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 152px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePerineural invasion\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNegative\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e26,2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePositive\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e177\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e73,8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 152px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eDesmoplastic response\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNegative\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e24,6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePositive\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e181\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e75,4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 152px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLymphocytic\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eresponse\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNegative\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e34,6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePositive\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e157\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e65,4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 152px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePeritumoral SPEM\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=173)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNegative\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e150\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e86,7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePositive\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e13,3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 152px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePeritumoral\u0026nbsp;paneth cell\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003emetaplasia (n=173)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNegative\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e52,0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePositive\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e48,0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 152px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eDeath\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNo\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e40,8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eYes\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e142\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e59,2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 152px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eRecurrence\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNo\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e148\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e61,7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eYes\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e38,3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 152px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHER2- IHC\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eScore 0\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e131\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e54,58\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eScore 1\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eScore 2\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eScore 3\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003cp\u003e48\u003c/p\u003e\n \u003cp\u003e51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e4,17\u003c/p\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003cp\u003e21,25\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 152px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHER2- FISH/SISH\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAmplification negative\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e36,36\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAmplification positive\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eN/A***\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e35\u003c/p\u003e\n \u003cp\u003e28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e35,36\u003c/p\u003e\n \u003cp\u003e28,28\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e*: medullary carcinoma (8 case) and yolk sac tumour like carcinoma (1 case); **: medullary carcinoma (8 case);\u003c/p\u003e\n\u003cp\u003e***: cases with HER2 IHC score 2 + / 3 +, in which FISH / SISH not performed.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2.\u0026nbsp;\u003c/strong\u003eEvaluation of clinicopathologic features according to molecular subgroups\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" rowspan=\"2\" valign=\"top\" style=\"width: 142px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eEBV (+)\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=9)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e\u003cstrong\u003edMMR\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e(n=30)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eE-cadherin\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eAberrant\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e(n=30)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP53\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eAberrant\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e(n=115)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP53\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eWild\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e(n=56)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003ep\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u003cstrong\u003en\u0026nbsp;(%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e\u003cstrong\u003en\u0026nbsp;(%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u003cstrong\u003en (%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u003cstrong\u003en (%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u003cstrong\u003en\u0026nbsp;(%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAge (year)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eYears\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e(Median)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e52-81\u003c/p\u003e\n \u003cp\u003e(67)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e34-87\u003c/p\u003e\n \u003cp\u003e(71)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e29-76\u003c/p\u003e\n \u003cp\u003e(59)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e21-90\u003c/p\u003e\n \u003cp\u003e(65)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e33-85\u003c/p\u003e\n \u003cp\u003e(63,5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0,022\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLauren\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003ehistologic\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003etype\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eDiffuse\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e1 (11,1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e4 (13,3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e12 (40,0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e4 (3,5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e10 (17,9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0,001\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eIntestinal\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e1 (11,1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e19 (63,3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e6 (20,0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e72 (62,6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e18 (32,1)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMixed\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e5 (55,6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e4 (13,3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e11 (36,7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e36 (31,3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e28 (50,0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eUndefined\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e2 (22,2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e3 (10,0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e1 (3,3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e3 (2,6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"5\" valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eWHO-\u003c/strong\u003e\u003cstrong\u003e19\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003ehistologic\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003etype\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMucinous\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e1 (3,3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e4 (13,3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e9 (7,8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e2 (3,6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"5\" valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0,001\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePoorly\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003ecohesive\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e1 (11,1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e4 (13,3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e12 (40,0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e4 (3,5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e10 (17,9)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTubular/\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003ePapillary\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e1 (11,1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e18 (60,0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e2 (6,6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e63 (54,8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e16 (28,6)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMixed\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e5 (55,6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e4 (13,3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e11 (36,6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e36 (31,3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e28 (50)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eOthers\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e2 (22,2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e3 (10,0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e1 (3,3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e3 (2,6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"3\" valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGrade\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLow grade\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e13 (43,3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e3 (10,0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e45 (39,1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e18 (32,1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"3\" valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0,001\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHigh grade\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e7 (77,8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e14 (46,6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e27 (90,0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e67 (58,3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e38 (67,9)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eUngraded\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e2 (22,2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e3 (10,0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e3 (2,6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePerineural\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003einvasion\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNegative\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e1 (11,1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e17 (56,7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e8 (26,6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e30 (26,1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e7 (12,5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0,001\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePositive\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e8 (88,9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e13 (43,3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e22 (73,4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e85 (73,9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e49 (87,5)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLymphocytic\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eresponse\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNegative\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e2 (22,2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e5 (16,6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e16 (53,4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e30 (26,1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e30 (53,6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0,001\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePositive\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e7 (77,8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e25 (83,4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e14 (46,6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e85 (73,9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e26 (46,4)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHER2\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eIHC\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eScore 0\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e7 (77,8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e15 (50,0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e22 (73,3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e50 (43,5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e37 (66,1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"4\" valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0,018\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eScore 1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e1 (3,3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e1 (3,3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e5 (4,3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e3 (5,4)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eScore 2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e10 (33,3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e5 (16,6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e25 (21,7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e8 (14,3)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eScore 3\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e2 (22,2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e4 (13,3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e2 (6,6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e35 (30,4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e8 (14,3)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTablo 3 Clinical features of three cases with Pan-TRK expression\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCase ID\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSex\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLocation\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSize (cm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLauren\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTNM\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMolecular group\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e\u003cstrong\u003epan-TRK\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eCorpus\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eMixed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eT4aN3b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eGp4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eCytoplasmic punctate\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eAntrum\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eOther\u0026nbsp;(medullary type)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eT4aN3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eGp1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eNuclear\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eAntrum\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eIntestinal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eT3N1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eGp5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eNuclear\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTablo 4 Clinical features of 12 cases with NTRK1/2/3 FISH Positivity\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCase ID\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSex\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLocation\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSize (cm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLauren\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTNM\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMolecular group\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNTRK\u0026nbsp;split\u0026nbsp;rate\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eF\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eAntrum\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eMixed\u0026nbsp;(+\u0026nbsp;AFP production)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eT4aN3a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eGp4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eNTRK1\u0026nbsp;12%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eAntrum\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eMixed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eT4aN3a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eGp5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eNTRK1\u0026nbsp;21%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eF\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eCorpus\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eIntestinal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eT4aN3a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eGp4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eNTRK1\u0026nbsp;10%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eAntrum\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eMixed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eT3N3a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eGp5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eNTRK1\u0026nbsp;18%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eAntrum\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e8.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eMixed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eT3N3a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eGp4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eNTRK3\u0026nbsp;17%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eAntrum\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eMixed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eT4aN3a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eGp5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eNTRK3\u0026nbsp;14%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eF\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eCardia\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eIntestinal\u0026nbsp;(+\u0026nbsp;AFP production)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eT3N0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eGp4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eNTRK1\u0026nbsp;22%,\u003c/p\u003e\n \u003cp\u003eNTRK3\u0026nbsp;18%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eCardia\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e6.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eMixed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eT4aN3b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eGp1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eNTRK3\u0026nbsp;12%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eF\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eCorpus\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eMixed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eT4aN3b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eGp4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eNTRK1\u0026nbsp;21%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eCorpus\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eIntestinal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eT3N1a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eGp4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eNTRK1\u0026nbsp;16%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eCardia\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e5.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eIntestinal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eT3N1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eGp2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eNTRK1\u0026nbsp;14%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eAntrum\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e11.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eDiffus\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eT4aN2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eGp3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003eNTRK1\u0026nbsp;10%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-cancer","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bcan","sideBox":"Learn more about [BMC Cancer](http://bmccancer.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bcan/default.aspx","title":"BMC Cancer","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Gastric adenocarcinoma, molecular classification, NTRK gene fusion, Pan-TRK, NTRK FISH","lastPublishedDoi":"10.21203/rs.3.rs-9258096/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9258096/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eIdentification of neurotrophic tyrosine receptor kinase (NTRK) gene fusions has become clinically important because of the tumor-agnostic effectiveness of TRK inhibitors. In gastric adenocarcinoma (G-ACa), NTRK fusions are known to be exceedingly rare (0\u0026ndash;1%), and their clinicopathological associations as well as the performance and reliability of diagnostic approaches remain unclear. Pan-TRK immunohistochemistry (IHC) has been proposed as a screening tool for the detection of NTRK fusions.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eA total of 240 primary G-ACa cases were classified using an IHC/ISH-based molecular algorithm with EBER-ISH, mismatch repair proteins (MLH1, MSH2, MSH6, PMS2), p53, and E-cadherin expression. All tumors were screened for NTRK fusions using pan-TRK IHC. Break-apart NTRK fluorescence in situ hybridization (FISH) was performed in all pan-TRK\u0026ndash;positive cases and in a randomly selected subset of 35 pan-TRK\u0026ndash;negative tumors. Associations between NTRK-related findings, molecular subgroups, clinicopathological parameters, and survival outcomes were analyzed.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003e240 G-ACas were classified and the subtypes were as follows: 3.8% of the cases (n\u0026thinsp;=\u0026thinsp;9) were in Gp1; 12.5% of the cases (n\u0026thinsp;=\u0026thinsp;30) were in Gp2; 12.5% of the cases (n\u0026thinsp;=\u0026thinsp;30) were in Gp3; 47.9% of the cases (n\u0026thinsp;=\u0026thinsp;115) were in Gp4, and the remaining cases with wild type p53 expression represented 23.3% of the cases (n\u0026thinsp;=\u0026thinsp;56) (Gp5). IHC/ISH-based molecular classification showed significant correlations with patient age, Lauren/WHO histologic type, grade, perineural invasion, lymphocytic stromal response and HER2 IHC results (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). TRK expression was detected in 1.3% (3/240) of cases and was uniformly weak and focal. None of these cases demonstrated NTRK1/2/3 fusions on FISH analysis. In contrast, borderline or low-level NTRK split signals (10\u0026ndash;22%) were identified in 12 of 35 (34.3%) pan-TRK\u0026ndash;negative cases. NTRK FISH positivity showed no statistically significant association with IHC/ISH-based molecular subgroups and clinicopathological features.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eAn IHC/ISH-based molecular classification showed clinicopathological correlations, supporting its practical use in G-ACa. However, pan-TRK IHC and FISH demonstrated important limitations as screening tools. Borderline or low-level NTRK FISH positivity without TRK protein expression lacked clear biological or clinical relevance and showed no association with molecular subgroups or clinicopathological features. These findings indicate that NTRK testing in G-ACa should be interpreted cautiously within a comprehensive diagnostic framework to avoid overestimation of clinically actionable alterations.\u003c/p\u003e","manuscriptTitle":"Integrated Evaluation of TRK Expression in Gastric Adenocarcinoma: Correlation with Immunohistochemistry- and In Situ Hybridization–Based Molecular Classification and Diagnostic Challenges","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-05-11 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