A combined histologic and molecular approach identifies three groups of gastric cancer with different prognosis

Heterogeneity and Adjuvant Therapeutic Approaches in MSI-H/dMMR Resectable Gastric Cancer: Emerging Trends in Immunotherapy

Gastric cancer (GC) remains one of the world's most common and fatal malignant tumors. With a refined understanding of molecular typing in recent years, microsatellite instability (MSI) has become a major molecular typing approach for gastric cancer. MSI is well recognized for its important role during the immunotherapy of advanced GC. However, its value remains unclear in resectable gastric cancer. The reported incidence of microsatellite instability-high (MSI-H)/deficient mismatch repair (dMMR) in resectable gastric cancer varies widely, with no consensus reached on the value of postoperative adjuvant therapy in patients with MSI-H/dMMR resectable GC. It has been established that MSI-H/dMMR tumor cells can elicit an endogenous immune antitumor response and ubiquitously express immune checkpoint ligands such as PD-1 or PD-L1. On the basis of these considerations, MSI-H/dMMR resectable GCs are responsive to adjuvant immunotherapy, although limited research has hitherto been conducted. In this review, we comprehensively describe the differences in geographic distribution and pathological stages in patients with MSI-H/dMMR with resectable gastric cancer and explore the value of adjuvant chemotherapy and immunotherapy on MSI-H/dMMR to provide a foothold for the individualized treatment of this patient population.

Role of Endoscopic Biopsies and Morphologic Features in Predicting Microsatellite Instability Status in Gastric Cancer: A Multicenter Comparative Study of Endoscopic Biopsies and Surgical Specimens

Evaluation of mismatch repair (MMR) protein and microsatellite instability (MSI) status plays a pivotal role in the management of gastric cancer (GC) patients. In this study, we aimed to evaluate the accuracy of gastric endoscopic biopsies (EBs) in predicting MMR/MSI status and to uncover histopathologic features associated with MSI. A multicentric series of 140 GCs was collected retrospectively, in which EB and matched surgical specimens (SSs) were available. Laurén and WHO classifications were applied and detailed morphologic characterization was performed. EB/SS were analyzed by immunohistochemistry (IHC) for MMR status and by multiplex polymerase chain reaction (mPCR) for MSI status. IHC allowed accurate evaluation of MMR status in EB (sensitivity: 97.3%; specificity: 98.0%) and high concordance rates between EB and SS (Cohen κ=94.5%). By contrast, mPCR (Idylla MSI Test) showed lower sensitivity in evaluating MSI status (91.3% vs. 97.3%), while maintaining maximal specificity (100.0%). These results suggest a role of IHC as a screening method for MMR status in EB and the use of mPCR as a confirmatory test. Although Laurén/WHO classifications were not able to discriminate GC cases with MSI, we identified specific histopathologic features that are significantly associated with MMR/MSI status in GC, despite the morphologic heterogeneity of GC cases harboring this molecular phenotype. In SS, these features included the presence of mucinous and/or solid components ( P =0.034 and <0.001) and the presence of neutrophil-rich stroma, distant from tumor ulceration/perforation ( P <0.001). In EB, both solid areas and extracellular mucin lakes were also discriminating features for the identification of MSI-high cases ( P =0.002 and 0.045).

Identification of Hub Genes Associated With the Development of Stomach Adenocarcinoma by Integrated Bioinformatics Analysis

Objective

This study was conducted in order to gain a better understanding of the molecular mechanisms of stomach adenocarcinoma (STAD), which is necessary to predict the prognosis of STAD and develop novel gene therapy strategies.

Methods

In this study, the gene expression profile of GSE118916 in the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas Program (TCGA) was used to explore the differential co-expression genes of STAD and normal tissues.

Results

A total of 407 STAD samples were collected, consisting of 375 from stomach adenocarcinoma tissues and 32 from normal tissues, as well as RNA-seq count data for 19,600 genes. Forty-two differentially expressed genes were screened by weighted gene co-expression network analysis (WGCNA) and differentially expressed gene analysis. According to the functional annotation analysis of the clusterProfiler R package, these genes were analyzed for GO function enrichment, digestion (biological process), tube bottom material membrane (cell component), and oxidoreductase activity (molecular function). The KEGG pathway was enriched in gastric acid secretion and chemical carcinogenesis. In addition, Cytoscape's cytoHubba plug-in was used to identify seven hub genes (EWSR1, ESR1, CLTC, PCMT1, TP53, HUWE1, and HDAC1) in a protein-protein interaction (PPI) network consisting of 7 nodes and 11 edges. Compared with normal tissues, CLTC and TP53 genes were upregulated in stomach adenocarcinoma (P < 0.05). TP53 was expressed differently in stages II and IV, EWSR1 was expressed differently in stages II and III, and ESR1 was expressed differently in stages I-III. Among the seven hub genes, Kaplan-Meier analysis and TCGG showed that the expression levels of HDAC1 and CLTC were significantly correlated with OS in patients with stomach adenocarcinoma (P < 0.05). GEPIA2 analysis showed that ESR1 expression was closely correlated with OS and DFS in gastric adenocarcinoma (P < 0.05). Then, the expression of the genes and their correlations were revealed by the R2 Platform (http://r2.amc.nl). Finally, we collected 18 pairs of gastric mucosal tissues from normal people and cancer tissues from patients with stomach adenocarcinoma. The expression levels of the above seven hub genes and their relative protein expression were detected by RT-PCR and immunohistochemistry (IHC). The results showed that the gene and protein expression levels in stomach adenocarcinoma tissues were increased than those in the normal group.

Conclusion

In summary, we believe that the identified hub genes were related to the occurrence of stomach adenocarcinoma, especially the expression of ESR1, HDAC1, and CLTC genes, which are related to the prognosis and overall survival of patients and may become the potential for the future diagnosis and treatment of STAD.

Expression of ferroptosis-related gene correlates with immune microenvironment and predicts prognosis in gastric cancer

The study is to explore the role of ferroptosis-related genes (FRGs) in the occurrence and development of gastric cancer (GC), and to construct a new prognosis signature to predict the prognosis in GC. Clinical information and corresponding RNA data of GC patients were downloaded from TCGA and GEO databases. Consensus clustering was performed to identify new molecular subgroups. ESTIMATE, CIBERSORT, McpCounter and TIMER algorithm were used to analyze the infiltration of immune cells in two molecular subgroups. LASSO algorithm and multivariate Cox analysis were used to construct a prognostic risk signature. Functional analysis was conducted to elucidate the underlying mechanisms. Finally, the FRPGs were verified by Quantitative Real-Time PCR. We obtained 16 FRGs and divided GC patients into two subgroups by consistent clustering. Cluster C1 with a higher abundance of immune cell infiltration but lower probability in response to immunotherapy, it was reasonable to speculate that Cluster C1 was in accordance with the immune rejection type. Functional analysis showed that the biological process of DEGs in training cohort mainly included immune globulin, and human immune response mediated by circulating immune globulin. GSEA analysis showed that compared with Cluster C2, Cluster C1 showed lower expression in lipid metabolism. The nomogram combined with risk signature and clinical features can accurately predict the prognosis of GC patients. We identified two molecular subtypes, Clusters C1 and C2. In Cluster C1, patients with poor prognosis present with a hyperimmune status and low lipid metabolism, and we speculate that Cluster C1 was in accordance with the immune rejection type. The risk model based on FRPGs can accurately predict the prognosis of GC. These results indicated that ferroptosis is associated with TIME, and deserved considerable attention in determining immunotherapy treatment strategy for GC patients.

Histological and mutational profile of diffuse gastric cancer: current knowledge and future challenges

Gastric cancer (GC) pathogenesis is complex and heterogeneous, reflecting morphological, molecular and genetic diversity. Diffuse gastric cancer (DGC) and intestinal gastric cancer (IGC) are the major histological types. GC may be sporadic or hereditary; sporadic GC is related to environmental and genetic low-risk factors and hereditary GC is caused by inherited high-risk mutations, so far identified only for the diffuse histotype. DGC phenotypic heterogeneity challenges the current understanding of molecular mechanisms underlying carcinogenesis. The definition of a DGC-specific mutational profile remains controversial, possibly reflecting the heterogeneity of DGC-related histological subtypes [signet-ring cell carcinoma (SRCC) and poorly cohesive carcinoma not otherwise specified (PCC-NOS)]. Indeed, DGC and DGC-related subtypes may present specific mutational profiles underlying the particularly aggressive behaviour and dismal prognosis of DGC vs IGC and PCC-NOS vs SRCC. In this systematic review, we revised the histological presentations, molecular classifications and approved therapies for gastric cancer, with a focus on DGC. We then analysed results from the most relevant studies, reporting mutational analysis data specifying mutational frequencies, and their relationship with DGC and IGC histological types, and with specific DGC subtypes (SRCC and PCC-NOS). We aimed at identifying histology-associated mutational profiles with an emphasis in DGC and its subtypes (DGC vs IGC; sporadic vs hereditary DGC; and SRCC vs PCC-NOS). We further used these mutational profiles to identify the most commonly affected molecular pathways and biological functions, and explored the clinical trials directed specifically to patients with DGC. This systematic analysis is expected to expose a DGC-specific molecular profile and shed light into potential targets for therapeutic intervention, which are currently missing.

The Prognostic Impact of Histology in Esophageal and Esophago-Gastric Junction Adenocarcinoma

Stage significantly affects survival of esophageal and esophago-gastric junction adenocarcinomas (EA/EGJAs), however, limited evidence for the prognostic role of histologic subtypes is available. The aim of the study was to describe a morphologic approach to EA/EGJAs and assess its discriminating prognostic power. Histologic slides from 299 neoadjuvant treatment-naïve EA/EGJAs, resected in five European Centers, were retrospectively reviewed. Morphologic features were re-assessed and correlated with survival. In glandular adenocarcinomas (240/299 cases-80%), WHO grade and tumors with a poorly differentiated component ≥6% were the most discriminant factors for survival (both p < 0.0001), distinguishing glandular well-differentiated from poorly differentiated adenocarcinomas. Two prognostically different histologic groups were identified: the lower risk group, comprising glandular well-differentiated (34.4%) and rare variants, such as mucinous muconodular carcinoma (2.7%) and diffuse desmoplastic carcinoma (1.7%), versus the higher risk group, comprising the glandular poorly differentiated subtype (45.8%), including invasive mucinous carcinoma (5.7%), diffuse anaplastic carcinoma (3%), mixed carcinoma (6.7%) (CSS p < 0.0001, DFS p = 0.001). Stage (p < 0.0001), histologic groups (p = 0.001), age >72 years (p = 0.008), and vascular invasion (p = 0.015) were prognostically significant in the multivariate analysis. The combined evaluation of stage/histologic group identified 5-year cancer-specific survival ranging from 87.6% (stage II, lower risk) to 14% (stage IVA, higher risk). Detailed characterization of histologic subtypes contributes to EA/EGJA prognostic prediction.

Precancerous lesions of the stomach, gastric cancer and hereditary gastric cancer syndromes

Gastric cancer accounts for about 6% of cancers worldwide, being the fifth most frequently diagnosed malignancy and the third leading cause of cancer related death. Gastric carcinogenesis is a multistep and multifactorial process and is the result of the complex interplay between genetic susceptibility and environmental factors. The identification of predisposing conditions and of precancerous lesions is the basis for screening programs and early stage treatment. Furthermore, although most gastric cancers are sporadic, familial clustering is observed in up to 10% of patients. Among them, hereditary cases, related to known cancer susceptibility syndromes and/or genetic causes are thought to account for 1-3% of all gastric cancers. The pathology report of gastric resections specimens therefore requires a standardized approach as well as in depth knowledge of prognostic and treatment associated factors.

Construction and validation of a TP53-associated immune prognostic model for gastric cancer

Increasing evidence indicates that TP53 mutation impacts the patients' prognosis by regulating the gastric cancer (GC) immunophenotype. An immune prognostic signature (IPS) was constructed based on TP53 status. The effects of the IPS on the immune microenvironment of GC were analyzed. We also constructed a nomogram integrating the IPS and other clinical factors. An IPS was constructed in the TCGA cohort and validated in the meta-GEO cohort. TP53 mutation resulted in the downregulation of the immune response in GC. Concretely, high-risk patients were characterized by increased monocyte, macrophage M0 and T cell follicular helper infiltration; increased stromal score, ESTIMATE score and immune score; higher TIM3 and BTLA expression; and decreased dendritic cell and T cell CD4 memory-activated infiltration and tumor purity. The nomogram also showed good predictive performance. These results suggest that the IPS is an effective prognostic indicator for GC patients, which might provide a theoretical foundation for immunotherapy.

Separation of Low- Versus High-grade Crohn's Disease-associated Small Bowel Carcinomas is Improved by Invasive Front Prognostic Marker Analysis

BACKGROUND AND AIMS

Crohn's disease-associated small bowel carcinoma is a rare event, usually reported to have a severe prognosis. However, in previous investigations we have found a minority of cases displaying a relatively favourable behaviour, thus outlining the need to improve the histopathological prediction of Crohn's disease-associated small bowel carcinoma prognosis.

METHODS

As in recent studies on colorectal cancer, a substantial improvement in prognostic evaluations has been provided by the histological analysis of the tumour invasive front; we therefore systematically analysed the tumour budding and poorly differentiated clusters in the invasive front of 47 Crohn's disease-associated small bowel carcinomas collected through the Small Bowel Cancer Italian Consortium.

RESULTS

Both tumour budding and poorly differentiated cluster analyses proved highly effective in prognostic evaluation of Crohn's disease-associated small bowel carcinomas. In addition, they retained prognostic value when combined with two other parameters, i.e. glandular histology and stage I/II, both known to predict a relatively favourable small bowel carcinoma behaviour. In particular, association of tumour budding and poorly differentiated clusters in a combined invasive front score allowed identification of a minor subset of cancers [12/47, 25%] characterised by combined invasive front low grade coupled with a glandular histology and a low stage [I or II] and showing no cancer-related death during a median follow-up of 73.5 months.

CONCLUSIONS

The improved distinction of lower- from higher-grade Crohn's disease-associated small bowel carcinomas provided by invasive front analysis should be of potential help in choosing appropriate therapy for these rare and frequently ominous neoplasms.

Ki-67/MKI67 as a Predictive Biomarker for Clinical Outcome in Gastric Cancer Patients: an Updated Meta-analysis and Systematic Review involving 53 Studies and 7078 Patients

Gastric cancer (GC) threatens human health worldwide and we performed this meta-analysis to evaluate the clinical value of Ki-67/MKI67 in patients with GC. The combined hazard ratio (HR), odds ratio (OR) and 95% confidence interval (95% CI) were calculated to assess the relationships of Ki-67/MKI67 expression with prognoses and clinicopathological characteristics. Genes co-expressed with MKI67 were collected for Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and protein-protein interaction (PPI) network analyses. In total, 53 studies with 7078 patients were included in this study. The pooled HRs indicated that an elevated expression of Ki-67/MKI67 predicted an unfavorable overall survival (HR: 1.54, 95% CI: 1.33-1.78, P<0.0001) and disease-free survival (HR: 2.28, 95% CI: 1.43-3.64, P<0.0001) in GC patients. Additionally, in patients with advanced GC, a high Ki-67/MKI67 expression was also significantly connected with OS (HR: 1.37, 95% CI: 1.18-1.60, P<0.0001). The combined ORs showed that Ki-67/MKI67 expression was related to TNM stage (stage III/IV versus stage I/II: OR=1.93, 95% CI=1.34-2.78, P<0.0001), tumor differentiation (poor versus well/moderate: OR=1.94, 95% CI=1.32-2.85, P=0.001), lymph node metastasis (yes versus no: OR=1.67, 95% CI=1.23-2.25, P=0.001), distant metastasis (yes versus no: OR=1.67, 95% CI=1.24-2.26, P=0.001) and tumor invasion depth (T3/T4 versus T_is/T1/T2: OR=1.98, 95% CI=1.60-2.44, P<0.0001). The results of GO, KEGG pathway and PPI network analyses indicated that Ki-67/MKI67 may be involved in the development of GC via influencing P53 signaling pathway. Ki-67/MKI67 could be a potential indicator to predict the prognosis of patients with GC and identify high-risk cases. Detecting Ki-67/MKI67 expression in clinic may be helpful in optimizing individual treatment and further improving the survival expectancy of patients with GC.

Perioperative complications and outcome after surgery for treatment of gastric carcinoma in dogs: A Veterinary Society of Surgical Oncology retrospective study of 40 cases (2004-2018)

OBJECTIVE

To describe the clinical characteristics, perioperative complications, and outcomes in dogs surgically treated for gastric carcinoma.

STUDY DESIGN

Multi-institutional retrospective case series.

ANIMALS

Forty client-owned dogs with histologically confirmed gastric carcinoma.

METHODS

Medical records were reviewed for preoperative diagnostics, surgery, histopathology, postoperative complications, adjuvant chemotherapy, disease progression, and survival. Variables were assessed for associations with outcome by using Cox proportional hazards regression analysis.

RESULTS

Surgical treatment included partial gastrectomy (28 dogs), Billroth I (9 dogs), subtotal gastrectomy (2 dogs), and submucosal resection (1 dog). Major postoperative complications occurred in 8 of 40 dogs, including septic peritonitis secondary to dehiscence in 4 dogs. The median progression free interval was 54 days, and the median survival time (MST) was 178 days (range, 1-1902). According to multivariable analysis results, experiencing an intraoperative complication was associated with an increased risk of death (hazard ratio [HR] 3.5, 95% CI 1.1-9.8, P = .005), and administration of adjuvant chemotherapy correlated with an improved survival (HR 0.4, 95% CI 0.2-0.9, P = .03).

CONCLUSION

In this population of dogs, MST exceeded historically reported data, major postoperative complication rates were comparable to established literature, and administration of adjuvant chemotherapy was associated with improved survival.

CLINICAL SIGNIFICANCE

Results from this study may be used to counsel owners more accurately regarding prognosis for dogs undergoing surgical excision for gastric carcinoma.

Assessing molecular subtypes of gastric cancer: microsatellite unstable and Epstein-Barr virus subtypes. Methods for detection and clinical and pathological implications

Background

The molecular classification of gastric cancer recognises two subtypes prone to immune checkpoint blockade: the microsatellite unstable and the Epstein-Barr virus (EBV)-related tumours. We aim to assess the concordance between immunohistochemistry and PCR for microsatellite status evaluation, and explore the value of microsatellite instability (MSI) and EBV as predictive survival factors.

Material and methods

We collected 246 consecutively diagnosed gastric cancer cases in all stages and evaluated the microsatellite status using immunohistochemistry for mismatched repair (MMR) proteins and PCR. EBV expression was studied through in situ hybridisation.

Results

Forty-five (18%) cases presented MSI and 13 (6%) were positive for EBV. MSI was associated with female sex, older age, distal location and distal non-diffuse type of the modified Lauren classification. EBV expression was most frequent in proximal location and proximal non-diffuse type. The sensitivity, specificity, positive predictive value and negative predictive value of immunohistochemistry for the microsatellite study were 91%, 98%, 91% and 98%, respectively. In the multivariate analysis, MSI was an independent predictor of favourable tumour-specific survival (TSS) in stages I–III (MSI: HR: 0.37, 95% CI 0.12 to 0.95, p=0.04).

Conclusions

The MSI status and the EBV expression should be incorporated in routine pathological report for two reasons. First, MSI defines a different pathological entity with a better outcome. Second, MSI and EBV may be useful biomarkers to identify patients who will respond to immune checkpoint blockade inhibitors. For this purpose, immunohistochemical study for MMR proteins and in situ hybridisation study for EBV evaluation are feasible and cost-effective methods.

Gastric mixed neuroendocrine-non-neuroendocrine neoplasm (MiNEN) with pancreatic acinar differentiation: a case report

Background

Gastric mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs) are infrequently encountered in routine practice. Some gastric neuroendocrine carcinomas (NECs) have a variety of differentiation patterns; however, pancreatic acinar differentiation in gastric NECs is rare. The molecular abnormalities of NECs with pancreatic acinar differentiation are not well understood.

Case presentation

A 67-year-old male with a gastric MiNEN with pancreatic acinar differentiation without any symptoms. The tumor consisted of two components, including both glandular and solid histological features. Although the former component was a common type of adenocarcinoma, the latter showed endocrine differentiation and expressed pancreatic acinar enzymes immunohistochemically. A positive signal with the anti-BCL10 antibody, which detects one of the pancreatic acinar enzymes, was also present specifically in the latter component. We also examined TP53 genomic mutations, DNA methylation status, and allelic imbalance (AI), which is an indicator of tumor aggressiveness. Although both components of this tumor showed no genomic mutation and a low methylation epigenotype, the frequency of AI was higher in the acinar-endocrine component than in the adenocarcinomatous component. The finding of AI indicated the progression of the conventional adenocarcinoma to an acinar-endocrine component and identified the aggressive potential of the acinar-endocrine component.

Conclusions

We report a rare case of gastric MiNEN with pancreatic acinar differentiation. AI analysis revealed tumor progression and aggressiveness. In addition, the usefulness of the anti-BCL10 antibody for detecting the acinar-endocrine component was suggested.

New insights into the inflamed tumor immune microenvironment of gastric cancer with lymphoid stroma: from morphology and digital analysis to gene expression

BACKGROUND

Gastric cancer with lymphoid stroma (GCLS) is characterized by prominent stromal infiltration of T-lymphocytes. The aim of this study was to investigate GCLS biology through analysis of clinicopathological features, EBV infection, microsatellite instability (MSI), immune gene-expression profiling and PD-L1 status in neoplastic cells and tumor immune microenvironment.

METHODS

Twenty-four GCLSs were analyzed by RNA in situ hybridization for EBV (EBER), PCR/fragment analysis for MSI, immunohistochemistry (PD-L1, cytokeratin, CD3, CD8), co-immunofluorescence (CK/PD-L1, CD68/PD-L1), NanoString gene-expression assay for immune-related genes and PD-L1 copy number alterations. CD3+ and CD8+ T-cell densities were calculated by digital analysis. Fifty-four non-GCLSs were used as control group.

RESULTS

GCLSs displayed distinctive clinicopathological features, such as lower pTNM stage (p = 0.02) and better overall survival (p = 0.01). EBV+ or MSI-high phenotype was found in 66.7 and 16.7% cases, respectively. GCLSs harbored a cytotoxic T-cell-inflamed profile, particularly at the invasive front of tumors (p < 0.01) and in EBV+ cases (p = 0.01). EBV+ GCLSs, when compared to EBV- GCLSs, showed higher mRNA expression of genes related to Th1/cytotoxic and immunosuppressive biomarkers. PD-L1 protein expression, observed in neoplastic and immune stromal cells (33.3 and 91.7%, respectively), and PD-L1 amplification (18.8%) were restricted to EBV+/MSI-high tumors and correlated with high values of PD-L1 mRNA expression.

CONCLUSIONS

This study shows that GCLS has a distinctive clinico-pathological and molecular profile. Furthermore, through an in-depth study of tumor immune microenvironment-by digital analysis and mRNA expression profiling-it highlights the role of EBV infection in promoting an inflamed tumor microenvironment, with putative therapeutic implications.

The Transcriptomic Landscape of Gastric Cancer: Insights into Epstein-Barr Virus Infected and Microsatellite Unstable Tumors

Background: Epstein-Barr Virus (EBV) positive and microsatellite unstable (MSI-high) gastric cancer (GC) are molecular subgroups with distinctive molecular profiles. We explored the transcriptomic differences between EBV+ and MSI-high GCs, and the expression of current GC immunotherapy targets such as PD-1, PD-L1, CTLA4 and Dies1/VISTA. Methods: Using Nanostring Technology and comparative bioinformatics, we analyzed the expression of 499 genes in 46 GCs, classified either as EBV positive (EBER in situ hybridization) or MSI-high (PCR/fragment analysis). PD-L1 protein expression was assessed by immunohistochemistry. Results: From the 46 GCs, 27 tested MSI-high/EBV−, 15 tested MSS/EBV+ and four tested MSS/EBV−. The Nanostring CodeSet could segregate GCs according to MSI and, to a lesser extent, EBV status. Functional annotation of differentially expressed genes associated MSI-high/EBV− GCs with mitotic activity and MSS/EBV+ GCs with immune response. PD-L1 protein expression, evaluated in stromal immune cells, was lower in MSI-high/EBV− GCs. High mRNA expression of PD-1, CTLA4 and Dies1/VISTA and distinctive PD-1/PD-L1 co-expression patterns (PD-1^high/PD-L1^low, PD-1^high/PDL1^high) were associated with MSS/EBV+ molecular subtype and gastric cancer with lymphoid stroma (GCLS) morphological features. Conclusions: EBV+ and MSI-high GCs present distinct transcriptomic profiles. GCLS/EBV+ cases frequently present co-expression of multiple immunotherapy targets, a finding with putative therapeutic implications.

Identification of Differentiation-Related Proteins in Gastric Adenocarcinoma Tissues by Proteomics

There is a significant correlation between the degree of tumor differentiation and the survival of patients with gastric cancers. In this report, we compared proteomic differences between poorly differentiated gastric adenocarcinoma tissues and well-differentiated gastric adenocarcinoma tissues in order to identify differentiation-related proteins that may be closely correlated with differentiation of gastric cancer pathogenesis. We identified 7 proteins, of which calreticulin precursor, tapasinERP57 heterodimer, pyruvate kinase isozymes M1/M2 isoform M2, class Pi glutathione S-transferase, and chain A crystal structure of human enolase 1 were upregulated in poorly differentiated gastric adenocarcinoma compared with well-differentiated gastric adenocarcinoma, while myosin-11 isoform SM2A and actin alpha cardiac were downregulated. Two of them, pyruvate kinase isozymes M1/M2 isoform M2 and enolase 1 are enzymes involved in glycolytic pathway. The upregulation of pyruvate kinase isozymes M1/M2 isoform M2 and enolase 1 in poorly differentiated gastric adenocarcinoma was confirmed by Western blotting and immunohistochemistry. Furthermore, we observed 107 cases with gastric adenocarcinoma and found that the high expression of pyruvate kinase isozymes M1/M2 isoform M2 and enolase 1 correlates with tumor size (P = .0001 and P = .0017, respectively), depth of invasion (P = .0024 and P = .0261, respectively), and poor prognosis of patients. In conclusion, with this proteomic analysis, pyruvate kinase isozymes M1/M2 isoform M2 and enolase 1 were identified upregulated in poorly differentiated gastric adenocarcinoma comparing with well-differentiated gastric adenocarcinoma. The expression level of pyruvate kinase isozymes M1/M2 isoform M2 and enolase 1 was significantly correlated with overall survival. Some of them would be differentiation-related cancer biomarkers and are associated with tumor metastasis, invasion, and prognosis.

Clinicopathologic Characteristics of Microsatellite Instable Gastric Carcinomas Revisited: Urgent Need for Standardization

Microsatellite instable gastric cancer (MSI-GC) is a specific molecular subtype of GC. We studied the phenotypes, genotypes, and clinicopathologic characteristics of MSI-GC in a white GC cohort and compared our findings with an extended literature review. The study cohort consisted of 482 patients. Specimens were available from 452 cases and were used for immunostaining (MLH1, PMS2, MSH2, MSH6) and molecular biological analyses (BAT-25, BAT-26, NR-21, NR-24, NR-27; Epstein-Barr virus in situ hybridization). Thirty-four (7.5%) GCs were MSI. Loss of MLH1 and/or PMS2 was found in 30 (88%) MSI-GC, 3 (9%) showed loss of MSH2 and/or MSH6. One (3%) MSI-GC was identified only by molecular biological testing. A single case was heterogeneous and contained microsatellite-stable and instable tumor areas. Twenty-one (62%) MSI-GCs showed unusual histologic features. MSI-GC was not found in diffuse-type or Epstein-Barr virus-positive GC. MSI-GC was significantly more prevalent in elderly patients, distal stomach, and was associated with a significantly lower number of lymph node metastases and a significantly better overall and tumor-specific survival. MSI-GC constitutes a small but relevant subgroup of GC with distinct clinicopathologic characteristics. Our literature review illustrates the shortcomings of missing standardized testing algorithms with prevalences of MSI-GC ranging from 0% to 44.5%. Future studies should test the hypothesis that patients with MSI-GCs may not need adjuvant/perioperative chemotherapy. However, this will require a standardized, quality-controlled diagnostic algorithm of MSI for GC.

The molecular background of mucinous carcinoma beyond MUC2

The increasing interest of the oncology community in tumour classification and prediction of outcome to targeted therapies has put emphasis on an improved identification of tumour types. Colorectal mucinous adenocarcinoma (MC) is a subtype that is characterized by the presence of abundant extracellular mucin that comprises at least 50% of the tumour volume and is found in 10–15% of colorectal cancer patients. MC development is poorly understood, however, the distinct clinical and pathological presentation of MC suggests a deviant development and molecular background. In this review we identify common molecular and genetic alterations in colorectal MC. MC is characterized by a high rate of MUC2 expression. Mutation rates in the therapeutically important RAS/RAF/MAPK and PI3K/AKT pathways are significantly higher in MC compared with non‐mucinous adenocarcinoma. Furthermore, mucinous adenocarcinoma shows higher rates of microsatellite instability and is more frequently of the CpG island methylator phenotype. Although the majority of MCs arise from the large intestine, this subtype also develops in other organs, such as the stomach, pancreas, biliary tract, ovary, breast and lung. We compared findings from colorectal MC with tumour characteristics of MCs from other organs. In these organs, MCs show different mutation rates in the RAS/RAF/MAPK and PI3K/AKT pathways as well, but a common mucinous pathway cannot be identified. Identification of conditions and molecular aberrations that are associated with MC generates insight into the aetiology of this subtype and improves understanding of resistance to therapies.

The contribution of cell phenotype to the behavior of gastric cancer

BACKGROUND

Several histochemical studies suggest a role of tumor cell phenotype and related differentiation markers in the prognostic assessment of gastric cancer. Unfortunately, most studies have dealt with single or a few markers and have paid limited attention to their interplay with tumor histological types, which are potentially informative of prognosis.

METHODS

In this study, 292 invasive (T1b to T4) gastric cancers with prolonged follow-up and carefully analyzed histotype, inclusive of histotype-based grade, were investigated histochemically with a panel of 14 phenotypic markers known to be expressed in normal gut tissues and gastric cancer.

RESULTS

Three of seven intestinal type markers investigated showed a trend for improved prognosis, one of which, CDX2, was stage independent. Three among gastric and pancreatobiliary duct markers (MUC1, MUC6, and pepsinogen II), predicted more severe prognosis stage independently, as did a combination of eight potentially informative (p < 0.1 at univariable Cox analysis) markers. Cancers with predominantly intestinal phenotype had significantly better prognosis than those with predominantly gastric, mixed, or poorly defined phenotypes; among the latter, those with high lymphocyte response, with favorable outcome, were separated from anaplastic cancers, with ominous prognosis. At multivariable analysis, CDX2 and the eight marker combination proved to be stage- and grade-independent predictors.

CONCLUSIONS

When individually considered, and with the exception of CDX2, the biomarkers investigated gave an appreciable, although moderate, contribution to the prognostic evaluation of gastric cancer. Combined analysis of all potentially informative markers gave more important information, highly additive to both stage and histotype-based grade.

Gastrointestinal cancers reactive for the PAb416 antibody against JCV/SV40 T-Ag lack JCV DNA sequences while showing a distinctive pathologic profile

AIM

Immunohistochemical and molecular studies have suggested an oncogenic role for JCV in gastrointestinal carcinomas, but at least in colorectal cancers, the data are far from being unambiguous.

METHODS

Two large series of formalin-fixed paraffin-embedded gastric and colorectal cancers were analysed for the expression of JCV large T Antigen (T-Ag) with a panel of five antibodies, and for the presence of T-Ag DNA sequences using two PCR systems.

RESULTS

Intense nuclear staining was observed in 54/116 (46%) colorectal, and in 92/234 (39%) gastric cancers, using the PAb416 monoclonal antibody against large T-Ag. In colorectal cancers, PAb416-positivity was directly related to the presence of chromosomal instability, lymph node metastases and a more advanced tumour stage, and inversely related to proximal tumour site and the presence of microsatellite instability (MSI). In gastric cancers, the glandular histotype, the presence of lymph node metastases, a low frequency of MSI and EBV infection, and a worse prognosis were significantly associated with PAb416 immunoreactivity. Moreover, at both these sites, PAb416 expression was significantly associated with p53 nuclear accumulation. No positivity was obtained with all the other four anti-T-Ag-antibodies, and molecular analysis failed to demonstrate the presence of JCV DNA sequences in tested cases.

CONCLUSIONS

Our immunohistochemical and molecular results do not support the idea that JCV T-Ag has a role in gastrointestinal carcinogenesis. It is possible that PAb416, besides binding the viral protein, may cross-react with a hitherto undefined protein whose expression is associated with a distinct pathological profile and, at least in gastric cancers, with worse prognosis.

Histotype-based prognostic classification of gastric cancer

AIM: To test the efficiency of a recently proposed histotype-based grading system in a consecutive series of gastric cancers.

METHODS: Two hundred advanced gastric cancers operated upon in 1980-1987 and followed for a median 159 mo were investigated on hematoxylin-eosin-stained sections to identify low-grade [muconodular, well differentiated tubular, diffuse desmoplastic and high lymphoid response (HLR)], high-grade (anaplastic and mucinous invasive) and intermediate-grade (ordinary cohesive, diffuse and mucinous) cancers, in parallel with a previously investigated series of 292 cases. In addition, immunohistochemical analyses for CD8, CD11 and HLA-DR antigens, pancytokeratin and podoplanin, as well as immunohistochemical and molecular tests for microsatellite DNA instability and in situ hybridization for the Epstein-Barr virus (EBV) EBER1 gene were performed. Patient survival was assessed with death rates per 100 person-years and with Kaplan-Meier or Cox model estimates.

RESULTS: Collectively, the four low-grade histotypes accounted for 22% and the two high-grade histotypes for 7% of the consecutive cancers investigated, while the remaining 71% of cases were intermediate-grade cancers, with highly significant, stage-independent, survival differences among the three tumor grades (P = 0.004 for grade 1 vs 2 and P = 0.0019 for grade 2 vs grade 3), thus confirming the results in the original series. A combined analysis of 492 cases showed an improved prognostic value of histotype-based grading compared with the Lauren classification. In addition, it allowed better characterization of rare histotypes, particularly the three subsets of prognostically different mucinous neoplasms, of which 10 ordinary mucinous cancers showed stage-inclusive survival worse than that of 20 muconodular (P = 0.037) and better than that of 21 high-grade (P < 0.001) cases. Tumors with high-level microsatellite DNA instability (MSI-H) or EBV infection, together with a third subset negative for both conditions, formed the T8 cell-rich HLR group, the largest group among low-grade histotypes. Coexisting HLR proved to be a factor in improved prognosis in tumors with microsatellite instability (P = 0.0015 vs HLR-/MSI-H tumors) or DR type human leukocyte antigen expression (P = 0.033 vs HLR^-/HLA-DR⁺ tumors).

CONCLUSION: Identification of low- and high-grade histotypes can improve the prognostic assessment of a substantial proportion of gastric cancers in routine diagnostic practice.

Prediction of response and prognosis by a score including only pretherapeutic parameters in 410 neoadjuvant treated gastric cancer patients

BACKGROUND

Response to neoadjuvant chemotherapy is an independent prognostic factor in locally advanced gastric cancer. However, no prospectively tested pretherapeutic parameters predicting response and/or survival in gastric cancer are available in clinical routine.

METHODS

We evaluated the prognostic significance of various clinical pathologic parameters in 410 patients who were treated with neoadjuvant chemotherapy followed by gastrectomy. Clinical and histopathologic response evaluation was performed by using standardized criteria. A prognostic score was created on the basis of the variables identified in the multivariate analysis.

RESULTS

Three pretherapeutic parameters were identified as positive predictive factors for response and prognosis: tumor localization in the middle third of the stomach (P=0.001), well-differentiated tumors (P=0.001), and intestinal tumor type according to Laurén classification (P=0.03). A prognostic index was constructed, dividing the patients into three risk groups: low (n=73), intermediate (n=274), and high (n=63). The three groups had significantly different clinical (P=0.007) and histopathologic response rates (P=0.001) and survival times, with a median survival time that was not reached in the low-risk group, 39.2 months in the intermediate-risk group, and 20.5 months in the high-risk group. The corresponding 5-year survival rates were 65.3, 41.2, and 21.2% (P<0.001), respectively.

CONCLUSIONS

A simple scoring system based on three clinicopathologic parameters accurately predicts response and prognosis in neoadjuvant treated gastric cancer. This system provides additional useful information that could be applied to select gastric cancer patients pretherapeutically for different treatment approaches. Prospective testing of the score in an independent patient cohort is warranted.

Prediction of response and prognosis by a score including only pretherapeutic parameters in 410 neoadjuvant treated gastric cancer patients

INTRODUCTION

Response to neoadjuvant chemotherapy (NAC) is an independent prognostic factor in locally advanced gastric cancer. However, no prospectively tested pretherapeutic parameters predicting response and/or survival in gastric cancer are available in clinical routine.

PATIENTS AND METHODS

We evaluated the prognostic significance of various clinicopathologic parameters in 410 patients who were treated with NAC followed by gastrectomy. Clinical and histopathological response evaluation was performed using standardized criteria. A prognostic score was created on the basis of the variables identified in the multivariate analysis.

RESULTS

Multivariate analysis identified three pretherapeutic parameters as positive predictive factors for response and prognosis: tumor localization in the middle third of the stomach (p = 0.001), well differentiated tumors (p = 0.001) and intestinal tumor type according to Laurén's classification (p = 0.03). From the obtained data a prognostic index was constructed, dividing the patients into three risk groups: low (n = 73), intermediate (n = 274), and poor (n = 63). The three groups had significantly different clinical (p = 0.007) and histopathological response rates (p = 0.001) and survival times, with a median survival time that was not reached in the low-risk group, 39.2 months in the intermediate-risk group and 20.5 months in the poor-risk group. The corresponding 5-year survival rates were 65.3, 41.2, and 21.2 % (p < 0.001), respectively.

CONCLUSION

A simple scoring system based on three clinicopathologic parameters, accurately predicts response and prognosis in neoadjuvant treated gastric cancer. This system provides additional useful information that could be applied to select gastric cancer patients pretherapeutically for different treatment approaches. Prospective testing of the score in an independent patient cohort is warranted.

Pleomorphic epithelioid diffuse malignant pleural mesothelioma: a clinicopathological review and conceptual proposal to reclassify as biphasic or sarcomatoid mesothelioma

INTRODUCTION

In patients with epithelioid diffuse malignant pleural mesothelioma (DMPM), clinical stage is the current primary prognostic factor. We sought to investigate whether histologic subtyping can prognostically stratify patients with epithelioid DMPM.

METHODS

Hematoxylin and eosin-stained slides of 232 patients with epithelioid DMPM (14 stage I, 54 stage II, 130 stage III, and 34 stage IV) from a single institution were reviewed. We classified the tumors into five subtypes, according to the predominant histological pattern: trabecular, tubulopapillary, micropapillary, solid, and pleomorphic (≥10% of tumor).

RESULTS

Median overall survival (OS) of all patients with epithelioid DMPM was 16.2 months. Patients with pleomorphic subtype (n = 34) had the worst median OS (8.1 months), followed by solid (n = 89, 13.7 months), micropapillary (n = 20, 15.8 months), tubulopapillary (n = 51, 17.9 months), and trabecular (n = 38, 24.9 months). The pleomorphic subtype was associated with lymphatic and vascular invasion (p < 0.001). The micropapillary subtype was associated with lymphatic invasion (p < 0.001). In univariate analyses, pleomorphic subtype was significantly associated with poor OS (p = 0.003). The pleomorphic subtype showed no significant difference on OS compared with biphasic and sarcomatoid DMPM. In a multivariate analysis, the pleomorphic subtype was an independent predictor of poor OS (p = 0.031). In patients who underwent R1 resection, pleomorphic subtype had the shortest median time to recurrence (13.7 months).

CONCLUSION

Our finding that the pleomorphic subtype is a predictor of aggressive behavior in epithelioid DMPM with no survival difference from biphasic or sarcomatoid DMPM suggests that it may be best regarded as a sarcomatoid pattern rather than a subtype of epithelioid DMPM.

Correlation between genomic alterations assessed by array comparative genomic hybridization, prognostically informative histologic subtype, stage, and patient survival in gastric cancer

It is difficult to evaluate the prognostic value of histologic criteria in gastric cancer because of the high variability of morphologic patterns. Recently, histologic subtypes of low, intermediate, or high malignant potential have been identified, providing the basis for a prognostically informative grading system. Because array comparative genomic hybridization systems allow systematic analysis of chromosome alterations, which may be prognostically and pathogenetically informative, we applied high-resolution genome-wide array comparative genomic hybridization to archival material from 81 gastric cancer cases followed for a median of 150 months after surgery. The DNA extracted from paraffin sections gave useful results in 49 tumors, 18 of which were of low-grade, 24 of intermediate, and 7 of high-grade histotypes. Based on the number of chromosome aberrations and the presence/absence of amplifications, 3 tumor clusters of increasing genomic lesion severity were constructed, which proved to correlate significantly with histologic grade and stage as well as with patient survival. Further investigation documented the lower number and severity of genomic alterations in tumors with microsatellite DNA instability and high CD8-rich lymphoid response; the close association of 8p23.1 amplification with cardial cancer; the frequent amplification of genes involved in cell renewal (CDC6, HER2, GRB7, IGFBP4) at 17q12-q21.1, with close histochemical correlation with HER2 membranous expression; and more sporadic amplification of chromosome regions harboring important oncogenes like MYC, KRAS, NRAS, CRKL, CCNE1, or ZNF217. We conclude that genome-wide array comparative genomic hybridization of gastric cancer contributes prognostically relevant information providing a genetic background for histologic grading.

Interrelationships between tumor proliferative activity, leucocyte and macrophage infiltration, systemic inflammatory response, and survival in patients selected for potentially curative resection for gastroesophageal cancer

BACKGROUND

A number of accepted criteria, including pathological tumor, node, metastasis system stage, lymph node metastasis, and tumor differentiation, predict survival in patients undergoing surgery for gastroesophageal cancer. We examined the interrelationships between standard clinicopathological factors, systemic and local inflammatory responses, tumor proliferative activity, and survival.

METHODS

The interrelationships between the systemic inflammatory response (Glasgow prognostic score, mGPS), standard clinicopathological factors, local inflammatory response (Klintrup criteria, macrophage infiltration), and tumor proliferative activity (Ki-67) were examined by immunohistochemistry in 100 patients (44 esophageal [19 squamous, 25 adenocarcinoma], 19 junctional, and 37 gastric cancers) selected for potentially curative resection.

RESULTS

The minimum follow-up was 59 months. On multivariate survival analysis, lymph node ratio (hazard ratio [HR] 1.63, 95% confidence interval [CI] 1.11-2.40, P < 0.05), tumor differentiation (HR 2.63, 95% CI 1.45-4.77, P = 0.001), mGPS (HR 3.91, 95% CI 1.96-8.11, P < 0.001), Klintrup score (HR 3.47, 95% CI 1.14-10.55, P < 0.05), and Ki-67 (HR 0.67, 95% CI 0.47-0.96, P < 0.05) were independently associated with cancer-specific survival. A higher lymph node ratio was associated with poor tumor differentiation (P < 0.05), low-grade Klintrup criteria (P < 0.005), and low tumor proliferative activity (P < 0.05).

CONCLUSION

Tumor proliferation rate and local and systemic inflammatory responses are important predictors of survival, albeit in a heterogeneous cohort of patients including esophageal, junctional, and gastric cancers. These scores may be combined with accepted tumor-based factors to improve prediction of outcome.

Inflammation in gastric adenocarcinoma of the cardia: how do EBV infection, Her2 amplification and cancer progression influence tumor-infiltrating lymphocytes?

Tumor-infiltrating lymphocytes (TILs) in gastric adenocarcinoma show a strong compartmentalization with high numbers of lymphocytes in the stroma and low intraepithelial lymphocyte counts. Our previous study has shown stromal regulatory T cells (Treg) to be associated with a beneficial outcome in intestinal type cancer of the cardia. We undertook the present study to further evaluate the immunogenic and inflammatory environment in intestinal-type gastric adenocarcinoma of the cardia. We assessed CXCR3 expression, Epstein-Barr virus (EBV) status, Her2/ERBB2 status and overexpression/amplification using tissue microarrays (immunohistochemistry and in situ hybridization) of 52 patients. The data were correlated to different TIL subset counts (CD3, CD8, GranzymeB, FoxP3 and CD20) and to infiltrating histiocytes (CD68) both in the tumor and the surrounding stromal tissue that were reported earlier. Her2/ERBB2 overexpression/amplification showed no correlation to tumor stage. Moreover, for the first time, we show here that Her2/ERBB2 overexpression/amplification has no correlation to overall or subset-specific TIL infiltration. EBV infection was seen in four cases and showed a strong association with intratumoral CD8(+) T cell infiltration as well as a moderate correlation to stromal CD8(+) T cell accumulation. Intratumoral CD8(+) T cell infiltration was significantly correlated to intratumoral FoxP3(+) Treg infiltration, and to a lesser extent, to stromal FoxP3(+) Treg counts. Stromal CXCR3(+) T cell infiltration showed an inverse correlation to T category. This highlights the importance of stromal immune processes for cancer growth and suggests a subversion of Th1 immunoresponse in cancer progression and underlines the important role of inflammation for early carcinogenesis.

Pathology of gastrointestinal disorders

Nonneoplastic and neoplastic proliferative lesions of endocrine cells of the gastrointestinal tract are detailed. A multistep continuum from hyperplasia, dysplasia to neoplasia is identified for histamine-producing enterochromaffin-like (ECL) cells of the gastric corpus. Most gastric neuroendocrine tumors (NETs) are silent and composed by ECL cells, the second most frequent neuroendocrine neoplasms being the high-grade neuroendocrine carcinoma (NEC). In the duodenum, preneoplastic lesions are similarly described for gastrin (G) and somatostatin (D) cells. G-cell NETs are the most frequent neuroendocrine tumors of the duodenum, either functioning or nonfunctioning, followed by D-cell NETs and gangliocytic paraganglioma (GCP). No systematic definition of nonneoplastic lesions exists for endocrine cells of the ileum, appendix, and colon-rectum. The most frequent ileal NETs are serotonin-producing enterochromaffin (EC)-cell NETs (classic carcinoid), associating with functional syndrome only in presence of liver metastases. Neoplasms are usually larger in the colon as compared with the small lesions observed in the rectum. High-grade NECs are observed in the colon and rectum-sigmoid, often associate with nonendocrine neoplastic components, and fare an aggressive course with poor outcome and short survival.