Evidence that gastric pit dysplasia-like atypia is a neoplastic precursor lesion

Global Progression Rates of Precursor Lesions for Gastric Cancer: A Systematic Review and Meta-Analysis

BACKGROUND & AIMS

Whether gastric cancer (GC) precursor lesions progress to invasive cancer at similar rates globally remains unknown. We conducted a systematic review and meta-analysis to determine the progression of precursor lesions to GC in countries with low versus medium/high incidence.

METHODS

We searched relevant databases for studies reporting the progression of endoscopically confirmed precursor lesions to GC. Studies were stratified by low (<6 per 100,000) or medium/high (≥6 per 100,000) GC incidence countries. Random-effects models were used to estimate the progression rates of atrophic gastritis (AG), intestinal metaplasia (IM), and dysplasia to GC per 1000 person-years.

RESULTS

Among the 5829 studies identified, 44 met our inclusion criteria. The global pooled estimates of the progression rate per 1000 person-years were 2.09 (95% confidence interval, 1.46-2.99), 2.89 (2.03-4.11), and 10.09 (5.23-19.49) for AG, IM, and dysplasia, respectively. The estimated progression rates per 1000 person-years for low versus medium/high GC incidence countries, respectively, were 0.97 (0.86-1.10) versus 2.47 (1.70-2.99) for AG (P < .01), 2.37 (1.43-3.92) versus 3.47 (2.13-5.65) for IM (P = .29), and 5.51 (2.92-10.39) versus 14.80 (5.87-37.28) for dysplasia (P = .08). There were no differences for progression of AG between groups when high-quality studies were compared.

CONCLUSIONS

Similar progression rates of IM and dysplasia were observed among low and medium/high GC incidence countries. This suggests that the potential benefits of surveillance for these lesions in low-risk regions may be comparable with those of population-wide interventions in high-risk regions. Further prospective studies are needed to confirm these findings and inform global screening and surveillance guidelines.

Pathology and Clinical Relevance of Gastric Epithelial Dysplasia

Gastric dysplasia is defined as an unequivocally neoplastic epithelium. Dysplastic lesions are characterized by cellular atypia reflective of abnormal differentiation and disorganized glandular architecture. The last few years have been marked by a refinement of the prognosis and risk of progression of gastric dysplasia and the recognition of novel morphologic patterns of dysplasia. Determination of the correct diagnosis and grade of dysplasia are critical steps since it will be predicting the risk of malignant transformation and help tailor appropriate surveillance strategy. This review describes the morphologic characteristics of conventional dysplasia and nonconventional gastric dysplasia that have been more recently characterized.

Gastric Intestinal Metaplasia: Real Culprit or Innocent Bystander as a Precancerous Condition for Gastric Cancer?

Gastric intestinal metaplasia (GIM), which denotes conversion of gastric mucosa into an intestinal phenotype, can occur in all regions of the stomach, including cardiac, fundic, and pyloric mucosa. Since the earliest description of GIM, its association with gastric cancer of the differentiated (intestinal) type has been a well-recognized concern. Many epidemiologic studies have confirmed GIM to be significantly associated with subsequent gastric cancer development. Helicobacter pylori, the principal etiologic factor for gastric cancer, plays the most important role in predisposing to GIM. Although the role of GIM in the stepwise progression model of gastric carcinogenesis (the so-called "Correa cascade") has come into question recently, we review the scientific evidence that strongly supports this long-standing model and propose a new progression model that builds on the Correa cascade. Eradication of H pylori is the most important method for preventing gastric cancer globally, but the effect of eradication on established GIM, is limited, if any. Endoscopic surveillance for GIM may, therefore, be necessary, especially when there is extensive corpus GIM. Recent advances in image-enhanced endoscopy with integrated artificial intelligence have facilitated the identification of GIM and neoplastic lesions, which will impact preventive strategies in the near future.

Gastric Intestinal Metaplasia in Mucosa Adjacent to Gastric Cancers Is Rarely Associated With the Aneuploidy That Is Characteristic of Gastric Dysplasia or Cancer

Most gastric cancers (GCs) are thought to develop via gastric intestinal metaplasia (GIM)-dysplasia-carcinoma pathway. Patients with extensive and/or incomplete GIM have been reported to have a higher risk of GC. GIM can also display dysplasia-like cytoarchitectural atypia limited to the bases of gastric pits without surface involvement. However, only a small proportion of GIM patients will develop gastric neoplasia, and it remains questionable if GIM is a direct precursor. A cohort of 82 GC patients with GIM who underwent gastrectomy were analyzed. DNA flow cytometry was performed on 109 GIM samples (including 88 predominantly complete GIM and 21 predominantly incomplete GIM subclassified based on morphology) obtained from adjacent mucosa of the 82 GCs. Only 2 (2%) of the 109 GIM samples demonstrated aneuploidy, both from 2 minority patients (Asian and Hispanic) with limited and complete GIM and no cytoarchitectural atypia. The remaining 107 GIM samples showed mild to focally moderate basal gland (metaplastic) atypia limited to the bases of gastric pits, but they all demonstrated normal DNA content regardless of anatomic location, histologic GIM subtype, or varying degrees of basal gland atypia. In conclusion, the vast majority of the GIM samples (98%) lack the aneuploidy that is characteristic of gastric dysplasia or cancer. This indicates that aneuploidy usually occurs after the development of gastric dysplasia rather than at the stage of GIM. The finding also suggests that the presence of GIM alone may not be sufficient to suggest an increased risk for GC and that the inclusion of other high-risk features (ie, extensive GIM, dysplasia, racial minorities, and/or family history of GC in a first-degree relative) and/or aneuploidy ought to play a role in the selection of GIM patients who may warrant endoscopic surveillance. Finally, GIM with mild to focally moderate basal gland atypia is likely to represent metaplastic atypia in most cases.

Non-conventional dysplasias of the tubular gut: a review and illustration of their histomorphological spectrum

The increasing use of gastrointestinal endoscopic procedures has led to the recognition by histopathologists of non-conventional (or special-type) dysplasias of the gastrointestinal tract. These lesions can be recognised in association with prevalent underlying gastrointestinal conditions, such as Barrett oesophagus, chronic atrophic gastritis, and inflammatory bowel disease. The diagnosis of these special types can be challenging, and their biological behaviours are not fully characterised. The aim of this review is to provide a global view of non-conventional dysplastic lesions observed in the various segments of the tubular gastrointestinal tract and describe their salient features. Furthermore, as the clinical implications of these various subtypes have not been broadly tested in practice and are not represented in most management guidelines, we offer guidance on the best management practices for these lesions.

Trop2 is upregulated in the transition to dysplasia in the metaplastic gastric mucosa

Intestinal-type gastric adenocarcinoma arises in a field of pre-existing metaplasia. While biomarkers of cancer and metaplasia have been identified, the definition of dysplastic transition as a critical point in the evolution of cancer has remained obscure. We have evaluated Trop2 as a putative marker of the transition from metaplasia to dysplasia in the stomach in multiple mouse models of metaplasia induction and progression. In addition, TROP2 expression was evaluated in human samples by immunostaining tissue microarrays for metaplasia, dysplasia, and gastric cancer. Dysplastic mouse organoids were evaluated in vitro following shRNA knockdown of Trop2 expression. In mouse models, no Trop2 was observed in the normal corpus and Trop2 was not induced in acute models of metaplasia induction with either L635 or DMP-777. In Mist1-Kras mice, Trop2 expression was not observed in metaplasia at 1 month after Kras induction, but was observed in dysplastic glands at 3-4 months after Kras induction. In human tissues, no Trop2 was observed in normal corpus mucosa or SPEM, but Trop2 expression was observed in incomplete intestinal metaplasia, with significantly less expression in complete intestinal metaplasia. Trop2 expression was observed in all dysplastic and 84% of gastric cancer lesions, although expression levels were variable. Dysplastic mouse organoids from Mist1-Kras mice expressed Trop2 strongly. Knockdown of Trop2 with shRNA markedly reduced organoid growth and budding behavior, and induced the upregulation of apical villin expression. We conclude that Trop2 is upregulated in the transition to dysplasia in the stomach and promotes dysplastic cell behaviors. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

LncRNA-RMRP promotes carcinogenesis by acting as a miR-206 sponge and is used as a novel biomarker for gastric cancer

Long noncoding RNAs (lncRNAs) play crucial roles in tumorigenesis. However, the mechanisms of most lncRNAs in cancers are largely unknown. Because the RNA component of mitochondrial RNA processing endoribonuclease (RMRP) is one of the dysregulated lncRNAs in gastric cancer, this study explored its molecular mechanisms in carcinogenesis. RMRP levels in 792 tissues, plasma and gastric juices from patients with various stages of gastric tumorigenesis were analyzed by quantitative reverse transcription-polymerase chain reaction. Overexpression and RNA interference were used to manipulate RMRP expression by RMRP expression vector and small interfering RNAs, respectively. Its mechanisms were evaluated by flow cytometry, real-time cell analysis, plate colony formation assays, and xenograft models. RMRP levels in tissue, plasma and gastric juices from patients with gastric cancer were significantly different from those from controls. Its levels were significantly associated with Borrmann type and metastasis. Plasma and gastric juice RMRP had higher sensitivity and specificity than commonly used markers (such as carcinoembryonic antigen and carbohydrate antigen 19-9). Knockdown of RMRP significantly inhibited cell proliferation in vitro and in vivo, whereas overexpression of RMRP promoted cell growth. Acting as a miR-206 sponge, RMRP modulated cell cycle by regulating Cyclin D2 expression. RMRP plays a crucial role in gastric cancer occurrence and can be used as a novel biomarker for gastric cancer.

Species-specific role of gene-adjacent retroelements in human and mouse gastric carcinogenesis

Helicobacter pylori (HP) infection promotes the recruitment of bone marrow stem cells into chronic gastritis lesions. Some of these marrow stem cells can differentiate into gastric epithelial cells and neoplastic cells. We propose that HP-associated methylation could stabilize trans-differentiation of marrow-derived stem cells and that an unstable methylation status is associated with a risk of gastric cancer. Pathobiologic behavior of experimental mouse gastric cancer is mild compared to invasive and metastatic human gastric cancer. Differences in epigenetic stabilization of adult cell phenotypes between humans and mice could provide a foundation to explore the development of invasive and metastatic gastric cancer. Retroelements are highly repetitive sequences that play an essential role in the generation of species diversity. In this review, we analyzed retroelements adjacent to human and mouse housekeeping genes and proposed a possible epigenetic mechanism for HP-associated carcinogenesis.

Occurrence of metachronous or synchronous lesions after endoscopic treatment of gastric epithelia dysplasia- impact of histologic features of background mucosa

AIMS

Endoscopic resection is a safe and effective method to treat gastric epithelia dysplasia (GED). However, the development of metachronous and synchronous lesions after treatment has become a major concern. In this study, we investigated clinicopathologic features of 105 GED lesions from endoscopic resections between January 2008 and December 2009. Our goal is to find histologic factors that predict synchronous and metachronous lesions after ESD treatment. We assessed the degree of intestinal metaplasia (IM) and atrophy, type of IM, presence of gastritis cystica profunda, and crypt dysplasia in the adjacent mucosa.

METHODS AND RESULTS

We divided 105 GED lesions into three groups: a single group without metachronous or synchronous GED or adenocarcinoma (n=35); a multiple synchronous group (n=30, group with synchronous occurrence of GED or adenocarcinoma after treatment); and a multiple metachronous group (n=40, group with metachronous occurrence of GED or adenocarcinoma after treatment). The multiple metachronous and synchronous groups showed larger sizes (p=0.003) and higher grades (p=0.021) as compared with the single group. Furthermore, marked IM and atrophy in adjacent mucosa were more easily seen in the multiple metachronous and synchronous groups as compared with the single group (p<0.0001). Interestingly, the presence of incomplete type of IM (p=0.025) and crypt dysplasia (p<0.0001) in background mucosa was associated with occurrence of metachronous and synchronous lesions following endoscopic resection of GED.

CONCLUSIONS

The histological features of background mucosa, such as intestinal metaplasia, atrophy, and crypt dysplasia could be used as indicators of occurrence of metachronous and synchronous lesions after endoscopic treatment of GED.

Negative pathology after endoscopic resection of gastric epithelial neoplasms: importance of pit dysplasia

BACKGROUND/AIMS

Endoscopic resection (ER) is a well-established treatment modality for gastric epithelial neoplasm. However, there is a discrepancy between forceps biopsy and ER specimen pathology, including a negative pathologic diagnosis (NPD) after ER. It has been suggested that pit dysplasia (PD) is a subtype of gastric dysplasia, and the aim of this study was to assess the significance of PD in cases with NPD after ER for early gastric neoplasms.

METHODS

After ER, 29 NPD lesions that had an associated pretreatment forceps biopsy specimen, were correctly targeted during ER, and had no cautery artifact on the resected specimen were included in this study.

RESULTS

Sixteen lesions showed PD and 13 had no neoplastic pathology. The initial pretreatment forceps biopsy diagnoses of 29 NPD lesions were low-grade dysplasia (LGD) in 17 lesions, high-grade dysplasia (HGD) in seven lesions, and adenocarcinoma in five lesions, which after review were revised to PD in 19 lesions, LGD in four lesions, adenocarcinoma in two lesions, and no neoplastic pathology in four lesions. Overall, nine lesions (31%) were small enough to be removed by forceps biopsy, four NPD lesions (14%) were initially misinterpreted as neoplastic lesions, and 16 PD lesions (55%) were misinterpreted as NPD lesions on ER slides.

CONCLUSIONS

Approximately half of the lesions initially diagnosed as LGD or HGD were subsequently classified as PD. Therefore, including PD as a subtype of gastric dysplasia could reduce the diagnostic discrepancy between initial forceps biopsy and ER specimens.

Barrett's Esophagus: A Comprehensive and Contemporary Review for Pathologists

This review provides a summary of our current understanding of, and the controversies surrounding, the diagnosis, pathogenesis, histopathology, and molecular biology of Barrett's esophagus (BE) and associated neoplasia. BE is defined as columnar metaplasia of the esophagus. There is worldwide controversy regarding the diagnostic criteria of BE, mainly with regard to the requirement to histologically identify goblet cells in biopsies. Patients with BE are at increased risk for adenocarcinoma, which develops in a metaplasia-dysplasia-carcinoma sequence. Surveillance of patients with BE relies heavily on the presence and grade of dysplasia. However, there are significant pathologic limitations and diagnostic variability in evaluating dysplasia, particularly with regard to the more recently recognized unconventional variants. Identification of non-morphology-based biomarkers may help risk stratification of BE patients, and this is a subject of ongoing research. Because of recent achievements in endoscopic therapy, there has been a major shift in the treatment of BE patients with dysplasia or intramucosal cancer away from esophagectomy and toward endoscopic mucosal resection and ablation. The pathologic issues related to treatment and its complications are also discussed in this review article.

DNA Methylation as Surrogate Marker For Gastric Cancer

Stomach cancer remains, stubbornly, highly prevalent in East Asia. Still, stomach cancer has few biomarkers by which it can be predicted. Helicobacter pylori infection, a known carcinogen of stomach cancer, usually goes undetected prior to cancer diagnosis, due to the poor mucosal environments that its related gastric atrophy causes. We propose, herein, an endoscopic-biopsy-based cancer-predicting DNA methylation marker. We semi-quantitatively examined the methylation-variable sites near the CpG-island margins by radioisotope-labeling methylation-specific polymerase chain reaction in association with H. pylori, which increases age-related over-methylation in CpG islands of gastric mucosa. These age-related methylation patterns of the transitional-CpG sites are proposed as useful surrogate markers for stomach cancer. It would be helpful for setting the optimal screening interval for high-risk subjects as well as for estimating the prognosis and the predictability for recurrence of early gastric cancer in patients having undergone endoscopic submucosal dissection. New screening-interval guidelines for gastric cancer should be suggested considering individual risk based on age, severity of atrophy, H. pylori status, and DNA methylation pattern.

Incidence of gastric cancer among patients with gastric precancerous lesions: observational cohort study in a low risk Western population

OBJECTIVE

To accurately measure the incidence of gastric cancer among patients with gastric precancerous lesions, and to quantify the excess incidence in comparison with people with normal mucosa on endoscopy and a general population.

DESIGN

Population based cohort study.

SETTING

Population of Sweden using data from its national disease registers.

PARTICIPANTS

405,172 patients who had gastric biopsy samples taken for non-malignant indications between 1979 and 2011.

MAIN OUTCOME MEASURES

Incidence of gastric cancer, reported separately for patients with different mucosal changes in biopsy samples. Standardised incidence ratios provided estimation of the relative risk, using the general Swedish population as reference; and hazard ratios were derived from Cox regression modelling for internal comparisons with patients with normal gastric mucosa.

RESULTS

After excluding the first two years of follow-up, 1599 cases of gastric cancer were identified. The annual crude incidence of gastric cancer was 20 × 10(-5) for those in the normal mucosa group (standardised incidence ratio 1.0), 42 × 10(-5) for those with minor changes (1.5), 59 × 10(-5) for the gastritis group (1.8), 100 × 10(-5) for the atrophic gastritis group (2.8), 129 × 10(-5) for the intestinal metaplasia group (3.4), and 263 × 10(-5) for the dysplasia group (6.5). Cox regression modelling confirmed that excess risks increased monotonically with progressive severity of gastric lesions, with the highest hazard ratio of 10.9 (dysplasia versus normal mucosa, 95% confidence interval 7.7 to 15.4). The increased incidence was stable throughout the follow-up period, and the gaps between cumulative incidence curves grew continuously.

CONCLUSIONS

Among patients who undergo gastroscopy with biopsy for clinical indications, approximately 1 in 256 with normal mucosa, 1 in 85 with gastritis, 1 in 50 with atrophic gastritis, 1 in 39 with intestinal metaplasia, and 1 in 19 with dysplasia will develop gastric cancer within 20 years. These numbers, along with cost-benefit analyses, should guide future surveillance policies for these particular patient groups.

Low expression of lncRNA-HMlincRNA717 in human gastric cancer and its clinical significances

Long noncoding RNAs (lncRNAs) have been gradually confirmed to be tumor-associated biological molecules in recent years. However, the clinical significances of most lncRNAs in the screening of gastric cancer are largely unknown. Based on our lncRNA array results, in this study, we explored the potential relationship between HMlincRNA717 expression levels and clinicopathologic factors of gastric cancer. A total of 313 samples were collected from two cancer centers, and then HMlincRNA717 level in human gastric cancer tissues and gastric cell lines was measured by real-time reverse transcription-polymerase chain reaction. Then, HMlincRNA717 levels at multiple stages of gastric tumorigenesis were investigated and the potential association between it levels, and clinicopathological features were analyzed. The expression levels of HMlincRNA717 in five gastric cancer cell lines, AGS, BGC-823, HGC-27, MGC-803, and SGC-7901, were significantly downregulated than those in normal gastric mucosal epithelial cell line GES-1. It was not only downregulated in 62.6 % (67/107) gastric cancer tissues compared with the paired adjacent normal tissues but also in gastric precancerous lesions. More importantly, our results indicated that HMlincRNA717 expression levels were correlated with cancer distal metastasis (P = 0.034), venous invasion (P = 0.029), and nervous invasion (P = 0.024). Our data suggested that lncRNA-HMlincRNA717 may play crucial roles during cancer occurrence and progression and may be a new potential biomarker of early gastric cancer.