Gastric preneoplastic lesions and epithelial dysplasia

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.

Identifying the pre-malignant stomach: from guidelines to practice

Gastric adenocarcinoma develops after stepwise progression from normal mucosa through to adenocarcinoma most commonly after being triggered by Helicobacter pylori (H. pylori) infection. As disease is often diagnosed late, the prognosis for gastric adenocarcinoma is poor. Identifying pre-malignant mucosal lesions such as atrophic gastritis, intestinal metaplasia and dysplasia is one strategy adopted by clinicians to reduce cancer related mortality. Surveillance of high-risk individuals and endoscopic resection of dysplastic lesions is recommended by international and UK guidelines. The early detection and endoscopic management reduce the need for invasive surgery. The advancement of image enhanced endoscopy technology, endoscopic training, risk stratification and histological assessment has proven pivotal to the management of pre-malignant lesions. In this review we outline the development of a high-risk stomach, endoscopic assessment and review practical guidelines on identifying pre-malignant gastric mucosa.

Morphological and histological abnormalities of the neotropical toad, Rhinella arenarum (Anura: Bufonidae) larvae exposed to dexamethasone

Dexamethasone (DEX) is a glucocorticoid highly effective as an anti-inflammatory, immunosuppressant and decongestant drug. In the present study, a preliminary acute toxicity test was assayed in order to determinate DEX median-lethal, lowest-observed-effect and the no-observed-effect concentrations (LC₅₀, LOEC and NOEC, respectively) on the common toad embryos (Rhinella arenarum). Also, morphological and histological abnormalities from five body larval regions, liver melanomacrophages (MM) and glutathione S-transferase (GST) activity were evaluated in the toad larvae to characterize the chronic sublethal effects of DEX (1-1,000 µg L^-L). Results of the acute test showed that the LC₅₀ of DEX at 96 h of exposure for the toad embryos (GS 18-20) was 10.720 mg L^-g, and the LOEC was 1 µg L^-g. In the chronic assay, the larval development and body length were significantly affected. DEX exposition also induced teratogenic effects. Most frequent external abnormalities observed in DEX-treated larvae included abdominal edema and swollen body, abnormal gut coiling and visceral congestion. Intestinal dysplasia was recurrent in cross-section of all DEX-treated larvae. Neural, conjunctive and renal epithelial cells were also affected. Significant increase in liver MM number and size, and GST activity levels were also registered in DEX treatments with respect to controls. The evaluation of a variety of biomarkers provided clear evidence of toad larvae sensitivity to DEX, and the ecotoxicological risk of these pharmaceuticals, commonly found in different water bodies worldwide on aquatic animals.

Wnt5a Signaling in Gastric Cancer

Gastric cancer remains an important health challenge, accounting for a significant number of cancer-related deaths worldwide. Therefore, a deeper understanding of the molecular mechanisms involved in gastric cancer establishment and progression is highly desirable. The Wnt pathway plays a fundamental role in development, homeostasis, and disease, and abnormal Wnt signaling is commonly observed in several cancer types. Wnt5a, a ligand that activates the non-canonical branch of the Wnt pathway, can play a role as a tumor suppressor or by promoting cancer cell invasion and migration, although the molecular mechanisms explaining these roles have not been fully elucidated. Wnt5a is increased in gastric cancer samples; however, most gastric cancer cell lines seem to exhibit little expression of this ligand, thus raising the question about the source of this ligand in vivo. This review summarizes available research about Wnt5a expression and signaling in gastric cancer. In gastric cancer, Wnt5a promotes invasion and migration by modulating integrin adhesion turnover. Disheveled, a scaffolding protein with crucial roles in Wnt signaling, mediates the adhesion-related effects of Wnt5a in gastric cancer cells, and several studies provide growing support for a model whereby Disheveled-interacting proteins mediates Wnt5a signaling to modulate cytoskeleton dynamics. However, Wnt5a might induce other effects in gastric cancer cells, such as cell survival and induction of gene expression. On the other hand, the available evidence suggests that Wnt5a might be expressed by cells residing in the tumor microenvironment, where feedback mechanisms sustaining Wnt5a secretion and signaling might be established. This review analyzes the possible functions of Wnt5a in this pathological context and discusses potential links to mechanosensing and YAP/TAZ signaling.

Use of DNA flow cytometry in the diagnosis, risk stratification, and management of gastric epithelial dysplasia

The natural history of gastric epithelial dysplasia and the consequential surveillance strategies are not well defined in the West. To date, the diagnosis relies on morphology, and no reliable adjunct methods, either immunohistochemical or molecular, have reproducibly been able to confirm the diagnosis and/or risk stratify gastric epithelial dysplasia. Yet, such a tool would be useful in confirming the diagnosis, and developing objective and rational surveillance guidelines. DNA flow cytometry was performed using formalin-fixed paraffin-embedded gastric tissue from 23 cases of high-grade dysplasia and 38 cases of low-grade dysplasia. Twenty-four benign background mucosal samples from the same cohort (20 biopsies and 4 surgical resections from 16 low- and 8 high-grade dysplasia cases) were utilized as controls. The presence of DNA content abnormality (aneuploidy or elevated 4N fraction) correlated with increasing levels of dysplasia, as DNA content abnormality was detected in 18 (78%) of 23 high-grade dysplasia, 5 (13%) of 38 low-grade dysplasia, and none of 24 non-dysplastic samples. 1 and 4-year detection rates of high-grade dysplasia or gastric adenocarcinoma in low-grade dysplasia patients with DNA content abnormality were 80% (p = 0.003) and 100% (p = 0.005), respectively, whereas patients with low-grade dysplasia but with normal DNA content had 1, 4, and 12-year detection rates of 23, 32, and 54%, respectively. The univariate hazard ratio (HR) for subsequent detection of high-grade dysplasia or gastric adenocarcinoma in low-grade dysplasia patients with DNA content abnormality was 6.9 (p = 0.001). Older patients (HR = 1.1, p = 0.005) and those with familial adenomatous polyposis (HR = 9.7, p = 0.029) also had an increased risk for developing high-grade dysplasia or gastric adenocarcinoma in the univariate analysis, but only DNA content abnormality demonstrated a significantly elevated HR of 5.9 in the multivariate analysis (p = 0.005). While older age showed a minimally elevated risk (HR = 1.1, p = 0.013), no other potential risk factors, including male gender, ethnicity, polypoid endoscopic appearance, Helicobacter pylori infection, and intestinal metaplasia, were significantly associated with subsequent detection of high-grade dysplasia or gastric adenocarcinoma in the multivariate analysis. Among the 18 high-grade dysplasia cases with DNA content abnormality, 13 cases (72%) developed gastric adenocarcinoma within a mean follow-up time of 9 months, conferring a HR of 2.5; however, this did not reach statistical significance. In conclusion, the presence of DNA content abnormality can identify a subset of low-grade dysplasia patients who are at increased risk for subsequent detection of high-grade dysplasia or gastric adenocarcinoma. It can also provide confirmatory evidence to a morphologic impression or suspicion of high-grade dysplasia. The majority of gastric epithelial dysplasia patients with DNA content abnormality developed high-grade dysplasia or gastric adenocarcinoma within a year and thus may benefit from more thorough and rigorous endoscopic surveillance.

The chronological sequence of somatic mutations in early gastric carcinogenesis inferred from multiregion sequencing of gastric adenomas

Mutation profiles and intratumoral heterogeneity are not well understood for benign gastric adenomas, some of which progress into malignant gastric adenocarcinomas. In this study, we performed whole-exome sequencing of three microsatellite stable (MSS) and two microsatellite instability-high (MSI-H) gastric adenomas with three regional tumor biopsies per case. We observed that the mutation abundance of benign gastric adenomas was comparable to those of gastric adenocarcinomas, suggesting that the mutational makeup for gastric carcinogenesis may already be achieved in benign adenomas. The extent of intratumoral heterogeneity was more substantial for MSS genomes in that only 1% - 14% of somatic mutations were common across the regional biopsies or 'public', while 50% - 94% of mutations were public in MSI-H gastric adenomas. We observed biallelic, loss-of-functional events of APC with truncating mutations and/or 5q losses for all cases, mostly as public events. All MSS gastric adenomas also harbored ARID2 truncating mutations, often as multiple, region-specific ones indicative of convergent evolution. Hotspot missense mutations on known cancer genes such as ERBB2 and KRAS were largely observed as region-specific aberrations. These findings suggest that biallelic functional APC inactivation initiates the gastric carcinogenesis and is followed by mutations of histone modifiers and then activation of known cancer-related genes. As the first exome-wide multi-region mutational profiling of gastric adenomas, our study provides clues on the chronological sequence of somatic mutations and their clonal architectures in early gastric carcinogenesis.

Differences in Prevalence of Lymphovascular Invasion among Early Gastric Cancers between Korea and Japan

BACKGROUND/AIMS

The presence of invasion is a diagnostic criterion of early gastric cancer (EGC) in Korea, whereas diagnosis in Japan is based on enlarged nuclei and prominent nucleoli. Moreover, the depth of invasion is the location of cancer cell infiltration in Korea, whereas it is the location of lymphovascular invasion (LVI) or cancer cell infiltration in Japan. We evaluated the characteristics of EGC with LVI to uncover the effects of different diagnostic criteria.

METHODS

Consecutive T1-stage EGC patients who underwent complete resection were included after endoscopic or surgical resection. The presence of LVI was evaluated.

RESULTS

LVI was present in 112 of 1,089 T1-stage EGC patients. LVI was associated with depth of invasion (p<0.001) and age (p=0.017). The prevalence of LVI in mucosal cancer was significantly higher in Korea (p<0.001), whereas that of submucosal cancer was higher in Japan (p=0.024). For mucosal EGC types, LVI was positively correlated with diagnostic criteria applied in Korea (p=0.017). For submucosal EGC types, LVI was positively correlated with Japanese criteria (p=0.001) and old age (p=0.045).

CONCLUSIONS

The higher prevalence of LVI for mucosal EGC in Korea and for submucosal EGC in Japan indicates that different diagnostic criteria should be considered when reading publications from other countries.

Optimal management of biopsy-proven low-grade gastric dysplasia

Gastric adenocarcinoma generally culminates via the inflammation-metaplasia-dysplasia-carcinoma sequence progression. The prevalence of gastric adenomas shows marked geographic variation. Recently, the rate of diagnosis of low-grade dysplasia (LGD) has increased due to increased use of upper endoscopy. Many investigators have reported that gastric high-grade dysplasia has high potential for malignancy and should be removed; however, the treatment for gastric LGD remains controversial. Although the risk of LGD progression to invasive carcinoma has been reported to be inconsistent, progression has been observed during follow-up. Additionally, the rate of upgraded diagnosis in biopsy-proven LGD is high. Therefore, endoscopic resection (ER) may be useful in the treatment and diagnosis of LGD, especially if lesions are found to have risk factors for upgraded histology after ER, such as large size, surface erythema or depressed morphology. Fatal complications in endoscopic submucosal dissection (ESD) are extremely low and its therapeutic and diagnostic outcomes are excellent. Therefore, ESD should be applied preferentially instead of endoscopic mucosal resection.

Morphology and natural history of familial adenomatous polyposis-associated dysplastic fundic gland polyps

AIMS

Most patients with familial adenomatous polyposis (FAP) develop gastric fundic gland polyps, with many displaying low-grade dysplasia. This study evaluates the natural history and morphological phenotype of dysplasia in FAP-associated fundic gland polyps.

METHODS AND RESULTS

Patients with FAP and dysplastic fundic gland polyps (n = 24) were identified. Twenty-two of 24 FAP-associated dysplastic fundic gland polyps showed a gastric phenotype and two had mixed phenotype. During a mean 6.1-year follow-up (range 0.8-12.6 years) and 5.7 endoscopies (range 2-22), one patient (4%) was diagnosed with a fundic gland polyp with high-grade dysplasia, while 23 patients (96%) in this cohort had either no dysplasia or persistent low-grade dysplasia. Contemporary patients with sporadic fundic gland polyps with low-grade dyplasia had similar morphology and outcomes to the FAP-associated fundic gland polyp cohort. Dysplasia in fundic gland polyps (FAP-associated and sporadic) was associated less frequently with intestinal phenotype, high-grade dysplasia and the finding of concurrent or subsequent carcinoma compared to contemporary patients with sporadic gastric dysplasia not occurring in fundic gland polyps.

CONCLUSIONS

This cohort of patients with FAP-associated dysplastic fundic gland polyps rarely developed high-grade dysplasia and gastric adenocarcinoma was absent.

Is lesion size an independent indication for endoscopic resection of biopsy-proven low-grade gastric dysplasia?

BACKGROUND/AIM

The standard treatment for patients with gastric low-grade dysplasia (LGD) remains controversial, even though diagnosis of LGD is increasingly common as esophagogastrodeuodenoscopy becomes more available. The aim of this study was to identify a lesion size cut-off as an indication for endoscopic resection (ER) for patients with LGD.

RESULTS

We retrospectively reviewed 285 lesions initially diagnosed as LGD by endoscopic forceps biopsies (EFB) from 2007 to 2010 in Kyung Hee University Hospital, Seoul, Korea. All patients underwent ER. A total of 285 lesions from 257 patients were assessed. After ER, 239 LGD (83.9 %) showed histological concordance and the remaining 46 (16.1 %) cases revealed an upgraded histology [22 high-grade dysplasia (7.7 %), and 24 differentiated adenocarcinoma (8.4 %)]. Univariate analyses demonstrated that lesion size, erythema, depression, and erosion were significant predictors of upgraded LGD (P < 0.001). Multivariate analysis showed that a lesion size ≥2 cm, erythema, and a depressed-type lesion were independent predictors of upgraded histology (P = 0.014, odds ratio 3.27, 95 % confidence interval 1.28-8.39).

CONCLUSIONS

Our data suggest that a substantial number of LGD diagnoses based on EFB were not representative of the entire lesion. We recommend ER if gastric LGD has at least one of the following risk factors: surface erythema and a depressed type regardless of size, or ≥2 cm size regardless of abnormal surface configuration.

Endoscopic tri-modal imaging improves detection of gastric intestinal metaplasia among a high-risk patient population in Singapore

BACKGROUND

Detection of pre-neoplastic gastric mucosal changes and early gastric cancer (EGC) by white-light endoscopy (WLE) is often difficult. In this study we investigated whether combined autofluorescence imaging (AFI) and narrow band imaging (NBI) can improve detection of pre-neoplastic lesions and early gastric cancer in high-risk patients.

PATIENTS AND METHODS

Chinese patients who were 50-years-old or above with dyspepsia were examined by both high-resolution WLE and combined AFI followed by NBI (AFI-NBI), consecutively in a prospective randomized cross-over setting, by two experienced endoscopists. The primary outcome was diagnostic ability of the two methods for patients with pre-neoplastic lesions such as intestinal metaplasia (IM) and mucosal atrophy.

RESULTS

Sixty-five patients were recruited. One patient with large advanced gastric cancer was found and excluded from the analysis. Among the remaining 64 patients, 38 (59%) had IM; of these, 26 (68%) were correctly identified by AFI-NBI (sensitivity 68%, specificity 23%) and only 13 (34%) by WLE (sensitivity 34%, specificity 65%). AFI-NBI detected more patients with IM than did WLE (p=0.011). Thirty-one patients (48%) had mucosal atrophy. Ten patients (32%) were identified by AFI-NBI (sensitivity 32%, specificity 79%) and four patients (13%) by WLE (sensitivity 13%, specificity 88%) (p=0.100). No dysplasia or EGC was found.

CONCLUSION

AFI-NBI identified significantly more patients with IM than did WLE. Our result warrants further studies to define the role of combined AFI-NBI endoscopy for detection of precancerous conditions.

Management of gastric polyps: an endoscopy-based approach

The endoscopic finding of a gastric polyp and the histopathologic report that follows may leave clinicians with questions that have not been addressed in formal guidelines: do all polyps need to be excised, or can they just be sampled for biopsy? If so, which ones and how many should be sampled? What follow-up evaluation is needed, if any? This review relies on the existing literature and our collective experience to provide practical answers to these questions. Fundic gland polyps, now the most frequent gastric polyps in Western countries because of widespread use of proton pump inhibitors, and hyperplastic polyps, the second most common polyps notable for their association with gastritis and their low but important potential for harboring dysplastic or neoplastic foci, are discussed in greater detail. Adenomas have had their name changed to raised intraepithelial neoplasia and are decreasing in parallel with Helicobacter pylori infection; however, they do retain their importance as harbingers of gastric cancer, particularly in East Asia. Gastrointestinal stromal tumors have low incidence and no known associations, but their malignant potential is high; early diagnosis and proper management are crucial. Although rare and benign, inflammatory fibroid polyps need to recognized, particularly by pathologists, to avoid misdiagnosis. Gastric neuroendocrine tumors (carcinoids) are important because of their association with either atrophic gastritis or the multiple endocrine neoplasia syndromes; those that do not arise in these backgrounds have high malignant potential and require aggressive management. The review concludes with some practical suggestions on how to approach gastric polyps detected at endoscopy.

[Clinical aspects of premalignant lesions of the upper gastrointestinal tract]

A variety of somatic genetic and epigenetic aberrations are discussed in the multistep carcinogenesis of tumors of the upper gastrointestinal tract but specific genetic changes are still unknown. Primary prevention of cancer is important and includes the control of causal endo- and exogenous factors. Screening endoscopies to detect premalignant lesions or early carcinoma cannot be recommended in the Western world. The incidence of preinvasive neoplasia, above all the high-grade intraepithelial neoplasia, in Barrett's esophagus or stomach is as low as 4.0 or 0.6%, respectively. Secondary prevention of cancer after changes of the mucosa should be performed by endoscopic diagnosis and treatment performing biopsies or resection of the lesion. After histological diagnosis of a high-grade intraepithelial neoplasia, complete resection of these lesions including complete ablation of Barrett's mucosa should be carried out. On the basis of an exact pathological report, close cooperation between endoscopist and surgeon seems to be necessary to find out the best individual therapy with curative intent.

[Pathology and pathobiology of the gastric carcinoma]

Recent epidemiological studies in Serbia revealed that gastric carcinoma is the third and the fifth main cause of cancer morbidity in men and women, respectively. Despite the declining incidence of gastric cancer, it remains the second most common cause of cancer-related deaths as it is worldwide. A well-defined carcinogenic inflammation-metaplasia-dysplasia-cancer sequence typically precedes the development of most gastric adenocarcinomas. Alterations such as gastric mucosal atrophy and intestinal metaplasia are merely markers of increased risk, while gastric epithelial dysplasia (GED) represent a direct precursor of cancer. DNA damage and increased mucosal proliferation secondary to H pylori infection, combined with a suitable host susceptibility phenotype (eg, genetic polymorphisms in interleukin IL-1B, IL-1RN, and tumor necrosis factor a TNF-alpha genes), are important factors in this progression pathway. However, only a small minority of patients infected with H. pylori eventually develops gastric cancer, and eradication of H pylori in these patients does not seem to eliminate the risk of cancer completely. It has been shown that atrophy may be a better indicator of risk of cancer than intestinal metaplasia, and remains to be validated in routine clinical practice according to recent proposal for new quantitative methods. It is often associated with pseudopyloric gland metaplasia in the gastric corpus mucosa, which expresses a type of trefoil peptide, the spasmolytic polypeptide (termed spasmolytic polypeptide-expressing metaplasia or SPEM) and has been shown to be linked more closely to gastric cancer than intestinal metaplasia. Better histological characterization of adenomatous (or type I), hyperplastic (foveolar or type II) and tubule-neck (mucocellular or type III) GED, two-tiered grading system (low and high grade dysplasia) as well as the introduction of Padova and Vienna international classifications of dysplasia seem to be more helpful in GED surveillance and comparative studies. A combination of histopathological features, serum markers such as pepsinogen I, and molecular tests that analyze host susceptibility polymorphisms and bacterial virulence factors, may allow development of strategies for early detection of cancer in the future. At present, pathobiology of gastric cancerogenesis is far from known, despite the progressive knowledge on predisposing environmental conditions and genetic and epigenetic abnormalities, including tumour suppressor genes, oncogenes, microsatellite instability and hypermethylation or the significance of E-cadherin mutational status association with hereditary diffuse gastric cancer syndrome. Recent evidence regarding the importance of several histopathologically derived prognostic factors, such as resection margin status and lymph node metastases and their implications have also been discussed. We aim to review these aspects, with special relevance to gastric cancer specimen reporting.

Gastric cancer: an infectious disease

The role of infectious agents and chronic inflammation in carcinogenesis is being increasingly recognized. It has been estimated that about 18% of cancers are directly linked to infections, particularly gastric adenocarcinoma (Helicobacter pylori), cervical carcinoma (human papilloma viruses), and hepatocarcinoma (hepatitis B and C viruses). Multiple clinical trials of COX-2 inhibitors and other antiinflammatory agents have shown a beneficial effect on the development of diverse tumors, such as those of the colon, stomach, prostate, and breast. However, their mechanism of action is not completely understood and may differ among the infectious agents and tumor types. Because gastric adenocarcinomas account for more than 90% of all gastric malignancies, this review focuses on adenocarcinomas.

Loss of cell polarity protein Lgl2 in foveolar-type gastric dysplasia: correlation with expression of the apical marker aPKC-zeta

Recognition of gastric epithelial dysplasia, although a key to cancer prevention, can be challenging. In this study, we evaluated whether Lgl2 can serve as a marker of gastric foveolar-type dysplasia. Since atypical protein kinase C (aPKC) is a partner of Lgl2 in the control of apical-basal polarity we also investigated whether aPKC-zeta can compliment Lgl2 as a marker of dysplasia. Routinely processed specimens included 64 normal mucosa, 35 reactive gastropathies, 31 chronic gastritides, 65 gastric dysplasias (25 foveolar; 40 adenomatous), and 34 gastric adenocarcinomas. Twenty (80%) foveolar-type dysplasias showed absence of Lgl2 immunoreactivity, while normal basolateral expression of Lgl2 was consistently seen in normal gastric epithelium (n=20) and chronic gastritis (n=22; p<0.00001). Loss of Lgl2 was similar in the groups with low-grade and high-grade foveolar-type dysplasia, 79% and 83%, respectively. Linear apical anti-aPKC-zeta immunoreactivity was consistently present in the normal epithelium and was preserved in 91% of reactive gastropathies and 87% of chronic gastritides. In contrast, loss of apical aPKC-zeta staining was observed in 47% and 65% of low-grade dysplasias of foveolar and adenomatous types, respectively (p<0.005) and in nonsignificantly higher percentage of high-grade dysplasias. Apical aPKC-zeta staining was lost in 97% of gastric adenocarcinomas. Our data suggest a role of Lgl2 immunohistochemistry as an adjunct in the diagnosis of foveolar-type gastric dysplasia. aPKC-zeta had moderate sensitivity as a marker of gastric dysplasia and additional studies are needed to establish its role in the diagnosis of dysplasia.

The transcription factor MIST1 is a novel human gastric chief cell marker whose expression is lost in metaplasia, dysplasia, and carcinoma

The lack of reliable molecular markers for normal differentiated epithelial cells limits understanding of human gastric carcinogenesis. Recognized precursor lesions for gastric adenocarcinoma are intestinal metaplasia and spasmolytic polypeptide expressing metaplasia (SPEM), defined here by ectopic CDX2 and TFF2 expression, respectively. In mice, expression of the bHLH transcription factor MIST1, normally restricted to mature chief cells, is down-regulated as chief cells undergo experimentally induced metaplasia. Here, we show MIST1 expression is also a specific marker of human chief cells. SPEM, with and without MIST1, is present in human lesions and, akin to murine data, likely represents transitional (TFF2(+)/MIST1(+) = "hybrid"-SPEM) and established (TFF2(+)/MIST1(-) = SPEM) stages. Co-visualization of MIST1 and CDX2 shows similar progressive loss of MIST1 with a transitional, CDX2(+)/MIST1(-) hybrid-intestinal metaplasia stage. Interinstitutional analysis and comparison of findings in tissue microarrays, resection specimens, and biopsies (n > 400 samples), comprising the entire spectrum of recognized stages of gastric carcinogenesis, confirm MIST1 expression is restricted to the chief cell compartment in normal oxyntic mucosa, rare in established metaplastic lesions, and lost in intraepithelial neoplasia/dysplasia and carcinoma of various types with the exception of rare chief cell carcinoma ( approximately 1%). Our findings implicate MIST1 as a reliable marker of mature, healthy chief cells, and we provide the first evidence that metaplasia in humans arises at least in part from the chief cell lineage.

Neoplasia without dysplasia: lessons from Barrett esophagus and other tubal gut neoplasms

CONTEXT

Classic pathology teaching emphasizes that neoplastic lesions of the gastrointestinal tract are characterized by architectural and cytologic abnormalities that distinguish it from normal tissue. Recent studies suggest that many important-and in some cases clonal-molecular abnormalities that lead to dysregulation of cell proliferation and differentiation (neoplasia) occur before morphologic expression of dysplasia.

OBJECTIVE

To summarize the biologic and pathologic features of preneoplastic conditions of the tubal gut that reveal evidence of neoplastic alteration, but without the traditional morphologic features of dysplasia, in order to provide guidance on how to identify these lesions. Particular attention is given to Barrett esophagus, a chronic inflammatory condition in which early molecular and morphologic events that drive carcinogenesis are best understood.

DATA SOURCES

Selected references and abstracts were obtained by a PubMed (US National Library of Medicine) search by using the search headings neoplasia, preneoplasia, dysplasia, adenoma, serrated polyps, and Barrett's esophagus between the years 1980 and 2009.

CONCLUSIONS

Many types of lesions throughout the tubal gut fulfill the most basic and classic principles of a neoplastic precursor lesion but lack conventional morphologic evidence of dysplasia and/or maintain the capacity for cell differentiation and maturation. All of these lesions, such as squamous dysplasia of the esophagus, dysplasia in Barrett esophagus, and hyperplastic/serrated polyps of the colon, represent early neoplastic precursor lesions but without conventional histologic features of dysplasia. It is important for pathologists to be aware of these lesions, both for diagnostic and prognostic purposes, but also so that future studies can be performed with regard to risk stratification of patients.

Cost-effectiveness of treatment and endoscopic surveillance of precancerous lesions to prevent gastric cancer

BACKGROUND

Although surveillance for Barrett esophagus and other gastrointestinal precancerous conditions is recommended, no analogous guidelines exist for gastric lesions. The objective of this study was to estimate the clinical benefits and cost-effectiveness of treatment and endoscopic surveillance to prevent gastric cancer.

METHODS

The authors developed a state-transition decision model for a cohort of US men with a recent incidental diagnosis of gastric precancerous lesions (dysplasia, intestinal metaplasia, or atrophy). Strategies included 1) no surveillance or treatment and 2) referral for surveillance and treatment, and varied by surveillance frequency (none, every 10 years, every 5 years, or every year) and treatment modality for dysplastic and cancerous lesions (surgery or endoscopic mucosal resection [EMR]). The term "post-treatment surveillance" was restricted to surveillance of individuals after treatment. Data were based on published literature and databases. Outcomes included lifetime gastric cancer risk, quality-adjusted life expectancy, lifetime costs, and incremental cost-effectiveness ratios.

RESULTS

For a cohort of men with dysplasia aged 50 years, the lifetime gastric cancer risk was 5.9%. EMR with annual surveillance reduced the lifetime cancer risk by 90% and cost $39,800 per quality-adjusted life year (QALY). Addition of post-treatment surveillance every 10 years provided little incremental benefit ( approximately 5%) but cost >$1 million per QALY. Results were most sensitive to surgical risks and the proportion of lesions completely removed with EMR. For intestinal metaplasia, surveillance every 10 years reduced lifetime cancer risk by 61% and cost $544,500 per QALY.

CONCLUSIONS

EMR with surveillance every 1 to 5 years for gastric dysplasia was promising for secondary cancer prevention and had a cost-effectiveness ratio that would be considered attractive in the United States. Endoscopic surveillance of less advanced lesions did not appear to be cost-effective, except possibly for immigrants from high-risk countries.

Grading of gastric foveolar-type dysplasia in Barrett's esophagus

Dysplasia is the gold standard biomarker of cancer risk in Barrett's esophagus, but its diagnosis remains difficult. This is due in part to its multitude of histological appearances. One aspect receiving little attention concerns gastric-type Barrett's dysplasia, which is distinctly different from the well-established intestinal variant. Recognition of gastric-type dysplasia and development of separate grading criteria are required. The prevalence, diagnostic criteria, and natural history of gastric-type Barrett's dysplasia were systematically evaluated in 1854 endoscopic biopsies from a cohort of 200 consecutive Barrett's dysplasia patients. Goblet cells were present in all cases, confirming the utility of this defining feature of Barrett's esophagus. The prevalence of Barrett's gastric-type dysplasia was 15% at the patient level (30 of 200 patients) and 20% at the biopsy level (166 of 852 dysplastic biopsies). Gastric-type dysplasia uniformly showed non-stratified, basally oriented nuclei as the major criterion for distinguishing it from intestinal-type Barrett's dysplasia. As such, loss of nuclear polarity, as the most objective criterion to distinguish intestinal-type low- and high-grade dysplasia, cannot be applied to gastric-type dysplasia. Rather, discriminatory features included increased nuclear size with a high-grade dysplasia cutoff by receiver operating characteristic (ROC) analysis approximating 3-4 times the size of a mature lymphocyte, providing an optimal sensitivity, specificity, and area under the curve of 0.78, 0.90, and 0.90 (95% CI: (0.87, 0.93)), respectively. Crowded, irregular glandular architecture (P<0.001) was more common in high-grade lesions (P<0.001), as was eosinophilic and oncocytic cytoplasm relative to the mucinous cytoplasm (P<0.001), prominent nucleoli (P<0.001), mild nuclear pleomorphism (P<0.001), and villiform architecture (P<0.001). During follow-up, 64% (7 of 11) of patients with pure gastric and 26% (5 of 19) with mixed gastric and intestinal dysplasia underwent neoplastic progression. The recognition of Barrett's gastric-type dysplasia and use of the proposed grading criteria should promote better diagnostic classification of the Barrett's neoplastic spectrum.

Cell polarity protein Lgl2 is lost or aberrantly localized in gastric dysplasia and adenocarcinoma: an immunohistochemical study

The diagnosis of gastric epithelial dysplasia, a precursor lesion of gastric adenocarcinoma, is hindered by interobserver variability and by its resemblance to regenerative changes. Loss of cell polarity, a histological feature of gastric epithelial dysplasia, may be difficult to ascertain, especially in the setting of inflammation or injury. A biomarker of cell polarity could be useful in diagnosis of dysplasia, but has not been reported. The Lethal giant larvae (lgl) gene controls apical-basal polarity of epithelial cells in Drosophila, and has properties of a tumor-suppressor gene. Two homologs, lgl1 and lgl2, are present in mammals and lgl2 mRNA is highly expressed in the stomach. The goal of our study was to test the hypothesis that Lgl2 protein expression and/or localization are disrupted in gastric epithelial dysplasia and adenocarcinoma. Routinely processed pathology specimens including 94 benign mucosae of digestive organs, in addition to 36 reactive gastropathy, 57 gastric epithelial dysplasia, and 77 gastric adenocarcinomas, were immunostained for Lgl2 protein. All normal, reactive, and chronically inflamed gastric epithelia showed basolateral Lgl2 staining. Normal esophageal, duodenal, colonic, biliary, and pancreatic duct mucosae, as well as gastric intestinal metaplasia, did not express Lgl2. All but one case each of gastric epithelial dysplasia and adenocarcinoma showed either complete loss of anti-Lgl2 immunoreactivity or diffuse, mostly weak, cytoplasmic staining. Complete loss of immunoreactivity was significantly more often observed in diffuse-type than in intestinal-type adenocarcinomas (79 vs 48%, respectively). Our data suggest that Lgl2 expression is either aberrantly localized or lost in gastric epithelial dysplasia and adenocarcinoma, whereas it is maintained in reactive gastric mucosa. We propose that Lgl2 may be a potential marker to rule out gastric epithelial dysplasia and adenocarcinoma in diagnostic specimens. However, the consistently negative anti-Lgl2 immunoreactivity seen in intestinal metaplasia does not allow differentiation of dysplasia from intestinal metaplasia with reactive change.

Management of gastric polyps: a pathology-based guide for gastroenterologists

1-4% of patients who undergo gastric biopsy have gastric polyps. These lesions may be true epithelial polyps, heterotopias, lymphoid tissue, or stromal lesions. Hyperplastic polyps, which arise in patients with underlying gastritis, and fundic-gland polyps, which are associated with PPI therapy, are the most common gastric polyps; however, prevalence varies widely relative to the local prevalence of Helicobacter pylori infection and use of PPI therapy. Some polyps have characteristic topography, size, and endoscopic appearance. Approximately 20% of biopsy specimens identified endoscopically as polyps have no definite pathological diagnosis. Evaluation of the phenotype of the gastric mucosa that surrounds a lesion will provide significant information crucial to the evaluation, diagnosis and management of a patient. The presence of a gastric adenoma should prompt the search for a coexistent carcinoma. The endoscopic characteristics, histopathology, pathogenesis, and management recommendations of polyps and common polypoid lesions in the stomach are discussed in this Review.

The current spectrum of gastric polyps: a 1-year national study of over 120,000 patients

OBJECTIVES

To use a large pathology database (Caris Diagnostics) to analyze the frequency and associations of gastric polyps in a nationwide US population.

METHODS

A total of 121,564 esophagogastroduodenoscopy (EGD) procedures from private practices in 36 states in the Caris Diagnostics database from 1 April 2007 to 31 March 2008 were searched for the endoscopic designations of polyp, nodule, and mass, and for the pathological diagnoses that commonly present as gastric polyps. Pertinent demographic data, clinical indications for EGD, and information regarding Helicobacter pylori infection, reactive gastropathy, chronic inactive gastritis, and intestinal metaplasia were also obtained.

RESULTS

A total of 78,909 of the 121,564 patients who underwent EGD had gastric biopsies. The prevalence of gastric polyps in the EGD population was 6.35%; 77% were fundic gland polyps, 17% hyperplastic polyps/polypoid foveolar hyperplasia, 0.69% adenomas, and 0.1% inflammatory fibroid polyps. Malignant neoplasms were slightly >2%. None of the benign gastric polyps had a significant positive association with concurrent H. pylori infection; intestinal metaplasia was detected in the background of 52.2% of carcinoids, 29.6% of adenomas, 20.1% of xanthomas, and 13% of adenocarcinomas and hyperplastic polyps. Adenomas were rarely associated with synchronous adenocarcinomas.

CONCLUSIONS

The relative prevalence of fundic gland polyps in this population was much higher than that reported earlier, most likely because of the widespread use of proton pump inhibitors. H. pylori- and atrophy-associated polyps, including adenomas, were less common than in earlier series.

CpG island methylation in premalignant stages of gastric carcinoma

There are limited reports on methylation analysis of the premalignant lesions of gastric carcinoma thus far. This is despite the fact that gastric carcinoma is one of the tumors with a high frequency of CpG island hypermethylation. To determine the frequency and timing of hypermethylation during multistep gastric carcinogenesis, non-neoplastic gastric mucosa (n = 118), adenomas (n = 61), and carcinomas (n = 64) were analyzed for their p16, human Mut L homologue 1 (hMLH1), death-associated protein (DAP)-kinase, thromobospondin-1 (THBS1), and tissue inhibitor of metalloproteinase 3 (TIMP-3) methylation status using methylation-specific PCR. Three different classes of methylation behaviors were found in the five tested genes. DAP-kinase was methylated at a similar frequency in all four stages, whereas hMLH1 and p16 were methylated in cancer samples (20.3% and 42.2%, respectively) more frequently than in intestinal metaplasia (6.3% and 2.1%, respectively) or adenomas (9.8% and 11.5%, respectively). However, hMLH1 and p16 were not methylated in chronic gastritis. THBS-1 and TIMP-3 were methylated in all stages but showed a marked increase in hypermethylation frequency from chronic gastritis (10.1% and 14.5%, respectively) to intestinal metaplasia (34.7% and 36.7%, respectively; P < 0.05) and from adenomas (28.3% and 26.7%, respectively) to carcinomas (48.4% and 57.4%, respectively: P < 0.05). The hMLH1, THBS1, and TIMP-3 hypermethylation frequencies were similar in both intestinal metaplasia and adenomas, but the p16 hypermethylation frequency tended to be higher in adenomas (11.5%) than in intestinal metaplasia (2.1%; P = 0.073). The average number of methylated genes was 0.6, 1.1, 1.1, and 2.0 per five genes per sample in chronic gastritis, intestinal metaplasia, adenomas, and carcinomas, respectively. This shows a marked increase in methylated genes from non-metaplastic mucosa to intestinal metaplasia (P = 0.001) as well as from premalignant lesions to carcinomas (P = 0.002). These results suggest that CpG island hypermethylation occur early in multistep gastric carcinogenesis and tend to accumulate along the multistep carcinogenesis.