Genetic abnormalities during transition from Helicobacter-pylori-associated gastritis to low-grade MALToma

Risk of second malignancies in patients with gastric marginal zone lymphomas of mucosa associate lymphoid tissue (MALT)

BACKGROUND

It is controversial whether patients with gastric marginal zone lymphomas of mucosa associated lymphoid tissue (MALT) have higher risk of second malignancies. The aim of this study was to define the risk of second malignancies in these patients.

METHODS

We analyzed prospective follow-up data of 146 consecutive patients with gastric MALT lymphoma treated at Aichi Cancer Center Hospital and compared the incidence of second malignancies with that in the general population. We calculated the standardized incidence ratio (SIR), using age- and sex-specific incidence rates from the Aichi Cancer Registry.

RESULTS

The median follow-up period was 74 months. A total of 27 tumors occurred in 22 patients (15.1%), including 19 solid tumors. Of these, nine tumors were detected concomitantly with, and 18 tumors following, the diagnosis of gastric MALT lymphoma. Four patients had two second malignancies each. For the entire group, the SIR of an additional malignancy was 3.39 (95% confidence interval [CI] 2.11-4.66). An increased incidence of solid tumors (SIR 2.91 [1.60-4.22]) and hematologic malignancies (SIR 5.54 [1.70-9.38]) were seen. In addition, there was increased risk for development of second malignancies during follow up (SIR 2.26 [1.21-3.30]). Chemotherapy for treatment of MALT was an independent risk factor for second malignancies (age-sex adjusted hazard ratio 3.98 [1.47-10.79].

CONCLUSIONS

Compared with the general population, patients with gastric MALT lymphoma are at increased risk for second malignancies, including gastric cancer.

Non-Hodgkin lymphoma risk and variants in genes controlling lymphocyte development

Non-Hodgkin lymphomas (NHL) are a heterogeneous group of solid tumours of lymphoid cell origin. Three important aspects of lymphocyte development include immunity and inflammation, DNA repair, and programmed cell death. We have used a previously established case-control study of NHL to ask whether genetic variation in genes involved in these three important processes influences risk of this cancer. 118 genes in these three categories were tagged with single nucleotide polymorphisms (SNPs), which were tested for association with NHL and its subtypes. The main analysis used logistic regression (additive model) to estimate odds ratios in European-ancestry cases and controls. 599 SNPs and 1116 samples (569 cases and 547 controls) passed quality control measures and were included in analyses. Following multiple-testing correction, one SNP in MSH3, a mismatch repair gene, showed an association with diffuse large B-cell lymphoma (OR: 1.91; 95% CI: 1.41–2.59; uncorrected p = 0.00003; corrected p = 0.010). This association was not replicated in an independent European-ancestry sample set of 251 diffuse large B-cell lymphoma cases and 737 controls, indicating this result was likely a false positive. It is likely that moderate sample size, inter-subtype and other genetic heterogeneity, and small true effect sizes account for the lack of replicable findings.

Early-stage gastric MALT lymphoma: is it a truly localized disease?

Early-stage gastric mucosa-associated lymphoid tissue lymphoma (GML) is considered a localized disease with an indolent course. Circulating malignant cells have been detected in other early-stage indolent lymphomas by molecular methods. We investigated the incidence of occult blood disease in early-stage GML patients, its impact on clinical outcome, and the similarity between blood and gastric lymphocytic clones. Sixty-two patients with localized GML were included in the study; 51 of them had Helicobacter pylori infection. Monoclonality was investigated by leader polymerase chain reaction. Sequencing was performed for the immunoglobulin variable gene (VH) analysis. Blood involvement was absent in all patients by conventional staging methods. In the whole group of 62 patients, the incidence of blood IgH rearrangement was 45%, and this did not correlate with baseline patient characteristics. The monoclonal blood and gastric products of five patients were sequenced and compared with each other. Clonal identity was evident in four of five patients. The VH3 gene was the most frequently used, both in the blood and in the stomach. Early-stage GML is not a truly localized disease because half the patients had a circulating clone, probably identical to the gastric one. The clinical significance of occult blood disease and the potential appropriate intervention need to be further investigated.

Risk of Second Cancer in Nongastric Marginal Zone B-Cell Lymphomas of Mucosa-Associated Lymphoid Tissue: A Population-Based Study from Northern Italy

PURPOSE

The aim of this study was to define the risk of second cancer in nongastric marginal zone lymphomas of mucosa-associated lymphoid tissue (MALT).

EXPERIMENTAL DESIGN

We considered for the analysis 157 patients with a confirmed histology of marginal zone B-cell lymphoma of MALT, presenting with a clinically prevalent extranodal site of disease, except for stomach. All patients came from two hematologic institutions of Northern Italy. We compared the occurrence of second cancer with respect to the general population by calculating the standardized incidence ratio, with the age- and sex-specific incidence rates of a cancer registry of Northern Italy (Lombardia) as a reference.

RESULTS

A history of solid neoplasia was present in 29 (18%) patients for a total number of 30 neoplasms: 25 solid tumors, 2 hematologic diseases (1 Hodgkin's lymphoma and 1 essential thrombocythemia), and 3 nonmelanoma in situ skin cancers. In 4 patients, the site of cancer and lymphoma was the same. In 21 cases the solid tumor preceded the MALToma, in 3 the neoplasm was concomitant, whereas in 6 it was subsequent. For the entire group, the standardized incidence ratio of an additional malignancy was 0.8 [95% confidence interval (95% CI), 0.55-1.17; P = 0.2]. After excluding nonmelanoma skin cancer, the standardized incidence ratio of a second tumor was 0.75 (95% CI, 0.5-1.12; P = 0.2). After excluding all previous malignancies, the standardized incidence ratio of a second cancer was 1.32 (95% CI, 0.69-2.55; P = 0.4). The comparison of risks between males and females was not significant in each group analysis.

CONCLUSIONS

Patients with nongastric MALT lymphomas are not at increased risk for other neoplasms compared with the general population of the same geographic area.

Microsatellite instability in patients with chronic B-cell lymphocytic leukaemia

The purpose of our study was to evaluate the microsatellite instability (MSI) at selected loci with known involvement in the oncogenesis of chronic B-cell lymphocytic leukaemia (B-CLL). DNA from B cells (tumour cells) and from T cells (normal controls) of 27 samples of 26 patients with previously untreated B-CLL was extracted. Microsatellite instability in six microsatellite markers was tested using GeneScan Analysis Software. The rate of replication errors positive phenotype (RER+) was determined (MSI in more than 30% of examined loci). RER+ was found in four out of 27 paients (14.8%). A larger proportion of patients with stage C B-CLL exhibited RER+ than those with stage A or B (P<0.05). A higher prevalence of RER+ was demonstrated in a subgroup of patients with additional malignancies (three out of eight patients) in comparison with patients with B-CLL alone (1/19) (P=0.031). In conclusion, our study demonstrated that MSI might have a more prominent role in pathogenesis of B-CLL than reported todate. This may result from a selection of microsatellite markers adjacent to chromosomal loci, which are involved in B-cell malignancies, and using GeneScan Analysis Software, which is most modern and precise method of microsatellite analysis.

Microsatellite instability in gastric MALT lymphoma

The role of microsatellite instability and defects in DNA mismatch repair mechanism in the pathogenesis of gastric lymphoma of mucosa-associated lymphoid tissue (MALT) type is still controversial, as both negative and positive findings have been reported. This may be explained mainly by arbitrary selection of the tested loci, the use of various techniques of microsatellite instability analysis and by different definitions of replication error positive phenotype. The aim of our study was to evaluate the instability at selected microsatellite markers using the GeneScan Analysis Software. DNA from paraffin-embedded tissue blocks of 13 previously untreated patients with localized gastric MALT lymphoma was extracted. Five microsatellite markers, which are located in hMSH2, hMLH1, P16, APC and MLL loci, were selected from the genetic database. We found genetic instability in tumors of 9/13 patients with gastric MALT lymphoma (69%). Seven of them had replication-error-positive phenotype (54%). Microsatellite instability was found in 39% of the samples in the MLL locus, 39% in the APC, 46% in the P16, 23% in the hMLH1 and none in the hMSH2. This study demonstrates that microsatellite instability has more prominent role in pathogenesis of gastric MALT lymphoma than reported to date. We suggest that microsatellite instability should be analyzed with markers adjacent to chromosomal loci that are involved in lymphomas. Our findings support the 'Real Common Target genes' theory of high rate of microsatellite instability in specific genes, which are associated with related tumors.

Marginal Zone B-cell Lymphoma (MALT Lymphoma)

The preferred terminology for mucosa-associated lymphoid tissue (MALT) lymphoma of the stomach (variously referred to as MALT lymphoma, MALToma, low-grade MALToma, or pseudolymphoma) is marginal zone B-cell lymphoma (MZBL). MZBL, the hallmark of which is the lymphoepithelial lesion, develops as a consequence of Helicobacter pylori infection in susceptible individuals. In general, MZBL is slow growing, can remain localized for years, and has an excellent prognosis. Staging involves endoscopy with biopsy, computed tomography scanning, and endoscopic ultrasound. In patients with limited disease, eradication of H. pylori leads to remission. In patients who fail eradication therapy or have more extensive disease, surgery, chemotherapy, and radiation alone and in various combinations have been used successfully.

p53 expression, K-ras gene mutation and microsatellite instability in gastric B-cell lymphomas

BACKGROUND AND AIMS

Genetic mechanisms involved in the development of gastric B-cell lymphomas remain unclear. The aim of the present study was to clarify the roles of mutations of the p53 and K-ras genes, and microsatellite instability (MSI) in the development of gastric B-cell lymphomas.

METHODS

We investigated p53 immunoreactivity, mutations of the K-ras gene, and MSI in 27 gastric marginal zone B-cell lymphomas of mucosa-associated lymphoid tissue type (MZBCL) and 24 diffuse large B-cell lymphomas (DLBCL). p53 immunoreactivity was examined using a monoclonal antibody, DO-7. Mutation of the K-ras gene was detected by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis. MSI was examined at five microsatellite loci with a microsatellite assay. Cases were classified as having high-frequency MSI (MSI-H) (>/= 2 loci showing instability), low-frequency MSI (MSI-L) (only one locus showing instability), or as microsatellite stable.

RESULTS

p53 immunoreactivity was detected in 1 of 16 (6%) MZBCL and 8 of 19 (42%) DLBCL. Frequency of p53 immunoreactivity in DLBCL was significantly higher than that in MZBCL (P = 0.018). MSI-H was detected only in 1 of 20 (5%) DLBCL. None of the cases examined showed mutation of the K-ras gene.

CONCLUSIONS

These data suggest that mutations of the p53 gene may play an important role in the development of gastric DLBCL, and that mutations of the K-ras gene and MSI may be involved in little part of the development of gastric B-cell lymphomas.

Gastric marginal zone lymphoma is associated with polymorphisms in genes involved in inflammatory response and antioxidative capacity

Gastric marginal zone lymphoma (GMZL) is strongly associated with Helicobacter pylori infection, which induces a chronic inflammatory response. Inflammation can result in DNA damage related to its severity, the cellular antioxidant capacity, and the integrity of DNA repair mechanisms. Interleukin-1 (IL-1) polymorphisms have been shown to be important mediators of inflammation, while glutathione S-transferase GST T1 and GST M1 polymorphisms are believed to affect cellular antioxidant capacity. We aimed to determine whether polymorphisms at the IL-1 and GST T1 and GST M1 loci modulate the risk of developing GMZL. Blood and biopsy samples were obtained for a historical series of 66 GMZL cases, whereas blood samples were available from 163 healthy controls. Genotypes were obtained for GST T1, GST M1, IL-1 RN, and IL-1B-31 using PCR-based techniques. H pylori infection was found in 86.0% of cases, whereas in the control population only 37.4% tested positive. The IL-1 RN 2/2 genotype was significantly associated with risk of GMZL (odds ratio [OR], 5.51; 95% confidence interval [CI] 2.16-14.07), but not the IL-1B-31 genotype. Likewise, the GST T1 null genotype was strongly associated with risk of GMZL (OR, 9.51; 95% CI 4.57-19.81), but not the GST M1 genotype. Evidence was found of effect modification between the IL-1 RN and GST T1 genotypes (P =.02). The combination of the IL-1 RN 2/2 and GST T1 null genotype was most strongly associated with risk of GMZL (OR, 32.29; 95% CI 6.92-150-63). These results support the hypothesis that the risk of developing GMZL is influenced by inter-individual variation in the cellular inflammatory immune responses to H pylori infection, and to antioxidative capacity.

Gastric marginal zone B-cell lymphomas of MALT type develop along 2 distinct pathogenetic pathways

Low-grade marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) type can transform into high-grade diffuse large B-cell lymphoma (DLBCL). Up to 60% of the MALT lymphomas contain the recently described t(11;18). However, this translocation has not been detected in any DLBCL so far. To elucidate the pathogenesis of these tumors, microsatellite screening of 24 gastric MALT lymphomas was performed and the results were compared with aberrations detected in a previous study on gastric DLBCL. The most frequent aberration, found in 21% of the MALT lymphomas that were exclusively t(11;18)-negative cases, was amplification of the 3q26.2-27 region (harboring the locus of the BCL6 gene). Allelic imbalances in regions 3q26.2-27, 6q23.3-25, 7q31, 11q23-24, and 18q21 were shared by both MALT lymphoma and DLBCL. Loss of heterozygosity in regions 5q21 (APC gene locus), 9p21 (INK4A/ARF), 13q14 (RB), and 17p13 (p53) and allelic imbalances in 2p16, 6p23, and 12p12-13 occurred exclusively in DLBCL. Only one of 10 t(11;18)-positive MALT lymphomas showed an additional clonal abnormality. These tumors thus display features of a clonal proliferation characterized by the presence of the t(11;18). However, they only rarely display secondary aberrations and do not seem to transform into DLBCL. In contrast, t(11;18)-negative MALT lymphomas show numerous allelic imbalances--some of them identical with aberrations seen in DLBCL--suggesting that this group is the source of tumors eventually transforming into high-grade DLBCL.

Histological and immunological parameters to predict treatment outcome of Helicobacter pylori eradication in low-grade gastric MALT lymphoma

Helicobacter pylori eradication is generally accepted as the first choice of treatment for stage IE low-grade gastric MALT lymphoma (mucosa-associated lymphoid tissue-type lymphoma). Treatment failure may be attributed to the extent of the disease and to progression into an antigen-independent phase. This study assessed the value of morphological grading and the expression of the co-stimulatory markers CD40, CD80 and CD86 and their ligands to predict clinical outcome in 23 consecutive low-grade MALT lymphoma patients treated with H. pylori eradication. Complete regression was achieved in 13/23 patients (56%), partial regression in two (9%), and no response in eight (35%). Histological grading was highly predictive of clinical response, especially in stage IE(1) patients, with complete remissions in 10/12 tumours with purely low-grade (type A) morphology and 1/8 tumours with increased numbers of blasts (type B) (p=0.0046) and was related to the expression of costimulatory markers (p=0.0061). Moreover, CD86 as a single marker proved to be of predictive value for treatment outcome (p=0.0086). These results suggest that morphological grading and immunological criteria can be defined to recognize the transition into the antigen-independent phase of gastric MALT-NHL. In addition to clinical stage, these critera may in future serve as a practical pathological guide to the choice of therapy.

Genetic instability is associated with histological transformation of follicle center lymphoma

Follicle center lymphoma (FCL) is an indolent B cell non-Hodgkin's lymphoma (NHL) characterized genetically by the t(14;18) translocation. Histological transformation and clinical progression of FCLs are frequently associated with secondary genetic alterations at both nucleic acid and chromosomal levels. To determine the type and pattern of genomic instability occurring in histological transformation of FCLs and the role of DNA mismatch repair defects in this procedure, we have performed microsatellite analysis, comparative genomic hybridization (CGH) and mutational analysis of hMLH1 and hMSH2 genes on serial biopsy specimens from patients with FCL transformed to diffuse large cell lymphoma (DLCL). Paired biopsy samples of eight patients were analyzed for microsatellite instability and structural alterations for hMLH1 and hMSH2 genes, and tumor samples of five patients were subjected to CGH analysis. A high level of microsatellite instability was associated with histological transformation of two cases of FCL, but no mutations of the hMLH1 and hMSH2 genes were detected in any of the lymphoma samples. In the five cases subjected to CGH analysis, the histological transformation of FCLs was associated with genomic imbalances at 21 chromosomal regions. The genomic abnormalities found were rather heterogeneous and none of the genetic changes were overrepresented in the transformed DLCLs. These data suggest that histological transformation of FCLs to DLCL is frequently associated with genome wide instability at both nucleic acid and chromosomal levels, although mutations of the hMSH1 and hMLH2 genes are not involved in this process.

Low-grade MALT lymphoma of the stomach: a review of treatment options

PURPOSE

Low-grade mucosa-associated lymphoid tissue (MALT) lymphoma of the stomach (MLS) is often associated with the presence of Helicobacter pylori (H. pylori) bacteria. Eradication of the infection with antibiotic therapy may result in regression of the lymphoma. But when antibiotic treatment fails to reverse the malignant process or if H. pylori is absent, other treatment options should be considered. Because MLS is often confined to the stomach and regional lymph nodes, it is potentially curable with local therapy. Endoscopy and improved imaging, with endoscopic ultrasound (EUS) and computerized tomography (CT), have reduced the prior dependence on surgery for diagnosis and staging of gastric lymphomas.

METHODS AND RESULTS

This review details the advances in the diagnosis, classification, and imaging of MLS. We also describe the experience that supports the use of radiation therapy as the preferred treatment of MLS in patients who have not responded to antibiotic therapy or have not had evidence for H. pylori infection.

CONCLUSIONS

Radiation therapy for MLS is not only effective and safe, but offers the significant advantage of low morbidity and gastric function preservation.

Helicobacter pylori. One bacterium and a broad spectrum of human disease! An overview

Since the historical rediscovery of gastric spiral Helicobacter pylori in the gastric mucosa of patients with chronic gastritis by Warren and Marshall in 1983, peptic ulcer disease has been largely viewed as being of infectious aetiology. Indeed, there is a strong association between the presence of H. pylori and chronic active gastritis in histology. The bacterium can be isolated in not less than 70% of gastric and in over 90% of duodenal ulcer patients. Eradication of the organism has been associated with histologic improvement of gastritis, lower relapse rate and less risk of bleeding from duodenal ulcer. The bacterium possesses several virulence factors enabling it to survive the strong acid milieu inside the stomach and possibly damaging host tissues. The sequence of events by which the bacterium might cause gastric or duodenal ulcer is still not fully elucidated and Koch's postulates have never been fulfilled. In the majority of individuals, H. pylori infection is largely or entirely asymptomatic and there is no convincing data to suggest an increase in the prevalence of peptic ulcer disease among these subjects. An increasingly growing body of literature suggests an association between colonization by H. pylori in the stomach and a risk for developing gastric mucosa-associated lymphoid tissue (MALT), MALT lymphoma, gastric adenocarcinoma and even pancreatic adenocarcinoma. The bacterium has been implicated also in a number of extra-gastrointestinal disorders such as ischaemic heart disease, ischaemic cerebrovascular disease, atherosclerosis, and skin diseases such as rosacea, but a causal role for the bacterium is missing. Eradication of H. pylori thus seems to be a beneficial impact on human health. Various drug regimens are in use to eradicate H. pylori involving the administration of three or four drugs including bismuth compounds, metronidazole, clarithromycin, tetracyclines, amoxycillin, ranitidine, omeprazole for 1-2 weeks. The financial burden, side effects and emergence of drug resistant strains due to an increase in the use in antibiotics for H. pylori eradication therapy need further reconsideration.

Primary macroglobulinemia with t(11;18)(q21;q21)

These are the first cases of primary macroglobulinemia (PMG) with t(11;18)(q21;q21) reported in the literature. The first case was a 77-year-old man with macroglobulinemia (serum IgM: 8.36 g/dL). Abnormal lymphoid cells were detected in the blood and bone marrow. Immunologic and karyotypic analyses revealed that abnormal cells were positive for surface IgM-k, CD19, and CD20, negative for CD5 and CD10, and all had a t(11;18)(q21;q21). The second case was a 57-year-old woman with macroglobulinemia (serum IgM: 12.0 g/dL). Abnormal lymphoid cells were detected in blood and marrow, and cells were positive for surface IgM-lambda, CD19, and CD20, and negative for CD5 and CD10. Plasma cells bearing cytoplasmic IgM-lambda were increased in pleural fluid. Karyotyping demonstrated t(2;11;18)(q21-23;q21;q21). Rearrangements within BCL2 and YES genes located at 18q21 were not detected. Sixteen other cases with t(11;18)(q21;q21) have been reported in marginal zone B-cell lymphoma. Therefore, our report is in agreement with the finding that part of primary macroglobulinemia is a variant of marginal zone B-cell lymphoma.

Infection, immunity, and cancer

A significant percentage of human cancers worldwide are associated with infections due to known viruses, including human papillomaviruses (cervical cancer and other skin cancers), human T-lymphotropic viruses (adult T-cell leukemias and lymphomas in endemic areas), hepatitis B virus (liver cancer), and Epstein-Barr virus (Burkitt lymphoma and nasopharyngeal carcinoma). The fraction of human cancers attributable to infection may now need to be revised in light of the fact that new viral associations have been discovered and other nonviral associations have been identified. This article addresses the increasingly recognized role of infectious agents as precipitants of human neoplasia and the possibility that novel diagnostic, therapeutic, and chemopreventive strategies may emanate directly from research directed at identifying and understanding these agents.

CDR3 sequences of MALT lymphoma show homology with those of autoreactive B-cell lines

We have examined the CDR3 sequence and adjacent regions of immunoglobulin genes from B-cell lymphoma of mucosa-associated lymphoid tissue (MALT). Twenty-nine sequences (15 sequences from 13 low-grade MALT lymphomas, marginal zone B-cell lymphomas; 7 sequences from 6 high-grade MALT lymphomas; 7 sequences from 7 diffuse large cell lymphomas) were obtained after cloning of the polymerase chain reaction-amplified segments. In the low-grade MALT, high-grade MALT and diffuse large cell lymphomas, the mean length of the CDR3 region was 47.6+/-10.31 (range 21 to 60), 38.71+/-10.37 (range 27 to 57) and 40.86+/-3.34 (range 39 to 48) nucleotides, respectively. The length of the CDR3 region was significantly greater in the low-grade MALT lymphoma group than in the other two groups. CDR3 sequences in lymphoma cell clones of 14 cases showed 60 to 81% homology with autoantibody-associated lymphocyte clones including rheumatoid factor. The incidences of these autoantibody-associated lymphocyte clones were higher in the high-grade MALT (4/6) and diffuse large lymphomas (5/7) than in the low-grade MALT lymphoma (5/13). Cases with more than 70% homology at the nucleotide level were found to have 71 to 82% homology with autoantibodies at the protein level in the low-grade MALT lymphomas (2/13), and 67% homology in the high-grade MALT lymphomas (2/7). These results indicate that MALT lymphomas may be derived from the malignant transformation of autoreactive B-cells.

Serum antibody responses to Helicobacter pylori and the cagA marker in patients with mucosa-associated lymphoid tissue lymphoma

The lymphoma of the mucosa-associated lymphoid tissue (MALT) of the stomach has been linked to Helicobacter pylori infection, but the mechanisms involved in B-cell proliferation remain elusive. In a search for putative H. pylori-specific monoclonal immunoglobulin production, an H. pylori strain was isolated from 10 patients with MALT lymphoma and used to detect the specific serum antibody response to the homologous strain by immunoblotting. Moreover, the antigenicity of the different strains was compared by using each of the 10 sera. We found that the different strains induced highly variable patterns of systemic immunoglobulin G antibody response, although several bacterial antigens, such as the 60-kDa urease B, were often recognized by the different sera. The cagA marker was detected in the strains by PCR with specific primers and by dot blot analysis, and the CagA protein was found in the sera of 4 of the 10 patients by immunoblotting. In conclusion, MALT lymphoma patients, like other patients with H. pylori gastritis, exhibit a polymorphic systemic antibody response, despite an apparently similar antigenic profile. The CagA marker of pathogenicity is not associated with this disease.

Microsatellite instability in gastric MALT lymphomas and other associated neoplasms

BACKGROUND

Microsatellite instability (MSI), caused by a reduced efficacy of the DNA mismatch repair (MMR) machinery, represents a type of genomic instability frequently detected in HNPCC spectrum cancers and in a subset of sporadic carcinomas. The involvement of MSI in the pathogenesis of gastric lymphoma of mucosa-associated lymphoid tissue (MALT) has never been conclusively investigated. In this study, we tested the presence of MSI in tumor samples of patients harboring both MALT lymphomas and other types of malignancies.

MATERIALS AND METHODS

We examined 10 microsatellite loci (D3S11, D3S1261, D3S1265, D6S262, D6S193, BAT-26, BAT-25, D17S250, APC, D2S123) out of a total of 34 primary tumors from 14 patients with MALT lymphomas and one or more additional neoplasms. The patients' MSI results were also tested for an association with a positive family history of cancer.

RESULTS

MSI, defined by the presence of microsatellite alterations in more than 40% of the examined loci, was scored negative in all tumors studied, and pedigree analysis failed to identify any condition of familial cancer among the patients examined.

CONCLUSIONS

The present study suggests that defects in DNA mismatch repair do not contribute significantly to the molecular pathogenesis of MALT lymphomas and associated neoplasms.

Helicobacter pylori non-cytotoxic genotype enhances mucosal gastrin and mast cell tryptase

AIMS

To determine the association, if any, between H pylori genotype and the gastric mucosal variations in the levels of gastrin, somatostatin, tryptase, and histamine.

METHODS

49 patients affected by duodenal ulcer and 48 by non-ulcer dyspepsia were studied. To identify the H pylori genotype, the presence of the cagA gene and vacA alleles m1, m2, s1, and s2 were analysed by polymerase chain reaction. Gastrin, somatostatin, tryptase, and histamine were measured in antral mucosal biopsies.

RESULTS

57 patients were infected with H pylori (30 with duodenal ulcer and 27 with non-ulcer dyspepsia). Gastrin and tryptase were increased in patients with H pylori infection, although the variations were statistically significant only for gastrin; somatostatin and histamine were not influenced by H pylori infection. In patients with non-ulcer dyspepsia the absence of the cagA gene and the presence of vacA alleles s2 and m2 were associated with higher values of tryptase and to a lesser extent of gastrin. These associations were not found in patients with duodenal ulcer.

CONCLUSIONS

The cagA negative s2m2 strain of H pylori may be less dangerous for the gastric mucosa than other H pylori strains since it enhances tryptase production by gastric mucosal mast cells; this enzyme is thought to stimulate tissue turnover and favour wound healing.

Mucosa-associated lymphoid tissue lymphoma of the stomach: long term outcome after local treatment

BACKGROUND

Although antibiotic therapy is emerging as effective initial treatment for patients with gastric lymphoma of mucosa-associated lymphoid tissue (MALT), there is a subset of patients for whom antibiotics are ineffective or inappropriate. Surgical resection can be curative, but total gastrectomy may be required for the eradication of all disease. To identify the optimal nonantibiotic therapy for early stage gastric MALT lymphoma, the authors retrospectively evaluated the Massachusetts General Hospital experience with gastric MALT lymphoma.

METHODS

Disease patterns and treatment outcomes were retrospectively analyzed in data from 21 consecutive patients with gastric MALT lymphoma who were treated between 1978 and 1995 at the Massachusetts General Hospital.

RESULTS

Sixteen patients were Stage IE, and 5 were in higher stages. Treatment consisted of resection with or without radiation or chemotherapy (14 patients), radiation alone (4 patients), or radiation plus chemotherapy (2 patients). Thirteen Stage IE patients received local therapy only. The 10-year actuarial relapse free survival rate for Stage IE patients was 93%, with 1 relapse among 15 treated patients. Because the patient who relapsed was treated successfully with chemotherapy, the 10-year cancer free survival was 100%. Overall survival for Stage IE patients was 93% at 5 years and 58% at 10 years, with no deaths from lymphoma.

CONCLUSIONS

These data indicate that a high probability of long term remission can be achieved with only local treatment of patients with Stage I gastric MALT lymphoma. Preliminary results suggest that radiation therapy is well tolerated and effective and may well be the optimal nonantibiotic treatment for patients with localized gastric MALT lymphoma.

No evidence of replication error phenotype in primary gastric lymphoma of mucosa-associated lymphoid tissue

Replication error (RER) phenotype, caused by deficiency of DNA mismatch repair genes and revealed by widespread microsatellite instability, has been detected in subsets of a wide variety of solid tumors, but rarely in lymphomas in general. So far, the involvement of RER phenotype in the pathogenesis of gastric lymphoma of mucosa-associated lymphoid tissue (MALT) type has not been conclusively established. We therefore examined 9 microsatellite loci on 5 chromosomes [D2S123, D3S11, D3S1261, D3S1262, D3S1265, D6S262, D18S559, a CTTT(T) repeat in intron 20 of RBI gene and a CA repeat in p53 locus] in 33 cases of primary gastric MALT lymphoma for evidence of microsatellite instability by polymerase chain reaction using primers end-labeled with [gamma-33P] ATP. Although novel-length allele was observed in 7 of 33 cases (21.2%), none of these 7 cases showed changes in more than one locus. RER phenotype was scored as positive in a case when more than 1 of the 9 examined microsatellite loci showed length alterations. Accordingly, none of the 33 cases had a RER phenotype. This result suggests that the pathogenesis of gastric MALT lymphoma does not involve RER phenotype. It is consistent with the general observations in lymphomas, but is highly in contrast to a previous report showing more than 50% of MALT lymphomas with the RER phenotype.

Gastric low-grade mucosa-associated lymphoid tissue lymphomas: their histogenesis and high-grade transformation

Gastric low-grade mucosa-associated lymphoid tissue (MALT) lymphoma is a unique disease. A vast majority of lymphoma cells are centrocyte-like cells or resemble monocytoid B cells, and occasionally show plasmacytic differentiation. Immunophenotypical and immunogenotypical examinations have indicated that they are in the differentiation stage of memory B cells, whose normal counterparts are marginal zone lymphocytes or monocytoid B cells in the lymphoid tissues. It arises from chronic gastritis closely associated with Helicobacter pylori (H. pylori) infection. Mucosa-associated lymphoid tissue lymphomas of other organs are also based on acquired MALT associated with chronic inflammation or autoimmune diseases. Interestingly, the majority of gastric low-grade MALT lymphomas regress by the eradication of H. pylori. The lymphoma cells, however, are not derived from B cells reacting with H. pylori itself but from autoreactive B cells. Although the mechanism of their oncogenesis has not been clarified, previous data suggest that autoreactive B cells proliferate in response to H. pylori-specific T cells, presumably with some cytokines. The genetic instability of such B cells then induces chromosomal abnormalities including trisomy 3 and/or other genetic changes. These B cells have the ability of autonomic proliferation and, even so, they might be sensitive to T cell stimuli. Low-grade gastric lymphomas occasionally progress to high-grade malignancy. The high-grade component of MALT lymphomas are composed of large-sized lymphoma cells that are morphologically indistinguishable from nodal large B cell lymphomas. This high-grade transformation is associated with p53 abnormalities or Bcl-6 overexpression. Gastric MALT lymphoma may provide a useful model in understanding multistep lymphomagenesis.

Classification of primary gastric lymphomas according to histologic features

Histologic features of low-grade gastric lymphomas of mucosa-associated lymphoid tissue (MALT) have been extensively described, and transformation to a large cell (high-grade) lymphoma can occur. We characterize high-grade gastric lymphoma histologically in an attempt to distinguish between MALT-type and non-MALT-type lesions. We studied a series of 60 gastric lymphomas and characterized them clinically, histopathologically, and immunophenotypically. Low-grade gastric lymphomas were classified according to established criteria. High-grade lymphomas were classified in three groups based on the presence or absence of a low-grade component and lymphoepithelial lesions (LELs): 1) high-grade MALT lymphomas appearing in low-grade MALT lymphomas (LG/HG MALT lymphoma); 2) large cell lymphoma with LELs composed of large cells (high-grade LELs) but without a low-grade component (HG MALT lymphoma); and 3) diffuse large cell lymphoma without a low-grade MALT lymphoma component or LELs (DLCL). Twenty-two lymphomas were classified as low-grade MALT lymphomas, 16 as LG/HG MALT lymphomas, 10 as HG MALT lymphomas, and 12 as DLCL. B-cell immunophenotype was confirmed in all 55 cases in which immunophenotyping was performed. Low-grade LELs were seen in all low-grade MALT lymphomas, and CD20(L26) expression confirmed B-cell phenotype in the LELs in 20 of 20 cases. Clinical follow-up was available for 56 patients (range, 1-264 months; mean, 57 months). Actuarial analysis of disease-specific survival and relapse-free survival showed that clinical stage was highly statistically significant (P < 0.0001), whereas histologic type and grade approached statistical significance. Multivariate analysis showed that clinical stage was the only significant factor in relapse-free and disease-specific survival.

Helicobacter pylori-associated gastric lymphoma in a girl

We present a case of a 14-year-old girl with gastric large cell lymphoma. The girl's lymphoma was characterized by the presence of mucosa-associated lymphoid tissue. Infection with Helicobacter pylori (HP) was ascertained at the time of diagnosis. The girl was successfully treated by a combination of chemotherapy (MACOP-B) and anti-HP drugs (omeprazole plus amoxicillin). Thrombus of the inferior vena cava, a rare complication, evolved during treatment.

Eradication of Helicobacter pylori and regression of B-cell lymphoma

There is an increasing body of evidence implicating a causal association between Helicobacter pylori and the development of mucosa-associated lymphoid tissue (MALT) associated B-cell gastric lymphoma. Investigators have noted that almost all patients with H pylori-associated chronic gastritis develop lymphoid follicles. Some of these patients demonstrate infiltration of B cells and lymphoepithelial lesions typical of MALT lymphoma. When gastric tissue from patients with gastric B-cell lymphoma is analyzed for H pylori infection, the overwhelming majority of patients demonstrate this condition. Epidemiologic nested case-control studies have shown that patients with gastric non-Hodgkin's lymphoma are substantially more likely that matched controls to have H pylori infection. This situation may be analogous to the linkage between chronic Epstein-Barr virus and lymphoma. The mechanisms inducing the development of lymphoma are not clear, but it has been suggested that chronic infection with H pylori results in the stimulation of H pylori-responsive T cells which in turn activate B cells with the subsequent development of a mutation to a monoclonal B-cell population. Recent evidence indicates that cure of H pylori infection produces regression of MALT lymphoma within 3 to 12 months in approximately 75% of antibiotic-treated patients. Individual responsiveness remains unpredictable, however, and careful and prolonged endoscopic and histologic follow-up is needed. Large, well-controlled studies are necessary, however, to determine the duration of 'cure' and the appropriate setting for treatment.

The significance of B-cell clonality in gastric lymphoid infiltrates

The significance of the demonstration of a clonal B-cell population in gastric lymphoid infiltrates was investigated by analysis of immunoglobulin heavy chain (IgH) gene rearrangements using sensitive polymerase chain reactions, employing fluorescently labelled primers to target the FR3 and FR1 regions. Tissue blocks were studied showing different histological features (high-grade lymphoma, low-grade lymphoma, and chronic gastritis) from 12 gastrectomies for primary gastric lymphoma, together with blocks showing chronic gastritis from 13 cases of gastric adenocarcinoma and biopsies from 33 patients with active Helicobacter-associated chronic gastritis. Clonal IgH gene rearrangements were detected in lymphoma samples from eight of the gastrectomies for lymphoma (67 per cent). In four of these eight specimens, clonal rearrangements were also detectable in the samples showing only chronic gastritis. Three of 28 (11 per cent) informative biopsies showing active Helicobacter-associated chronic gastritis had detectable clonal populations. Clonal rearrangements were also demonstrated in two of eight (25 per cent) informative blocks showing chronic gastritis from eight gastrectomies for adenocarcinoma. It is concluded that the detection of a clonal population in a suspicious lymphoid infiltrate does not confirm the diagnosis of lymphoma, nor does the absence of such a population imply benignity.

Helicobacter pylori infection enhances mucosal interleukin-1 beta, interleukin-6, and the soluble receptor of interleukin-2

It is thought that Helicobacter pylori colonization of the gastric mucosa might stimulate the production of several cytokines, which might trigger and maintain the gastric inflammation associated with Helicobacter pylori infection. In the present study we evaluated interleukin-1 beta. interleukin-6, and the soluble receptor of interleukin-2 both in mucosal homogenates and in the sera of Helicobacter pylori-infected (39 cases) and uninfected (40 cases) patients to investigate whether there was any relationship between variations in cytokines and (1) the severity of Helicobacter pylori-associated gastritis or (2) CagA-positive Helicobacter pylori strains. Mucosal, but not serum levels of interleukins-1 and -6 and interleukin-2 receptor were significantly higher in infected than uninfected patients. Serum levels of Helicobacter pylori antibodies were significantly higher in infected than uninfected patients. These levels correlated with mucosal interleukin-1 beta. The degree of antral or body inflammatory grade was higher in infected than in uninfected patients; cytokines levels were higher in patients with high-grade gastritis, most of whom were Helicobacter pylori positive. Patients infected with CagA-positive strains also had higher levels of interleukin-1 beta, but not of interleukin-2 receptor or interleukin-6. In conclusion. Helicobacter pylori infection results in a local increase in interleukins-1 beta and -6 and interleukin-2 receptor associated with high-grade mucosal inflammation. Interleukin-1 beta seems to favor anti-Helicobacter pylori antibody production, and mucosal levels are enhanced mainly in patients infected with cytotoxic Helicobacter pylori strains.

Gastric juice polymerase chain reaction: an alternative to histology in the diagnosis of Helicobacter pylori infection

BACKGROUND

Infection from Helicobacter pylori plays a role in several gastroduodenal diseases. The recent availability of molecular techniques, particularly the polymerase chain reaction (PCR), allows us to detect small amounts of this bacterium. The aims of this study were to compare PCR and histological findings and to ascertain the clinical usefulness of H. pylori PCR identification in different biological samples.

MATERIALS AND METHODS

We studied 94 consecutive patients. Saliva, gastric juice, and four antral and four body biopsies were obtained from each patient. H. pylori was evaluated histologically in two antral and two body biopsies (Giemsa or Warthin-Starry stain). After extraction, DNA was submitted for PCR amplification using the two primers HPU1 and HPU2, which amplified a 411-bp product from the urease gene A.

RESULTS

Forty-nine patients were H. pylori-positive at histological workup. The sensitivity of PCR was 92% for gastric juice, 73% for antral biopsies, 61% for body biopsies, and 13% for saliva. Of the 45 H. pylori-negative patients at histological assessment, 7 (16%) had positive findings on PCR, mainly when gastric juice was examined.

CONCLUSIONS

These results indicate that PCR is as sensitive as histological assessment. We suggest that PCR H. pylori detection in gastric juice is a sensitive method for diagnosing this infection.

Helicobacter pylori and gastric neoplasia: evolving concepts

There is evidence that Helicobacter pylori infection is associated with gastric cancer and mucosa-associated lymphoid tissue (MALT) lymphoma and possibly with non-ulcer dyspepsia. Eradication therapy for confirmed H. pylori infection may therefore become mandatory in patients with non-ulcer dyspepsia severe enough to warrant endoscopy and in first-degree relatives of patients with gastric cancer. However, routine treatment of asymptomatic carriers awaits confirmation of the association with cancer.

High incidence of other neoplasms in patients with low-grade gastric MALT lymphoma

BACKGROUND

Low-grade gastric MALT lymphoma is an uncommon tumour for which a close association with chronic Helicobacter pylori infection has been suggested. However, given the rarity of MALT lymphoma of the stomach despite the high prevalence of H. pylori infection, it seems plausible that genetic host factors might play a fundamental role in gastric lymphomagenesis.

PATIENTS AND METHODS

We retrospectively reviewed the medical records of 83 patients with low-grade gastric MALT, all of whom resided in a geographic area (southern Switzerland and northern Italy) where the incidence of gastric tumours appears to be uncommonly high.

RESULTS

One or more additional cancers were observed in 17 of 83 patients (20%, 95% CI 12% to 31%) for a total of 23 tumours. Of these, 5 were diagnosed prior to, 12 concomitantly with, and 7 after the gastric MALT lymphoma. Eleven patients had a single additional solid tumour (13%, 95% CI 7% to 22%); 3 patients had non-Hodgkin's lymphoma and one had Hodgkin's disease. Multiple additional cancers were present in 3 cases. Nine of 83 patients have died and 8 of them of a second cancer.

CONCLUSIONS

Unexpectedly an extraordinarily large number of patients with other malignancies was observed in this series. The reasons for this finding are still unknown, but genetic alterations are speculated to play an important role.