Estimating the prevalence of Epstein-Barr virus in primary gastric lymphoma: a systematic review and meta-analysis

The stomach is a common site for extranodal non-Hodgkin's lymphoma. While Helicobacter pylori (H. pylori) is the main established risk factor for primary gastric lymphoma, a fraction could be aetiologically associated with Epstein-Barr virus (EBV), a known haematolymphoid carcinogen. We systematically searched five databases from 1 January 1990 until 31 May 2022 for studies reporting EBV prevalence in gastric lymphoma tumour tissue by in-situ hybridisation (ISH) for EBV-encoded small RNA (PROSPERO CRD42020164473). We included representative series of more than five gastric lymphoma cases. Pooled prevalence and corresponding 95% confidence intervals (CI) of EBV in gastric tumour cells were calculated for two major gastric B-cell lymphoma types, mucosa-associated lymphoid tissue (MALT) lymphoma and diffuse large B-cell lymphoma (DLBCL). When available, we also extracted data on H. pylori prevalence and survival by EBV status. We found ten studies including 194 cases of gastric MALT lymphoma and 11 studies including 643 cases of gastric DLBCL. EBV prevalence was 2.2% (95% CI: 0.5-13.3) in gastric MALT lymphoma and 11.0% (95% CI: 5.2-20.0) in gastric DLBCL. In a subset of studies, the prevalence of H. pylori was higher in gastric MALT lymphoma (51/69) compared to gastric DLBCL (62/102). Overall, our findings suggest that EBV is rarely seen in MALT lymphoma but is associated with around 10% of gastric DLBCL, similar to the proportion observed at other primary sites. EBV-related lymphoma adds a small number of cases to the burden of cancer that could be prevented by the future development of a vaccine against EBV.

A viral map of gastrointestinal cancers

Cancers of the gastrointestinal tract (GIT) are expected to account for approximately 20% of all cancers in 2017. Apart from their high incidence, GIT cancers show high mortality rates, placing these malignancies among the most prominent public health issues of our time. Cancers of the GIT are the result of a complex interplay between host genetic factors and environmental factors and frequently arise in the context of a continued active inflammatory response. Several tumor viruses are able to elicit such chronic inflammatory responses. In fact, several viruses have an impact on GIT tumor initiation and progression, as well as on patients' response to therapy and prognosis, through direct and indirect mechanisms. In this review, we have gathered information on different viruses' rates of infection, viral-driven specific carcinogenesis mechanisms and viral-related impact on the prognosis of cancers of the GIT (specifically in organs that have an interface with the environment - esophagus, stomach, intestines and anus). Overall, while some viral infections show a strong causal relation with specific gastrointestinal cancers, these represent a relatively small fraction of GIT malignancies. Other types of cancer, like Esophageal Squamous Cell Carcinoma, require further studies to confirm the carcinogenic role of some viral agents.

Treatment of gastric mucosa-associated lymphoid tissue lymphoma: Helicobacter pylori eradication and beyond

Gastric mucosa-associated lymphoid tissue (MALT) lymphoma is the paradigm of lymphomas developing in extranodal areas after antigen stimulation. In the stomach, Helicobacter pylori colonization induces the appearance of MALT and, eventually, MALT-derived lymphoma. This type of lymphoma is initially a localized form of disease, but may disseminate and transform into high-grade lymphoma, making full staging (as for nodal lymphomas) and endoscopic ultrasonography to evaluate the penetration of the lymphoma through the gastric wall mandatory. In localized gastric MALT lymphoma, the first step in treatment is eradication of H. pylori, which results in 60-90% regression. This response is maintained for years in most patients, with only 10-15% relapse, frequently precipitated by H. pylori reinfection. A component of high-grade lymphoma, penetration to gastric serosa or beyond and translocation t(11;18) are the main factors that make lymphoma resistant to eradication. Surgery or radiotherapy can cure localized lymphomas in 75-90% of patients. Chemotherapy with alkylating agents, combination chemotherapy and purine analogs, and anti-CD20 antibodies can also induce remission of localized lymphomas refractory to eradication, as well as locally advanced and disseminated lymphomas. The optimum chemotherapy treatment for advanced disease has not yet been established; however, combination therapy, including purine analogs with or without anti-CD20, may be a promising option. Despite histological responses and prolonged remissions, residual molecular disease can be demonstrated in most cases treated with H. pylori eradication, radiotherapy or alkylating agents, and even after more intense chemotherapy, although this does not seem to lead to late relapses. High-grade gastric MALT lymphoma should be treated with chemotherapy, with cyclophosphamide, doxorubicin, oncovin and prednisone being the best first-line option. All gastric MALT lymphomas associated with H. pylori should receive eradication treatment in addition to other required treatment.

Incidence of gastric B-cell lymphomas: a population-based study in Germany

BACKGROUND

While the clinical and experimental knowledge concerning gastric lymphomas is increasing, there is a scarcity of epidemiological data.

PATIENTS AND METHODS

A population-based sample of patients in Franconia and Saarland in Germany was collected from a clinical trial, hospital archives and a cancer registry.

RESULTS

Over a period of 3 years, 94 patients with primary gastric lymphoma were recorded out of a total population of 3.5 million. The standardised incidence rates in Saarland and Franconia were 0.7 and 0.8 cases per 100 000, respectively. Patients were predominantly from higher age groups (mean age 62.1 years) and the incidence in men was slightly more than in women (P <0.03). The distribution of histological subtypes in Franconia was as follows: marginal zone B-cell lymphomas (MZBL), 58%; diffuse large-cell B-cell lymphoma (DLBL), 33%; and mixed forms, 9%. Helicobacter pylori could be detected histologically in 84% of all cases, 95% of MZBL cases and 68% of DLBL cases.

CONCLUSIONS

Incidence rates of gastric lymphoma in Germany were similar to that in other European countries, except England, where rates are lower. The subtype-specific differences of H. pylori infection rates could be due to differences in carcinogenesis or to secondary changes during malignant transformation.

Gastrointestinal lymphoma: prevention and treatment of early lesions

Gastrointestinal lymphomas comprise a group of distinct clinicopathological entities. Differences in lifestyle and environmental factors between countries could account for the variety in the distribution of the main subtypes: low-grade B-cell lymphomas of the mucosa-associated lymphoid tissue type, alpha-chain disease and enteropathy (coeliac disease)-associated T-cell lymphoma (EATL). The possibility of preventing these lymphomas implies a knowledge of their natural history together with an identification of potential predisposing factors. The development of the lymphoid hyperplasia and subsequently low-grade lymphoma with the possibility of high-grade transformation is a multifactorial process involving both antigenic and host-related factors. The pathogenic role of Helicobacter pylori and gluten has been demonstrated in gastric lymphoma and enteropathy-associated T-cell lymphoma respectively, while environmental factors, especially non-specific bacterial ones, may play a major role in the pathogenesis of alpha-chain disease. The most difficult task in preventing these lymphomas is the recognition of early lesions likely to regress after the removal of the exogenous stimulus.

A critical review of the effect of Helicobacter pylori eradication on gastric MALT lymphoma

Low-grade B-cell lymphomas of mucosa-associated lymphoid tissue (MALT) are thought to arise within organized lymphoid tissue in the gastric mucosa that is most frequently acquired in response to Helicobacter pylori infection. This close association between the organism and the lymphoma is further reflected by the demonstration that the proliferation of the lymphoma cells can be driven by the presence of H. pylori organisms through a complex path of cellular interactions involving specific T cells. From these observations it was suggested that removal of one of the proliferative drives to the neoplastic cells in the form of eradication of the organism might induce a remission in the tumor. Several large multicenter studies are now underway to consider this question, and interim reports suggest that long-term remissions can be induced in low-grade MALT lymphomas in 70% to 80% of cases. The lymphomas that are most likely to respond to H. pylori eradication are those that are located superficially within the gastric mucosa. It has been suggested that certain genetic abnormalities, such as t(11;18) and the Bcl-10 mutation, may be associated with lack of response to this therapy. Recurrences of low-grade lymphoma are encountered in patients treated by H. pylori eradication, but these appear to be infrequent and may be self-limiting and spontaneously regress without further therapy.

Incidence of second neoplasms in patients with MALT lymphoma: no increase in risk above the background population

BACKGROUND

Lymphomas of mucosa associated lymphoid tissue (MALT) are a special type of extranodal lymphoma, possibly related to chronic antigenic stimulation. Increased cancer susceptibility may also contribute to the development of MALT lymphoma (MALToma). It has been suggested that patients with MALToma have an increased incidence of other malignancies.

PATIENTS AND METHODS

We retrospectively reviewed the histology and clinical records of 147 patients with MALToma, including 51 cases of gastric MALToma. The incidence of any second malignancy was confirmed with a provincial registry. The relative rates of cancer, excluding MALToma, were calculated relative to the background population of the same age group and secular year.

RESULTS

A total of 41 tumors occurred in 32 patients (21%), including 22 solid tumors. The incidence of solid tumors in the gastric MALToma group was 15%. Seven patients had two or more second malignancies. Cancer occurred before diagnosis of MALToma in 29 cases, concurrent with MALToma in three, and after MALToma in nine. Follow-up of the surviving patients is short (median 17.6 months). The relative rate from birth of a second malignancy was 0.86 in the whole group (90% confidence interval (CI): 0.62-1.16) and 0.95 (90% CI: 0.55-1.54) in the gastric MALToma group. The rates were roughly the same if skin cancers were excluded.

CONCLUSIONS

The incidence of second cancers in this series is similar to previous reports. However, when compared to an age-matched population followed for the same period of time, MALToma patients do not appear to have a statistically significant increased rate of cancers.

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.

Epstein-Barr virus infection and its gene expression in gastric lymphoma of mucosa-associated lymphoid tissue

The role of Epstein-Barr virus (EBV) in the pathogenesis of gastric lymphoma of mucosa-associated lymphoid tissue (MALT) has not been well understood. The aim of the study was to investigate EBV infection and its gene expression in this tumor in order to understand its role in the pathogenesis. EBV infection was screened by in situ hybridization for EBV-encoded non-polyadenylated RNA (EBER ISH) in 79 cases of gastric MALT lymphoma of nonimmunocompromised patients. The expression of EBV proteins [LMP1 (latent membrane protein 1), EBNA2 (EBV nuclear antigen 2), ZEBRA (switch protein encoded by BZLF1 gene)] was studied by immunohistochemistry in EBER-positive cases. EBV was detected with EBER ISH in 15 (19%) of the 79 cases. EBV was found in virtually all tumor cells in 2 cases of high-grade MALT lymphoma (2.5%) (EBV-associated), and was found only in occasional large or small lymphoid cells in 13 cases (16.5%). False positive EBER signal was detected in the mucinous glandular epithelial cells of gastric antrum with FITC-labeled oligonucleotide probe but not with digoxigenin or 35S-labeled riboprobes. Type II latency (EBER+LMP1+ EBNA2-) was detected in both EBV-associated cases. Type III latency (EBER+LMP1+EBNA2+) was also identified in one EBV-associated case besides latency II. Double labeling showed coexpression of LMP1 and EBNA2 in a small number of tumor cells, indicating the presence of type III latency in single cell level. In cases with only occasional EBER-positive large or small lymphoid cells, LMP1 and EBNA2 were not detected. ZEBRA was negative in all the cases. These findings suggest that EBV may contribute to the pathogenesis of a small proportion of high-grade MALT lymphoma, where virtually all tumor cells harbored EBV and the oncogenic viral protein LMP1 was expressed. Moreover, latency III of EBV infection may exist in nonimmunocompromised patient.

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.