Biology and treatment of MALT lymphoma: the state-of-the-art in 1996. A workshop at the 6th International Conference on Malignant Lymphoma. Mucosa-Associated Lymphoid Tissue

MALT lymphoma of the base of the tongue: a rare case entity

Lymphoma is a malignant tumour arising from lymphoid tissue, with the majority of cases being in the lymph nodes, however, in 1/4th of cases, these tumours are found in extralymphoid tissue. Lymphoid tissue is also found in organs having mucosa, such as the digestive tract, salivary gland and in tracheal tissue. This collection of lymphoid tissue is known as mucosa-associated lymphoid tissue (MALT), and non-Hodgkin lymphoma involving this extralymphoidal lymph tissue is known as MALT lymphoma. It was first reported by Isaacson and Wright in 1983, however, it was not included as a working diagnosis in clinical use until it was reclassified as 'marginal zone B-cell lymphoma' in a 1994 Revised European American Lymphoma (REAL) classification. It is rarely seen in the head and neck region, and we report the sixth case of MALT lymphoma of the base of the tongue. A 61-year-old man presented with dysphagia and the feeling of a lump in his throat for 5 months.

Endoscopic ultrasonography for assessment of medical treatment in patients with gastric mucosa‐associated lymphoid tissue lymphoma

Background:  Although gastric mucosa‐associated lymphoid tissue (MALT) lymphoma often regresses after medical treatment, it is not known whether submucosal lymphomatous involvement persists. Because sampling error is a problem associated with histological evaluation and endoscopic ultrasonography (EUS) is appropriate for assessing the depth of infiltration in cases of gastric lymphoma, we investigated the value of EUS for assessing the effectiveness of medical treatment.

Methods:   Twelve patients with gastric MALT lymphoma were treated with Helicobacter pylori eradication therapy and/or chemotherapy. Endoscopic ultrasonography was done at initial staging and after treatment. We used EUS to measure the distance from the surface layer to the deepest part of the hypoechoic area; a distance of less than 1.3 mm was considered normal.

Results:   The mean depth of the hypoechoic area in MALT lymphoma‐positive biopsy specimens was significantly greater than that in MALT lymphoma‐negative biopsy specimens. In many cases in which MALT lymphoma disappeared after treatment, the depth of the endoscopic ultrasonographic hypoechoic area also decreased to normal. In two cases, however, in which the MALT lymphoma biopsy results were negative but there was no decrease to normal depth, recurrence occurred during follow up.

Conclusion:  Our results show that measurement of the depth of the hypoechoic area via EUS is useful in assessing the response of gastric MALT lymphoma to treatment. When the depth of the hypoechoic area does not decrease to normal, careful follow up and frequent biopsies are required.

Mucosa-associated lymphoid tissue lymphoma of the esophagus: a case report

Carcinomas are the most common malignancies of the esophagus. Primary malignant lymphoma involving the esophagus is rare, with only a few cases of mucosa-associated lymphoid tissue (MALT) lymphoma of the esophagus having been reported. We report the case of a 74-year-old man who was diagnosed with an esophageal MALT lymphoma. Generally, MALT lymphomas are indolent and tend to disseminate slowly; however, the behavior of this disease is not known clearly, and a standard treatment has not been established because of its rarity. Although complete response was confirmed with 36-Gy irradiation, careful follow-up is necessary for the patient.

Gastric lymphoma: the revolution of the past decade

BACKGROUND

Gastric MALT type lymphomas are distinct lymphomas that may develop after chronic antigenic stimulation caused by infection with Helicobacter pylori. An early antigen-dependent phase precedes the development of an antigen-independent phase.

METHODS

Narrative review.

RESULTS

The causative relationship between a chronic H. pylori infection and gastric MALT lymphomas has been based on epidemiological, histological, experimental and therapeutic studies. H. pylori eradication leads to a histological remission in +/- 70% of patients in early stage low-grade MALT lymphoma. There is no basis for therapeutic consequences in the case of persistent monoclonality. Full thickness invasion of the gastric wall and lymph node involvement and/or high-grade lymphoma denote the transition to an antigen-independent phase and calls for conventional treatment modalities. Molecular findings show a specific translocation in low-grade MALT lymphomas: t(11,18) and nuclear expression of bcl-10 that are highly indicative of the transition of the antigen-dependent into the antigen-independent phase. Other chromosomal and molecular findings are probably also involved.

CONCLUSION

The multistep pathogenesis of chronic H. pylori gastritis into low-grade gastric MALT lymphoma and tumour progression to a higher stage and grade are characterized by multiple molecular biological events. Antigen-dependency during the early phase of this malignancy is proven by the results of H. pylori eradication.

Differentiation of low-grade gastric MALT lymphoma and high-grade gastric MALT lymphoma: the clinical value of Ga-67 citrate scintigraphy--a pilot study

Ga-67 citrate scintigraphy has been routinely and extensively used to evaluate non-Hodgkin's lymphoma (NHL) for more than 20 years. Gastric lymphoma of mucosa-associated lymphoid tissue (MALT) is by far the most common extranodal primary NHL. Gastric MALT lymphoma can be classified as low-grade (LG) or high-grade (HG). Low-grade gastric MALT lymphoma can be cured by eradication of Helicobacter pylori; but radiotherapy and/or chemotherapy and/or surgery are the major methods of treatment for the HG gastric MALT lymphoma. However, it is difficult to differentiate these two groups by clinical parameters and endoscopic findings. The purpose of this study was to determine whether Ga-67 citrate scintigraphy can distinguish the LG gastric MALT lymphoma from the HG gastric MALT lymphoma. Twenty-one patients (11 men and 10 women ranging in age from 38 to 83 years) with histologically confirmed gastric MALT lymphoma were enrolled. Twelve patients had LG and nine patients had HG. All 21 patients underwent Ga-67 citrate scintigraphy before treatment. The results of Ga-67 citrate scintigraphy were classified as positive or negative. In the LG group, nine patients had negative results and three patients had positive results. In the HG group of nine patients, all patients had positive results. Among the three patients who had positive results in the LG group, the uptake of gastric MALT lymphoma was lower than that of the liver. The Ga-67 citrate scintigraphy is of good clinical value for the differentiation of the LG gastric MALT lymphoma and the HG gastric MALT lymphoma. We think that the major value of Ga-67 citrate scintigraphy will be in following the patients with HG gastric MALT lymphoma after treatment to assess response of therapy and to detect possible recurrence and perhaps in determining transformation from the LG to HG gastric MALT lymphoma. However, further investigation is needed to understand the relationship between the uptake of Ga-67 citrate in gastric MALT lymphoma and transformation.

Low-grade B-cell bronchial associated lymphoid tissue (BALT) lymphoma

Low-grade B-cell bronchial associated lymphoid tissue (BALT) lymphoma is a distinct subgroup of non-Hodgkin's lymphoma. Chronic antigen stimulation, triggered by autoimmune process or persistent infection may precede the development of BALT lymphoma. The lymphoma cells originate from the marginal zone and by invading the bronchial epithelial tissue, give rise to the lymphoepithelial lesion. BALT lymphoma shares the morphologic, immunophenotypic, and cytogenetic characteristics of other mucosa associated lymphoid tissue lymphomas. A majority of the patients are asymptomatic and pulmonary lesions are incidentally discovered on a routine chest radiograph. However, the clinical and radiographic features of BALT lymphoma are nonspecific. The disease is often localized at the time of diagnosis and responds favorably to local treatment, but the optimal management is not clearly defined. Overall, BALT lymphoma has a favorable prognosis and is associated with long-term survival.

Primary low-grade B-cell lymphoma of mucosa-associated lymphoid tissue of the dura mimicking the presentation of an acute subdural hematoma. Case report and review of the literature

The authors present the case of a 64-year-old woman who experienced a left hemiparesis. An initial diagnosis of subdural hematoma was made based on results of computerized tomography scanning. Subsequent magnetic resonance imaging indicated an extraaxial meningioma. Histological findings confirmed an extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT). The authors outline the natural history of central nervous system lymphomas and of MALT lymphomas in other tissues. They review seven previously reported cases and emphasize the importance of recognizing these tumors as a distinct clinicopathological entity.

Complete remission of primary high-grade B-cell gastric lymphoma after cure of Helicobacter pylori infection

PURPOSE

Treatment of low-grade gastric mucosa-associated lymphoid tissue lymphoma by eradication of Helicobacter pylori is reported to result in complete lymphoma remission in approximately 75% of cases. The effect that cure of the infection has on the course of a primary high-grade gastric lymphoma is largely uncertain. The aim of this study was to report the effect of cure of H pylori infection exerted in patients with high-grade B-cell gastric lymphoma.

PATIENTS AND METHODS

Eight patients (4 males and 4 females; age range, 26 to 85 years) with H pylori infection and high-grade lymphoma received eradication therapy before planned treatment. The effect of H pylori eradication on the course of high-grade lymphoma was assessed by analysis of surgical specimens (n = 2) or endoscopic biopsies (n = 6).

RESULTS

H pylori eradication was successful in all patients and led to complete remission of the lymphoma in seven patients. One patient has experienced partial remission. Two patients were referred to surgery, one of whom (stage II(1E)) had lymph node involvement, and the histologic work-up of the resected stomach revealed residual infiltrates of a low-grade lymphoma, which prompted consolidation chemotherapy. In one patient (initially stage I(1E)), abdominal lymphoma developed 6 months after eradication therapy, which regressed completely after chemotherapy. In four patients, no further treatment was given. Six patients continue in complete remission (range, 6 to 66 months).

CONCLUSION

Primary high-grade B-cell gastric lymphoma in stages I(E) through II(E1) associated with H pylori may regress completely after successful cure of the infection. Prospective trials are needed to investigate this treatment in larger numbers of patients.

Malignant tumors of the stomach. Gastric mucosa-associated lymphoid tissue lymphoma and Helicobacter pylori

With the help of many clinical studies, the diagnosis and therapy of gastric MALT lymphoma have evolved. Major progress has been seen in this area, including improvement of biopsy diagnosis, better histologic classification, new information concerning pathogenesis, and, especially, the start of a revolution in the treatment of low-grade gastric MALT lymphomas by eradicating H. pylori. About 12 clinical studies with almost 400 patients and case reports have shown that cure of H. pylori infection is associated with complete remission in approximately 80% of patients with low-grade MALT lymphoma in an early clinical stage. To establish H. pylori eradication as the primary choice in low-grade gastric MALT lymphoma further, it is necessary to select patients before therapy who are most likely to benefit from this single treatment modality. An excellent histologic workup of obtained biopsy specimens and comprehensive clinical staging are necessary. Because of the supposition that H. pylori-related growth support may play a role only in the early stages of low-grade gastric MALT lymphoma, the importance of determining the depth of lymphoma infiltration in the gastric wall is evident. Examinations by endosonographic ultrasonography have been shown to be the most reliable method to differentiate the layers of the gastric wall and to determine the infiltration depth of lymphomas. Eradication of H. pylori has to be considered as a first-line and single treatment modality in patients with low-grade gastric MALT lymphoma in clinical stage EI1. As a therapy with fewer side effects than radiation, surgery, or chemotherapy and as a stomach-conserving treatment, eradication of H. pylori in patients with low-grade gastric MALT lymphoma should be the treatment of the choice within clinical trials because there are no long-term results available thus far. Besides pretreatment patient selection, careful follow-up with endoscopy, biopsies, and clinical staging including endoscopic ultrasonography is necessary. A 5- to 10-year follow-up is necessary before the definitive value of H. pylori eradication can be established, but long-term results are excellent thus far. There are many questions to be addressed: What are the exact mechanisms that lead to the malignant transformation of a reactive infiltrate? Why do approximately 20% of low-grade MALT lymphomas not regress after H. pylori eradication? Is there a molecular-genetic or immunologic point of no return? What is the biologic significance of the immunoglobulin rearrangement detected with PCR? What will be the 5- and 10-year relapse-free survival rates of patients suffering from low-grade MALT lymphoma treated with H. pylori eradication alone as first and only treatment? The wave of new data each year about the role of H. pylori in gastric MALT lymphoma may help many of these questions to be answered.

Incidence and subtype specificity of API2-MALT1 fusion translocations in extranodal, nodal, and splenic marginal zone lymphomas

The t(11;18)(q21;q21) is thought to represent an important primary event in the development of marginal zone lymphomas, although an accurate estimation of the frequency and distribution of this genetic alteration among nodal, splenic, and extranodal marginal zone lymphoma types has yet to be determined. Recently, molecular genetic studies have shown that this translocation results in the fusion of the API2 gene on chromosome 11 and a novel gene termed MALT1 on chromosome 18. To investigate the incidence of API2-MALT1 fusion transcripts among marginal zone lymphomas and to determine possible marginal zone lymphoma subtype associations, we used reverse transcriptase-polymerase chain reaction to analyze RNAs extracted from frozen tissue samples of 99 marginal zone lymphomas. Fifty-seven involved diverse extranodal sites including 14 stomach, 11 lung, 7 orbit, 7 parotid, 5 thyroid, 5 lacrimal gland, 3 small intestine, 2 large intestine, 1 kidney, 1 paraspinal region and 1 skin. Twenty-one primary splenic and twenty-one primary nodal marginal zone lymphomas were also studied. API2-MALT1 fusion transcripts were detected in 12 of 57 extranodal marginal zone lymphomas (21%), but in none of the nodal or splenic cases. The cDNA sequences of the fusion transcripts were determined, revealing variation in the coding sequence fusion point for both API2 and MALT1. The findings suggest that t(11;18)(q21;q21) is restricted to extranodal marginal zone lymphomas and that these tumors have distinct genetic etiologies in comparison with their splenic and nodal counterparts.

Detection of aberrant isotype switch recombination in low-grade and high-grade gastric MALT lymphomas

Gastric mucosa-associated lymphoid tissue (MALT) lymphoma originates from reactive lymphocytic infiltrates during chronic gastritis, closely associated with Helicobacter pylori infection. MALT lymphomas may be either “low grade” or “high grade,” and transformation from low grade to high grade can occur. To obtain information on the maturational state of MALT lymphoma cells, we investigated their ability to undergo isotype switch recombination, which together with immunoglobulin variable gene somatic mutation, contributes to normal B-cell maturation. Using specific probes for the immunoglobulin heavy-chain (IgH) switch regions, we found by Southern blot that 3 out of 5 low-grade cases and 2 out of 2 high-grade cases showed rearrangements within IgH switch regions, which appeared aberrant in 4 of the 5 cases. The cloning of two rearranged fragments from one low-grade and one high-grade case confirmed the aberrant nature of the rearranged fragments. A deletion from the switch μ region (Sμ) to the first constant μ exon (Cμ 1) and a second deletion from the second constant μ exon (Cμ 2) to the gamma 3 region (γ 3) was detected in the low-grade case. In the high-grade case, there was a deletion of the IgH intronic enhancer (Eμ) and a 336–base pair (bp) insertion into the Sμ region of a gene (KIAA0307) normally located at 15q24. These data demonstrate for the first time the ability of MALT lymphoma cells to undergo aberrant isotype switch recombinations, which might be directly involved in the development or progression of malignancy.

MALT lymphoma of nasal mucosa treated with antibiotics

Mucosa associated lymphoid tissue (MALT) lymphomas occur in sites other than the gastrointestinal tract and in the early stages respond to treatment with antibiotics. We report a rare case of nasal mucosal MALT lymphoma which responded to treatment with antibiotics and has since then remained in remission.

Molecular genetics of extranodal marginal zone (MALT-type) B-cell lymphoma

Mucosa-associated lymphoid tissue lymphoma is now classified as extranodal marginal zone B-cell lymphoma. We reviewed the current literature on the biological and genetic mechanisms that lead to the development and progression of this unusual lymphoma. Particular attention was given to the clinical and biological significance of the immunoglobulin genes rearrangement, that has been proposed and widely used both diagnostically and as a tool to monitor the response to antibiotic treatment.

Primary non-Hodgkin's lymphoma of the nasal cavity: prognostic significance of paranasal extension and the role of radiotherapy and chemotherapy

BACKGROUND

This study was conducted to determine whether the paranasal extension of a primary non-Hodgkin's lymphoma (NHL) of the nasal cavity has any deleterious effect on patient outcome.

METHODS

One hundred and seventy-five patients with previously untreated nasal NHL were reviewed. There were 2 with low grade, 107 with intermediate grade, 17 with high grade, and 49 with unclassifiable lymphomas. In 48 cases the immunophenotype was available and 46 were T-cell lymphoma. According to the Ann Arbor system, there were 133 patients with Stage IE, 28 with Stage IIE, 4 with Stage IIIE, and 10 with Stage IVE lymphomas. Stage IE was subdivided into limited Stage IE (i.e., confined to the nasal cavity [67 patients]) or extensive Stage IE (i.e., presenting with extension beyond the nasal cavity [66 patients]). For patients with limited Stage IE disease the treatment of choice was radiotherapy with or without chemotherapy. In patients with extensive Stage IE disease, treatment was comprised of a combination of chemotherapy and radiotherapy or radiotherapy alone. For patients with a more advanced stage of disease (IIE-IVE), chemotherapy was an integral part of the treatment and was completed by irradiation, especially for patients with Stage IIE disease.

RESULTS

The actuarial overall survival (OS) and disease free survival (DFS) rates at 5 years for the whole group were 65% and 57%, respectively. The 5-year OS and DFS rates were influenced by stage, with a gradual decrease from 75% and 68% for Stage IE disease to 35% and 28% for Stage IIE disease, and 31% and 19% for Stage IIIE/IVE disease. Patients with limited Stage IE disease survived significantly longer (90% 5-year OS) compared with those with extensive Stage IE disease (57% 5-year OS; P < 0.001). For 67 patients with limited Stage IE disease, the 5-year OS was 89% with radiotherapy alone and 92% with radiotherapy and chemotherapy, whereas for 66 patients with extensive Stage IE disease, the 5-year OS was 54% with radiotherapy and 58% with combined modality therapy or chemotherapy (P > 0.05).

CONCLUSIONS

The prognosis of patients with primary NHL of the nasal cavity is stage dependent. In this large cohort of Stage IE patients, it was demonstrated that the paranasal local extension was a significant prognostic factor associated with poorer treatment outcome. The authors believe that Ann Arbor Stage IE should be subclassified further into limited and extensive Stage IE. The addition of chemotherapy did not appear to modify significantly the survival of patients with either limited or extensive Stage IE disease. The extranodal progression observed in patients with extensive Stage IE and Stage IIE-IVE disease clearly illustrates the need for improvement of systemic treatment.

Characteristic Pattern of Chromosomal Gains and Losses in Primary Large B-Cell Lymphomas of the Gastrointestinal Tract

In contrast to low-grade B-cell lymphomas originating in the gastrointestinal (GI) tract, only few cytogenetic data are available for the large cell, highly malignant variants. We studied 31 large B-cell lymphomas of the GI tract by comparative genomic hybridization (CGH) and fluorescence in situ hybridization using specific DNA probes (FISH). The most frequent aberrations were gains of all or of parts of chromosomes 11 (11 cases), 12 (9 cases), 1q (4 cases), and 3q (4 cases). Losses of parts of chromosome 6q and of parts of the short arm of chromosome 17 (6 cases each) were found most frequently. In four cases a total of seven high-level DNA amplifications was detected. In two of these cases, involvement of specific protooncogenes (RELand MYC) was shown. Some genetic aberrations seemed to be associated with an inferior clinical course: patients with ≥2 aberrations had a significantly shorter median survival. Furthermore, all patients with gains of all or parts of chromosome arm 1q and with high-level DNA amplifications as well as seven of nine patients with gains of all or parts of chromosome 12 died of lymphoma. In conclusion, the pattern of chromosomal gains and losses in large B-cell lymphomas was different from data reported for low-grade (MALT) lymphomas of the stomach and bowel, especially with respect to the high incidence of partial gains of chromosome arm 11q and of all or parts of chromosome 12 and the low frequency of polysomy 3. In addition, our data suggest that chromosomal gains and losses detected by CGH and FISH may predict for the outcome of patients with this tumor entity.

Characteristic Pattern of Chromosomal Gains and Losses in Primary Large B-Cell Lymphomas of the Gastrointestinal Tract

In contrast to low-grade B-cell lymphomas originating in the gastrointestinal (GI) tract, only few cytogenetic data are available for the large cell, highly malignant variants. We studied 31 large B-cell lymphomas of the GI tract by comparative genomic hybridization (CGH) and fluorescence in situ hybridization using specific DNA probes (FISH). The most frequent aberrations were gains of all or of parts of chromosomes 11 (11 cases), 12 (9 cases), 1q (4 cases), and 3q (4 cases). Losses of parts of chromosome 6q and of parts of the short arm of chromosome 17 (6 cases each) were found most frequently. In four cases a total of seven high-level DNA amplifications was detected. In two of these cases, involvement of specific protooncogenes (RELand MYC) was shown. Some genetic aberrations seemed to be associated with an inferior clinical course: patients with ≥2 aberrations had a significantly shorter median survival. Furthermore, all patients with gains of all or parts of chromosome arm 1q and with high-level DNA amplifications as well as seven of nine patients with gains of all or parts of chromosome 12 died of lymphoma. In conclusion, the pattern of chromosomal gains and losses in large B-cell lymphomas was different from data reported for low-grade (MALT) lymphomas of the stomach and bowel, especially with respect to the high incidence of partial gains of chromosome arm 11q and of all or parts of chromosome 12 and the low frequency of polysomy 3. In addition, our data suggest that chromosomal gains and losses detected by CGH and FISH may predict for the outcome of patients with this tumor entity.

Non-Hodgkin lymphoma during pregnancy

The authors report a case of a pregnancy with a Non-Hodgkin lymphoma. A histological association of high-grade B-cell and a MALT type lymphoma was found which, to their best knowledge, is described for the first time in pregnancy.

Gastric lymphoma of mucosa-associated lymphoid tissue and Helicobacter pylori

Although the majority of primary gastric lymphomas are of high-grade non-Hodgkin's type, a significant number are low-grade B cell lymphomas. The recognition that the majority of the latter have characteristic clinicopathological features that are different from those of their nodal counterparts has led to the suggestion that these lymphomas arise specifically from within organized extranodal lymphoid tissue; this tissue resembles that seen constitutively in the intestine (mostly located in the terminal ileum as Peyer's patches) and is termed mucosa-associated lymphoid tissue (MALT). The paradox of this proposal is that there is no MALT in the gastric mucosa in normal individuals from which a primary lymphoma can arise. However, it has been shown that organized lymphoid tissue with all the features of MALT can be acquired in the gastric mucosa, and this is seen most frequently, but not exclusively, in association with infection by Helicobacter pylori (H. pylori). Subsequent studies have confirmed a close association between H. pylori infection and gastric MALT lymphoma with the infection preceding the development of the lymphoma. In vitro studies have demonstrated that there is an immunologically based drive to tumor cell proliferation in low-grade gastric MALT lymphomas associated with the presence of H. pylori. Clinical studies have shown that, at least in early lesions, eradication of the organism can result in tumor regression in 60 to 92% of cases.

Low-grade B cell lymphoma of mucosa-associated lymphoid tissue in the thymus of a patient with rheumatoid arthritis

The majority of thymic lymphomas are either lymphoblastic lymphoma, large B cell lymphoma or Hodgkin's disease, and other types of non-Hodgkin lymphoma are rare. A case of low-grade B cell lymphoma of mucosa-associated lymphoid tissue (MALT) in the thymus is reported. A 55-year-old Japanese female with a history of rheumatoid arthritis (RA) complained of back pain. A mediastinal tumor was identified by computerized tomography and magnetic resonance imaging, and the thymus was resected through median sternotomy. The solid and nodular tumor had several small satellite extensions and was completely confined to within the thymus. Histologically, monotonous medium-sized centrocyte-like cells occupied the medulla of the thymus and infiltrated Hassall's corpuscles (lymphoepithelial lesions). Immunohistochemically, tumor cells were positive for CD20 and CD79a. IgA and kappa light chain restriction were also found in plasmacytoid cells in the tumor. Clonal rearrangement of the immunoglobulin heavy chain gene was demonstrated by polymerase chain reaction. This case was diagnosed as MALT-type low-grade B cell lymphoma in the thymus. This is the first report of low-grade B cell lymphoma in the thymus associated with RA. As autoimmune diseases are known to be associated with lymphoid neoplasms, it is suggested that the RA played an important role in the development of malignant lymphoma in this case.

Overview of treatment of localized low-grade lymphomas

The results of treatment of localized low-grade lymphoma have been reviewed with particular emphasis on the results of long-term follow-up of patients treated with radiation therapy at Stanford University. These data and results from numerous other centers suggest that 40% to 50% of patients with stage I and II follicular low-grade lymphomas can expect to achieve clinical cure of their disease with radiation therapy. Randomized trials published to date do not support the use of adjuvant chemotherapy. Although a policy of initial observation with deferral of treatment until the occurrence of disease progression is a well established approach to patients with advanced disease, no randomized studies exist that support this as a safe alternative to radiation therapy for early stage disease. New systemic therapies are required for the treatment of occult disease to prevent the occurrence of relapse outside of irradiated volumes.

Clinical features, treatment and outcome in a series of 93 patients with low-grade gastric MALT lymphoma

The purpose of this paper is to report the clinical characteristics and treatment outcome following different therapeutic approaches in a large series of patients with primary low-grade MALT lymphoma of the stomach. A total of ninety-three patients (median age 63 years) were reviewed. The patients were treated by different modalities (local treatment alone, combined treatment, chemotherapy, antibiotics alone); seven patients refused any treatment. The antibiotic-treated group of patients was prospectively followed with regular endoscopic biopsies, and their responses were histologically evaluated. The 5-years projected overall survival is 82% (95% C.I.; 67%-91%) in the series as a whole. Second tumors were observed in 21.5% of the patients in this series (95% CI 14%v to 31%). There was no apparent difference in overall survival and event-free survival between patients who received different treatments. In the antibiotic-treated group histologic regression of MALT lymphoma was documented in 67% of patients (95% CI 51% to 80%). In conclusion the indolent nature of the disease justifies a conservative approach. The use of antibiotics as first-line therapy may avert or at least postpone the indication for surgical resection in the majority of patients.