Comparable Efficacy of Reduced Dose Radiation Therapy for the Treatment of Early Stage Gastric Extranodal Marginal Zone Lymphoma of Mucosa-Associated Lymphoid Tissue

Marginal zone lymphoma: 2023 update on diagnosis and management

DISEASE OVERVIEW

Marginal zone lymphomas (MZL) are collectively the second most common type of indolent lymphoma.

DIAGNOSIS

Three subtypes of MZL are recognized: splenic, extranodal, and nodal. The diagnosis is secured following biopsy of an involved nodal or extranodal site demonstrating a clonal B-cell infiltrate with CD5 and CD10 negative immunophenotype most common. Some cases will features IgM paraprotein, but MYD88 L256P mutations are less frequent than in Waldenstrom macroglobulinemia. Prognostication Several prognostic models have been developed, including the MALT-IPI and the MZL-IPI. The latter is broadly applicable across MZL subtypes and incorporates elevated serum LDH, anemia, lymphopenia, thrombocytopenia and nodal or disseminated subtypes as independent predictors of outcome.

TREATMENT

We discuss suggested approach to therapy for both early and advanced-stage disease, with reference to chemo-immunotherapy, radiotherapy, and emerging treatments in relapsed/refractory disease such as BTK inhibitors.

Enhancing prognostication and personalizing treatment of extranodal marginal zone lymphoma

INTRODUCTION

Extranodal marginal zone lymphoma (EMZL) of mucosa-associated lymphoid tissue is an indolent lymphoma originating from marginal zone B-cells and associated with chronic inflammation. EMZL demonstrates distinct genomic alterations according to the primary extranodal site of disease but commonly affects signaling pathways including NF-ĸB, B-cell receptor, and NOTCH. Treatment with radiation therapy is commonly implemented in localized diseases, and multiple agents are available for patients with advanced-stage diseases in need of therapy. Bendamustine with rituximab is a frontline platform associated with high efficacy.

AREAS COVERED

Clinical features, diagnosis, genomics, models enabling risk stratification, treatment options, and future directions.

EXPERT OPINION

The lack of consistent genotyping profile in EMZL precludes the development of tissue and circulatory biomarkers for the diagnosis, risk stratification, and monitoring of minimal residual disease. Furthermore, the biological heterogeneity observed in extranodal sites associated with overall limited genomic data prevents the testing of druggable pathways aiming for a personalized treatment approach. Future clinical trials should focus on EMZL considering the unique clinical characteristics in the eligibility criteria and response assessment to better inform efficacy of novel agents and delineate sequences of therapies.

Risk of Diabetes Mellitus after Radiotherapy for Gastric Mucosa-Associated Lymphoid Tissue Lymphoma

The long-term effect of radiation on the pancreas in pediatric patients has been studied without individual radiation dosimetric data. This study investigated the effect of radiotherapy on the risk of developing diabetes mellitus (DM) in patients with gastric mucosa-associated lymphoid tissue lymphoma (GML), using individual radiation dosimetric analysis. Retrospective analysis reviewed the data of 225 patients without a history of DM receiving curative treatment for stage IE GML. Involved-site radiotherapy was delivered to the whole stomach in 83 patients. The pancreas was delineated in each patient’s computed tomography scan for dosimetric analysis. At a median follow-up of 49.0 months, the 5-year cumulative incidence of DM was 4.5%, 9.6%, and 1.6% in all patients, patients who received radiotherapy, and patients who did not receive radiotherapy, respectively (p = 0.009). Mean pancreatic dose (Dmean; p = 0.009), sex (p = 0.043), and body mass index (BMI; p = 0.008) were independently associated with DM. Using recursive partitioning analysis, patients were classified into low, intermediate, and high-risk groups, with 5-year DM incidence rates of 0.0%, 3.1%, and 15.6%, respectively (p < 0.001). Incidental irradiation of the pancreas can increase the risk of DM, which may be stratified according to patient sex and BMI.

Does endoscopic submucosal dissection have its place in the treatment of patients with gastric mucosa associated lymphoid tissue lymphoma localized disease after eradication?

Mucosa associated lymphoid tissue (MALT) lym- phoma, one of the B-cell non-Hodgkin’s lymphoma, always occurs in the extranodal margin zone. Gastric MALT lymphoma, has attracted attention because of its relationship with Helicobacter pylori (H. pylori). H. pylori eradication was considered as the first-line treatment regardless of stages and H. pylori status in the latest review (1). As for patients with localized disease who failed response after H. pylori eradication, radiotherapy was suggested, but is there a place for endoscopic treatment in such patients remains open to debate.

Development of Organ-Preserving Radiation Therapy in Gastric Marginal Zone Lymphoma

Simple Summary

Gastric marginal zone lymphoma of the stomach is a rare cancer type primarily treated with oral proton pump inhibitors. If the disease does not respond to this, radiation is the treatment of choice. This review presents the development of radiation therapy over the last decades. Earlier, the stomach was surgically removed and irradiation was performed using large-field techniques and high doses of radiation. Currently, the standard treatment is the use of small-volume radiation therapy (with few side effects) with the preservation of the stomach, which provides excellent outcomes. In addition, this paper provides an outlook on current studies and possible future developments.

Abstract

Gastric marginal zone lymphoma (gMZL) of mucosa-associated lymphoid tissue (MALT) may persist even after H. pylori eradication, or it can be primarily Helicobacter pylori (H. pylori) independent. For patients without the successful eradication of lymphoma, or with progressive disease, treatment options have historically included partial or total gastrectomy. Presently, in these instances, curative radiation therapy (RT) is the current standard of care. This review emphasizes the historically changing role of radiation therapy in gMZL, progressing from large-volume RT without surgery, to localized RT, on its own, as a curative organ-preserving treatment. This overview shows the substantial progress in radiation therapy during the recent two to three decades, from high-dose, large-field techniques to low-dose, localized target volumes based on advanced imaging, three-dimensional treatment planning, and advanced treatment delivery techniques. RT has evolved from very large extended field techniques (EF) with prophylactic treatment of the whole abdomen and the supradiaphragmatic lymph nodes, applying doses between 30 and 50 Gy, to involved-field RT (IF), to the current internationally recommended involved site radiation therapy (ISRT) with a radiation dose of 24–30 Gy in gMZL. Stage-adapted RT is a highly effective and safe treatment with excellent overall survival rates and very rare acute or late treatment-related toxicities, as shown not only in retrospective studies, but also in large prospective multicenter studies, such as those conducted by the German Study Group on Gastrointestinal Lymphoma (DSGL). Further de-escalation of the radiation treatments with low-dose 20 Gy, as well as ultra-low-dose 4 Gy radiation therapy, is under investigation within ongoing prospective clinical trials of the International Lymphoma Radiation Oncology Group (ILROG) and of the German Lymphoma Alliance (GLA).