How do I treat gastric localized Mucosa-Associated Lymphoid Tissue (MALT) lymphoma?

Treatment of Localized Gastric MALT Lymphoma

For localized gastric MALT lymphoma, Helicobacter pylori eradication therapy should be the sole initial treatment regardless of H. pylori status, followed by radiotherapy for non-responders. 1

Initial Diagnostic Workup

• Endoscopic evaluation: Esophagogastroduodenoscopy with multiple biopsies from each region of stomach, duodenum, gastroesophageal junction and any abnormal sites 1
• Endoscopic ultrasound: Essential to evaluate regional lymph nodes and gastric wall infiltration 1
• H. pylori testing: Multiple methods should be used:
  • Histochemistry on gastric biopsies
  • Urea breath test
  • Stool antigen test
  • Serology
• Molecular testing: FISH or PCR for t(11;18)(p21;p21) translocation to identify patients unlikely to respond to antibiotics 1
• Staging workup:
  • Complete blood count
  • Basic biochemistry including LDH and β2-microglobulin
  • CT scan of chest, abdomen and pelvis
  • Bone marrow aspirate and biopsy 1

Treatment Algorithm for Localized Gastric MALT Lymphoma

Step 1: H. pylori Eradication (First-line for all patients)

• Standard regimen: PPI plus clarithromycin-based triple therapy with either amoxicillin or metronidazole for 10-14 days 1
• Verify eradication: Urea breath test at least 6 weeks after therapy and 2 weeks after PPI withdrawal 1
• If first attempt fails: Use alternative triple- or quadruple-therapy regimens 1

Step 2: Response Assessment

• Timing: Repeat endoscopy with biopsies 2-3 months after H. pylori eradication 1
• For H. pylori-positive patients with complete response:
  • Continue endoscopic surveillance every 6 months for 2 years, then every 12-18 months 1
  • Note: Molecular studies often show persistence of monoclonal B-cells despite histological regression - watchful waiting is appropriate 1, 2

Step 3: Management of Non-responders

• For H. pylori-positive non-responders:

  • Wait up to 12 months for response if patient has clinical and endoscopic remission but persistent histological disease 1
  • If no response after 12 months or disease progression, proceed to radiotherapy

• For H. pylori-negative patients:

  • Consider a trial of antibiotics anyway (may benefit up to 29% of patients) 3, 4
  • If no response at 2-3 months, proceed to radiotherapy 1

Step 4: Radiotherapy for Non-responders

• Dose: Moderate-dose involved-field radiotherapy (24-30 Gy) to stomach and perigastric nodes given over 3-4 weeks 1
• Excellent disease control has been reported with radiation therapy alone for stage I-II disease 1

Step 5: Systemic Therapy Options (if radiotherapy contraindicated)

• Immunotherapy: Rituximab (anti-CD20 monoclonal antibody) 1
• Chemotherapy options:
  • Oral alkylating agents (chlorambucil or cyclophosphamide)
  • Purine nucleoside analogs (fludarabine, cladribine) 1
  • Note: Patients with t(11;18) translocation are unlikely to respond to alkylating agents alone 1

Special Considerations

• Surgery is no longer recommended as initial treatment for gastric MALT lymphoma 1
• Single lesions in H. pylori-negative patients may be more likely to respond to antibiotics than multiple lesions 3
• Persistent minimal residual disease: Watchful waiting is appropriate for patients with stable residual disease after treatment, as progression is uncommon 5
• Long-term follow-up: Endoscopic surveillance with biopsies should continue for years, as relapses can occur even after complete remission 2

Treatment of Advanced Disease (Stage IV)

• For symptomatic systemic disease, rituximab plus chemotherapy is recommended 1
• Asymptomatic patients with advanced disease may be observed with periodic endoscopy and imaging 1

By following this algorithm, you can optimize outcomes for patients with localized gastric MALT lymphoma while minimizing unnecessary treatments. The high rate of response to H. pylori eradication therapy (even in some H. pylori-negative cases) makes this the clear first choice for treatment.