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About MALT Lymphoma

Mucosa-associated lymphoid tissue (MALT) lymphoma is a type of slow-growing non-Hodgkin’s lymphoma (NHL). NHL includes several different types of cancers that originate within the immune system. MALT lymphoma tends to develop outside of the lymph nodes, most commonly in the stomach, salivary glands, lungs, or thyroid.

Infection with the bacterium Helicobacter pylori (H. pylori) is associated with the development of MALT lymphoma and eradication of  H. pylori can result in a complete disappearance of lymphoma in many patients with early-stage MALT lymphoma of the stomach.

Treatment of Gastric MALT Lymphoma

Researchers from Japan initially demonstrated that infection with a bacterium known as Helicobacter pylori was present in 72% of patients with MALT lymphoma of the stomach. Antibiotic therapy effectively treated MALT lymphoma of the stomach in a majority of patients and individuals who were negative for Helicobacter pylori or resistant to antibiotics could be effectively treated with radiation therapy.They observed the following:

  • Helicobacter pylori was identified in 41 of the 57 patients (72%). The researchers did not find clinical differences between patients with and without Helicobacter pylori infection.
  • Among patients with Helicobacter pylori infection, 74% responded to treatment with antibiotics.
  • Among patients without Helicobacter pylori infection, one out of nine (11%) responded to treatment with antibiotics.
  • Radiation therapy was administered to 14 patients with antibiotic-resistant or Helicobacter pylori-negative MALT lymphoma. Local control of lymphoma was achieved in 93% of these patients, but three had a distant recurrence of lymphoma.
  • Two patients with Helicobacter pylori-negative MALT lymphoma of the stomach died of diffuse large B-cell lymphoma.

The researchers concluded that radiation therapy was effective local therapy for Helicobacter pylori-negative or antibiotic-resistant MALT lymphoma of the stomach, but that some patients have distant recurrences and progression to aggressive lymphoma.

In order to further assess the role of antibiotics in the treatment of patients with early-stage MALT lymphoma of the stomach, researchers in Taiwan evaluated two groups of patients. One group had low-grade MALT lymphoma, while the other had high-grade transformed tumors. The patients with high-grade lymphoma had diffuse large B-cell lymphoma (DLBCL) with features of MALT. Some have speculated that DLBCL(MALT) lymphoma is not dependent on Helicobacter pylori and will not be affected by antibiotic treatment of Helicobacter pylori.2

A large majority of both groups of patients were infected with Helicobacter pylori -94% of the patients with low-grade lymphoma and 100% of the patients with high-grade lymphoma. Patients were treated with two weeks of antibiotics. The antibiotics were highly effective:

  • Antibiotics eliminated the Helicobacter pylori infection in 97% of the low-grade patients.
  • Helicobacter pylori infection was eliminated in 92% of the high-grade patients.

Among those whose infection was eliminated:

  • 80% of patients with low-grade lymphoma experienced a complete disappearance of detectable lymphoma.
  • 64% of patients with high-grade lymphoma had a complete disappearance of their disease.

None of the patients who were initially negative for Helicobacter pylori and none who had persistent infection after antibiotic treatment experienced a complete disappearance of lymphoma. After roughly five years of follow-up, lymphoma recurred in three (13%) of the patients with low-grade lymphoma; none of the patients with high-grade lymphoma had a recurrence.

The researchers conclude that antibiotic treatment of Helicobacter pylori infection is effective for both low-grade MALT lymphoma of the stomach as well as DLBCL(MALT). They recommend additional studies to confirm that antibiotics are an appropriate first-line treatment for early stage, Helicobacter pylori-positive DLBCL(MALT).

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Failure to Achieve Complete Remission

Patients with MALT lymphoma who do not respond or stop responding to antibiotics can be treated with surgery, radiation therapy, and/or chemotherapy.

Researchers from Harvard have reviewed the outcomes of patients treated with early-stage MALT lymphoma in 66 patients whose cancer progressed despite antibiotic therapy. Patients were treated with the following therapies: 68% were treated with radiation therapy, 22% were treated with surgery followed by radiation therapy, 3% were treated with surgery and chemotherapy, and one patient received chemotherapy.

  • At five years progression-free survival was 76%.
  • At five years overall survival was 91%.
  • Patients who received radiation therapy had improved progression-free survival and overall survival compared with patients who had not received radiation therapy.

The researchers concluded that radiation therapy appears to provide an improvement in survival among patients with early-stage MALT lymphoma who have not responded to or have stopped responding to antibiotic therapy.4

The effectiveness of radiation therapy has been confirmed by other researchers and longer term follow up suggests treatment-related toxicities are rare. Overall 1% of patients treated with radiation developed esophageal stricture that required dilation and 1.6% developing a secondary malignancy within the radiation field. Heartburn was the most common side effect, which is effectively treated with proton pump inhibitors.5

Among patients who have minimal residual MALT lymphoma of the stomach after eradication of H. pylori infection, outcomes appear to be good even without additional cancer treatment. 

To explore whether these additional treatments are necessary among patients with Stage I MALT lymphoma of the stomach and minimal residual disease after H. pylori treatment, researchers conducted a study among 108 patients. Twelve months after eradication of H. pylori, these patients still had evidence of minimal residual MALT lymphoma. Instead of receiving additional cancer therapy, the patients received regular endoscopies and multiple biopsies.

Study participants were followed for a median of 42 months.

  • 32% of patients eventually went into complete remission.
  • 62% of patients remained stable (there was no evidence of change in the residual MALT lymphoma).
  • 5% of patients experienced lymphoma progression, and one of the patients developed a high-grade lymphoma.

The researchers concluded that most of the patients in this study (Stage I patients who had minimal residual gastric MALT lymphoma following complete eradication of H. pylori infection) had good outcomes without additional cancer treatment. The researchers note: “A watch and wait strategy with regular endoscopies and biopsies appears to be safe and may become the treatment of choice in this situation. Longer follow up is needed to establish this definitively.”


  1. Akamatsu T, Mochizuki T, Okiyama Y et al. Comparison of Localized Gastric Mucosa-Associated Lymphoid Tissue (MALT) Lymphoma With and Without Helicobacter pylori Infection. Helicobacter. 2006; 11:86-95.
  2. Chen L-T, Lin J-T, Tai JJ et al. Long-term results of anti-Helicobacter pyloritherapy in early-stage gastric high-grade transformed MALT lymphoma. Journal of the National Cancer Institute. 2005;97:1345-1353.
  3. Fischbach W, Goebeler ME, Ruskone-Fourmestraux A et al. Most patients with minimal histological residuals of gastric MALT lymphoma after successful eradication of Helicobacter pylori can be managed safely by a watch and wait strategy: experience from a large international series. Gut. 2007;56:1685-1687.
  4. Tsai HK, Li S, Ng AK, et al. Role of radiation therapy in the treatment of stage I/II mucosa-associated lymphoid tissue lymphoma. Annals of Oncology [published online]. January 11, 2007.
  5. Yahalom J, Xu AJ, Noy A, et al. Involved-site radiotherapy for Helicobacter pylori–independent gastric MALT lymphoma: 26 years of experience with 178 patients. Blood Adv. 2021;5(7):1830-1836. doi:10.1182/bloodadvances.2020003992