MALT lymphomas: pathogenesis can drive treatment.

Marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT) lymphoma is an indolent B-cell non-Hodgkin lymphoma arising from the lymphoid tissue at extranodal sites. It is genetically characterized by different, usually mutually exclusive, genetic abnormalities that lead to activation of the nuclear factor kappa B (NF-kappaB) pathway. These lymphomas can arise in any extranodal organ or tissue; however, the stomach--where MALT lymphoma development has been strongly linked to chronic Helicobacter pylori infection--is the most common site. Other microorganisms have been associated with non-gastric MALT lymphomas, but the evidence for such associations is weaker. Treatment aimed at eradicating H pylori infection results in remission of gastric MALT lymphoma in most patients and represents a model of anticancer treatment based on the eradication of the causative factor. Treatment of non-gastric MALT lymphomas is much less well established; either radiotherapy or systemic therapy (with chemotherapy and/or rituximab [Rituxan]) can be effective, while antibiotic therapies (e.g., doxycycline in ocular adnexal lymphomas) should still be considered investigational.