MALT Lymphoma not Originating in the Stomach
December 1, 1997
MALT Lymphoma not Originating in the Stomach
ABSTRACT & COMMENTARY
Synopsis: MALT lymphoma most commonly occurs in the stomach as a consequence of chronic Helicobacter pylori infection. However, it can also occur in other extranodal sites such as the lung, conjunctivae, salivary glands, breast, and thyroid gland. Such presentations are rare, tend to occur in older persons, and are often localized. Radiation therapy or chemotherapy is associated with very high rates of disease-free survival.
Source: Zinzani PL, et al. Ann Oncol 1997;8:883-886.
The term malt refers to mucosa-associated lymphatic tissue. MALT lymphomas don’t necessarily occur in tissues that are lined by a mucosal epithelium, but the lymphoid masses that occur in MALT lymphoma structurally recapitulate Peyer’s patchesthus the name. Isaacson and Wright1 first described a lymphoma of mucosa-associated lymphoid tissue about 14 years ago, and, subsequently, Isaacson’s group made the remarkable discovery that MALT lymphoma of the stomach was driven by the chronic infection of the stomach with Helicobacter pylori.2 It seems highly likely that all MALT lymphomas are antigen-driven and are possibly reversible processes; however, we lack sufficient information on what antigen is driving this lymphoid proliferation in most of the tissues in which they occur.
Zinzani and colleagues collected 24 cases of MALT lymphoma occurring in non-gastric sites over the period from January 1990 to October 1995; all patients had stage IE disease. The median age was 52 years. Sites of involvement included lung (7 patients), conjunctiva (4), lacrymal gland and orbit (4), salivary gland (3), skin (3), breast (2), and thyroid gland (1). Treatments were variable and included local radiation therapy, topical interferon-alpha, and systemic combination chemotherapy (CVP or CHOP). All 24 patients achieved an initial complete response. Five relapsed, three locally and two at previously uninvolved sites. Two of the relapsed patients were reinduced into complete response, one with CVP chemotherapy and one with radiation therapy. Two are alive with disease after having achieved a partial response to salvage therapy, and one is undergoing salvage chemotherapy. All 24 patients are alive.
COMMENTARY
MALT lymphoma is considered a marginal zone lymphoma, and it accounts for about 8% of all non-Hodgkin’s lymphomas world-wide. As we have previously discussed, most MALT lymphomas occur in the stomach, but a variety of other sites may also be involved. The disease usually presents as localized extranodal disease. The optimal treatment approach has not been defined. This series of non-gastric MALT lymphoma patients has done very well whether the treatment was administered locally or systemically. Relapse-free survival was 79% at five years. In addition to the activity of primary therapy, salvage therapy also has a chance to induce long lasting remissions. But how does one decide what therapy to deliver to a particular patient? In general, localized therapy is appropriate for the sites that can be safely given radiation therapy, such as the breast and the thyroid gland. Chemotherapy is favored in patients with lung or liver primary lesions. Lesions affecting the eyes (conjunctiva), lacrymal glands, or orbit can be treated with either radiation therapy or with topical interferon. Relapsed disease should be treated aggressively with systemic therapy, if necessary.
References
1. Isaacson PG, Wright DH. Cancer 1983;52:1410-1416.
2. Wotherspoon AC, et al. Lancet 1993;342:575-577.
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