A Marginal zone lymphomas (MZL) involve immune cells known as B cells, and account for between 5% and 17% of all non-Hodgkin lymphomas.[i] The three main subtypes of MZL are extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma), nodal MZL, and splenic MZL. Of these, MALT lymphoma is the most common.
MZL primarily affects adults, and roughly half of people with MZL are over the age of 60 at the time of diagnosis. The symptoms that may be caused by MZL depend on the type and location of the MZL. MALT lymphoma commonly involves the stomach, and patients may report abdominal pain, heartburn, and indigestion. MALT lymphoma may also develop in other areas of the body, such as the area around the eye, the salivary glands, or the lungs.[ii] Splenic MZL may be detected because of enlargement of the spleen or abnormal blood cell counts.[iii] These types of lymphoma tend to be indolent (slow growing).
Diagnosis and Staging
If lymphoma is suspected, patients will usually have a biopsy performed. A biopsy involves the removal and examination of a sample of affected tissue. It allows a doctor to determine the presence and type of lymphoma. A diagnostic workup may also involve a physical exam, blood tests, and imaging scans.
If the biopsy confirms a diagnosis of MZL, patients may undergo additional tests and imaging scans to determine the extent (stage) of the disease.
Treatment of MALT Lymphoma
Gastric (stomach) MALT lymphoma
Many cases of gastric (stomach) MALT lymphoma are the result of chronic infection with a bacterium known as Helicobacter pylori (H. pylori). For patients with early-stage gastric MALT lymphoma who test positive for this infection, use of antibiotics to eliminate the infection often provides effective lymphoma treatment.[iv] To evaluate treatment response, your doctor will likely perform an endoscopy (a procedure that involves the use of a scope to view the inside of your stomach) a few months after treatment. Antibiotic treatment may be less effective for lymphomas that contain certain genetic changes, and your doctor may test for these genetic changes prior to starting treatment.
For early-stage gastric MALT lymphomas that test negative for H. Pylori (or that do not respond to treatment with antibiotics), treatment often involves radiation therapy. Chemotherapy and/or Rituxan® (rituximab) are also options for some patients. Rituxan is a type of drug known as a monoclonal antibody. It recognizes and binds to a protein (CD20) found on the surface of B cells, including the cancerous B cells of MZL. The binding of Rituxan to the B cell prompts the immune system to destroy the cell, and may also have direct anticancer effects on the cell.
Advanced-stage gastric MALT lymphoma is less common. Depending on whether or not the condition is causing symptoms, treatment may involve observation, use of chemotherapy and/or Rituxan, or participation in a clinical trial. Clinical trials are studies that evaluate the effectiveness and safety of new cancer drugs or cancer treatment strategies. Good sources of information about ongoing clinical trials include the patient’s cancer treatment team and the website of the National Cancer Institute.
Non-gastric MALT lymphoma
Although the stomach is the most common location of MALT lymphoma, the condition can also involve many other parts of the body. Treatment of early-stage MALT lymphoma in these other sites may involve radiation therapy, surgery, or observation. Some cases may be candidates for chemotherapy and/or immunotherapy (with a drug such as Rituxan) or participation in a clinical trial.
Splenic MZL that is not causing symptoms can often be managed with observation, and patients may experience stable disease without treatment for many years.
Some cases of splenic MZL are linked with hepatitis C virus (HCV) infections, and treatment of HCV can provide a benefit. Other treatments that may be used for splenic MZL include splenectomy (surgical removal of the spleen) or Rituxan.
Nodal MZL is a rare condition. The Guidelines panel of the National Comprehensive Cancer Network recommends that nodal MZL be treated according to the guidelines for follicular lymphoma (another indolent type of NHL).[v] Treatment may involve radiation therapy, chemotherapy, immunotherapy (with a drug such as Rituxan), observation, or participation in a clinical trial.
Strategies to Improve Treatment
In an effort to further improve treatment outcomes for patients with MZL, researchers continue to develop and test new drugs and other approaches to treatment. Zevalin® (ibritumomab tiuxetan), for example, is a radioimmunotherapeutic. Radioimmunotherapy involves treatment with a radioactive substance linked to a monoclonal antibody. In the case of Zevalin, the antibody recognizes and binds to the CD20 protein found on the surface of B cells. The binding of the antibody delivers the radiation directly to the cancer. Zevalin has been approved for the treatment of patients with certain other types of non-Hodgkin lymphoma, and it is also producing promising results in studies of patients with MZL.[vi]
Patients who are interested in participating in a clinical trial of new treatment approaches may wish to discuss the risks and benefits with their physician. Information about ongoing clinical trials is also available from the National Cancer Institute.
[i] Thieblemont C. Clinical presentation and management of marginal zone lymphomas. Hematology Am Soc Hematol Educ Program. 2005:307-13.
[ii] Troch M, Kiesewetter B, Raderer M. Recent developments in nongastric mucosa-associated lymphoid tissue lymphoma. Curr Hematol Malig Rep. 2011; 6:216-221.
[iii] Thieblemont C, Davi F, Noguera M-E, Briere J. Non-MALT marginal zone lymphoma. Curr Opin Hematol. 2011;18:273-279.
[iv] Stathis A, Bertoni F, Zucca E. Treatment of gastric marginal zone lymphoma of MALT type. Expert Opin Pharmacother. 2010; 11:2141-2152.
[v] NCCN Clinical Practice Guidelines in Oncology. Non-Hodgkin’s Lymphomas. Version 1.2013.
[vi] Esmaeli B, McLaughlin P, Pro B et al. Prospective trial of targeted radioimmunotherapy with Y-90 ibritumomab tiuxetan (Zevalin) for front-line treatment of early-stage extranodal indolent ocular adnexal lymphoma. Ann Oncol. 2009;20:709-14.