Please explain stomach lymphoma (MALT type). What is the usual prognosis and treatment?

R.S.

Lymphoma is a tumor caused by cancerous white blood cells (lymphocytes) and often is found in lymph nodes or other organs. There are several types of lymphoma, which are categorized by the appearance of the cells under the microscope. The various types tend to behave differently, with some growing rather slowly and others progressing very rapidly.

MALT lymphoma is a very specific type of lymphoma most commonly found in the stomach. MALT stands for mucosa-associated lymphoid tissue. The significance of MALT is that lymphoid tissue is normally found in certain parts of the gastrointestinal tract (such as the last part of the small intestine), but is not usually found in the stomach. Most MALT lymphoma tumors in the stomach tend to grow slowly.

A link to a type of bacterium called Helicobacter pylori (H. pylori) has been found in more than 90 percent of patients with MALT lymphoma. This has prompted researchers to speculate that H. pylori is involved in causing MALT lymphoma. In fact, several reports have been published in which patients' MALT lymphoma regressed after they took antibiotics to wipe out the H. pylori infection.

Procedures used to diagnose MALT lymphoma of the stomach are similar in many ways to those used to detect other types of lymphoma. The patient undergoes a full workup to stage the disease, including endoscopy with biopsy, CT scan of the abdomen and chest, and other blood tests. In MALT lymphoma, an important test is endoscopic ultrasound (EUS). In this test, an ultrasound probe is placed at the tip of the endoscope and used to scan close to the tumor. This provides a good view of the size and depth of the tumor -- an important factor in determining the treatment strategy. For early-stage MALT lymphoma, in which the disease hasn't advanced beyond the surface of the stomach lining, a regimen of antibiotics to treat H. pylori infection is often adequate therapy. For more advanced tumors, chemotherapy or surgery may be needed. The outlook for patients with early-stage tumors is very favorable, with cure rates of 80-90 percent. However, since a cure may take a long time to achieve, these patients may require close long-term follow-up, including several endoscopic examinations.