The normal human stomach is devoid of any organized lymphatic tissue. Acquisition of mucosa-associated lymphatoid tissue (MALT) in the stomach is considered to be a direct consequence of chronic infection with Helicobacter pylori. Thus, MALT appears to be part of the host defense against the pathogen H. pylori. Consequently, lymphomas arising from gastric MALT may be seen as an end point of a clonal evolution starting from the infection. Cumulative data from several studies show that eradication of H. pylori induces complete histologic remissions in about 70%-80% of the patients. Here we present data of an extended analysis of an ongoing multicenter trial. Eighty-four patients with low-grade gastric MALT lymphoma in stage EI were treated using a dual regimen to eradicate H. pylori. Complete remission was observed in 68 (81%) patients; a partial remission was found in seven (8%) patients. In contrast, nine (11%) patients revealed "no change" and were referred for alternative treatment strategies. The majority of these cases were found to harbor high-grade lymphomas in deeper mucosal areas. Polymerase chain reaction (PCR) performed on the VDJ rearrangements of the immunoglobulin heavy chain yielded monoclonal bands in 50 of 65 analyzed patients (77%) at diagnosis. Interestingly, in patients analyzed during follow up after achieving complete histologic remission, ongoing PCR monoclonality was found in 19 of 39 eligible patients (49%). Several patients who developed local relapse of the lymphoma were found in the group with ongoing PCR monoclonality. Together with data from the literature, these results suggest that the majority of low-grade gastric MALT lymphomas in stage EI respond to eradication of H. pylori. Longer follow-up investigations are necessary to determine whether remissions really indicate a cure from the disease and to elucidate whether PCR monoclonality after complete histological remission is predictive of increased relapse rate.
