Depth of infiltration of primary gastric B-cell lymphomas--correlations with proliferation, apoptosis and expression of p53 and bcl-2.

Local extension has been shown to be a major prognostic factor in primary gastric B-cell lymphoma. In order to evaluate whether this parameter might be correlated with cell proliferation or its regulation, a retrospective study was performed. Fifty-three surgical specimens with primary gastric B-cell lymphomas were analysed concerning histological grading, depth of infiltration and Ann-Arbor stage. In addition, immunohistochemistry (p53[Do7], bcl-2[bcl-2-124], Ki-67 [MiB1]) and in situ end-labeling (apoptotic bodies) were applied. The depth of infiltration was significantly correlated with Ann-Arbor stage (p < 0.001) and histological grading (p < 0.002). Furthermore, the semiquantitatively evaluated expressions of Ki-67, apoptotic bodies and p53 revealed that tumours limited to the mucosa and submucosa had lower numbers of stained cells than lymphomas infiltrating the muscularis propria or beyond (p < 0.001 in all cases). Analysis of bcl-2 expression showed an inverse picture (p < 0.05). The importance of local spread of gastric lymphomas is underscored by our findings: in gastric lymphomas infiltrating the muscularis propria or beyond, powerful proliferative stimuli have been acquired, e.g. associated with p53 mutations, that are independent of the known mucosa-associated stimuli, Helicobacter pylori and auto-immunity.