HLA-DR antigen and bax protein expression in patients with primary non-Hodgkin's gastric lymphoma

Primary gastric lymphoma represents a rare gastrointestinal malignancy with an unclear prognosis. The aim of this study was to determine the prognostic significance of HLA-DR antigen and bax expression in patients with primary non-Hodgkin's gastric lymphoma. We immunohistochemically studied bax protein and HLA-DR antigen expression in 36 B-cell, MALT-type primary gastric lymphoma patients diagnosed and treated in our department from 1990 to 1995. Ten non-malignant gastric tissue specimens were used as benign controls. Clinicopathological and survival data were correlated with the staining results. HLA-DR antigen expression was observed in 33 gastric lymphoma patients (91.7%). Positive bax staining was found in 24 gastric lymphomas (66.7%) and in none of the benign cases studied. In the univariate analysis, those gastric lymphoma patients who expressed HLA-DR antigen in more than 15% of their tumor cells, presented a significantly improved 5-year survival rate (75% vs. 37.5%, p = 0.04). Furthermore, gastric lymphoma patients who were bax(+)/HLA-DR(+) had a statistically better overall survival compared to those who were bax(-)/HLA-DR(-) (82.4% vs. 25%, p = 0.01). HLA-DR antigen expression was associated with a favorable clinical outcome. Its expression improved the predictive value of bax protein expression in non-Hodgkin's gastric lymphoma patients. The combined use of these markers permits the identification of a high-risk group of patients that may benefit from a more aggressive therapeutic approach.