Background: Non-Hodgkin's lymphoma (NHL) originating in mucosa-associated lymphoid tissue (MALT) is supposed to have different clinical behavior from lymph node NHL. To test this hypothesis, the authors compared data of gastric NHL patients with lymph node NHL patients in a population-based registry for differences in clinical presentation and prognosis.
Methods: Data from 1981-1989 on patients with primary gastric NHL (n = 109) and patients with primary lymph node NHL (n = 658) were retrieved from a Dutch population-based NHL registry. Patients were compared for stage distribution, involved sites, and survival. The prognostic value of grading lymphomas according to the malignancy grades of the Working Formulation for Clinical Usage was compared with the value of grading MALT NHLs as either low grade or high grade malignancies.
Results: Patients with gastric NHL presented more often with localized disease. Stage IV patients had a higher rate of dissemination to other non-lymph node sites but less frequent localization in the bone marrow. The restricted pattern of dissemination was reflected in a significantly lower recurrence rate for gastric NHL. Gastric NHL patients had significantly better disease free survival than lymph node NHL patients (80% and 44% at 5 years, respectively; P < 0.001). In contrast, overall survival did not significantly differ between the two groups, and it appeared to depend on disease stage. Grading MALT lymphoma as either low grade (26%) or high grade (70%) malignancies did not provide better prognostic information than grading according to the Working Formulation for Clinical Usage (low 8%, intermediate 75%, high 9%).
Conclusions: Primary gastric NHL shows a restricted dissemination pattern, which gives support to the MALT lymphoma concept. Although this might explain the superior disease free survival observed for gastric NHL patients, it does not translate into better overall survival for these patients.