Gastric MALT lymphoma: epidemiology and high adenocarcinoma risk in a nation-wide study.

BACKGROUND: Gastric marginal zone non-Hodgkin lymphomas MALT type (gMALT) and gastric adenocarcinomas (GC) are long-term complications of chronic Helicobacter pylori gastritis, however, the incidence of gMALT and the GC risk in these patients is unclear.

OBJECTIVE: To evaluate epidemiological time trends of gMALT in the Netherlands and to estimate GC risk.

METHODS: Patients with a first diagnosis of gMALT between 1991 and 2006 were identified in the Dutch nation-wide histopathology registry (PALGA). Age-standardised incidence rates were calculated. The incidences of GC in patients with gMALT and in the Dutch population were compared. Relative risks were calculated by a Poisson Model.

RESULTS: In total, 1419 patients were newly diagnosed with gMALT, compatible with an incidence of 0.41/100,000/year. GC was diagnosed in 34 (2.4%) patients of the cohort. Patients with gMALT had a sixfold increased risk for GC in comparison with the general population (p<0.001). This risk was 16.6 times higher in gMALT patients aged between 45 and 59 years than in the Dutch population (p<0.001).

CONCLUSIONS: GC risk in patients with gMALT is six times higher than in the Dutch population and warrants accurate re-evaluation after diagnosis and treatment for gMALT.