Background: Low-grade gastric MALT lymphoma is an uncommon tumour for which a close association with chronic Helicobacter pylori infection has been suggested. However, given the rarity of MALT lymphoma of the stomach despite the high prevalence of H. pylori infection, it seems plausible that genetic host factors might play a fundamental role in gastric lymphomagenesis.
Patients and methods: We retrospectively reviewed the medical records of 83 patients with low-grade gastric MALT, all of whom resided in a geographic area (southern Switzerland and northern Italy) where the incidence of gastric tumours appears to be uncommonly high.
Results: One or more additional cancers were observed in 17 of 83 patients (20%, 95% CI 12% to 31%) for a total of 23 tumours. Of these, 5 were diagnosed prior to, 12 concomitantly with, and 7 after the gastric MALT lymphoma. Eleven patients had a single additional solid tumour (13%, 95% CI 7% to 22%); 3 patients had non-Hodgkin's lymphoma and one had Hodgkin's disease. Multiple additional cancers were present in 3 cases. Nine of 83 patients have died and 8 of them of a second cancer.
Conclusions: Unexpectedly an extraordinarily large number of patients with other malignancies was observed in this series. The reasons for this finding are still unknown, but genetic alterations are speculated to play an important role.