Microsatellite Instability in Gastric B-cell Lymphoma

Lee, Hyuk; Kim, Jae J; Kim, Jeong Hwan; Lee, Jun Haeng; Son, Hee Jung; Rhee, Poong Lyul; Rhee, Jong Chul; Ko, Young Hyeh

Abstract

BACKGROUND/AIMS: Microsatellite instability (MSI) reflects the defect in DNA mismatch repair (MMR) pathways and plays an important role in certain malignancies. However, the role of MSI in the development of gastric B-cell lymphomas remains unsettled. We aimed to investigate the clinical significance of MSI in patients with gastric B-cell lymphoma. METHODS: Seven micosatellite loci (BAT25, BAT26, D2S123, D5S346, D17S250, D14S50, IGF-IIR) were used for MSI analyses. Microsatellite genotypes were categorized as microsatellite stable (MSS, no positive marker), low frequency MSI (MSI-L, <40% positive marker) and high frequency MSI (MSI-H, >40% positive marker). Among the gastric B-cell lymphoma patients who underwent MSI analysis between September 2002 and May 2003, twenty-two patients were enrolled. Median follow-up duration was 23 months (6-32 months). RESULTS: Median age was 46 years (26-73 years). Male to female ratio was 1:1.4. Twelve patients (54.5%) underwent Helicobacter pylori (H. pylori) eradication and ten patients (45.5%) underwent chemoradiation therapy. No case presented MSI-H. MSI-L was observed in 40.9% (9/22). Between MSS group and MSI-L group, there was no significant difference in age, tumor stage, location, grade of large cell component, H. pylori infection, bulk of tumor and proportion of regression or recurrence. All positive markers belonged to the dinucleotide markers. CONCLUSIONS: The current study suggests that the role of MSI is questionable in the development of gastric B-cell lymphoma due to their low incidence.