Prognostic impact of β₂-microglobulin in patients with non-gastric mucosa-associated lymphoid tissue lymphoma.

Although serum β₂-microglobulin (B2M) has been suggested as a prognostic factor for several hematologic malignancies, it has not been comprehensively investigated in non-gastric mucosa-associated lymphoid tissue (MALT) lymphoma. Between January 2000 and May 2013, a total of 174 patients with non-gastric MALT lymphoma were identified from a prospectively developed database. Baseline serum B2M was elevated in 17 (10%) patients. In univariate analysis, serum B2M ≥ 2.5 mg/L was significantly associated with progression-free survival (PFS, p < 0.001) and overall survival (OS, p < 0.001). Multivariate analysis identified serum B2M as an independent prognostic factor in PFS (hazard ratio [HR] = 3.5, 95% confidence interval [CI]: 1.2-10.0; p = 0.02) and OS (HR = 26.9, 95% CI: 2.7-269.7; p = 0.005), after adjustment for IPI and treatment modalities. Baseline serum B2M is an independent prognostic factor in patients with non-gastric MALT lymphoma.