Prognostic Impact Of Beta-2 Microglobulin In Patients With Non-Gastric Marginal Zone Lymphoma

Although serum Beta-2 microglobulin (B2M) has been suggested as a prognostic factor for several hematologic malignancies, this was rarely investigated in marginal zone lymphoma (MZL).

Between January, 2000, and May, 2013, a total of 270 patients with non-gastric (NG)-MZL were identified from database of Asan Medical Center, Seoul, Korea. Among them, pretreatment baseline serum B2M was available in 204 patients. Progression-free survival (PFS) and overall survival (OS) were compared according to the level of B2M with cut-off value of 2.5 mg/L.

Median age of study population was 51 year-old (range, 16-81) and 85 (42%) patients were male. Thirty (15%) patients had nodal MZL and 174 (85%) had extranodal MALToma. B2M ≥2.5 mg/L was related with more adverse clinical features, such as poor performance status, ≥2 extranodal sites, advanced stage (III-IV), anemia, elevated LDH, bone marrow invasion, and higher IPI risk group. In univariate analysis, serum B2M (<2.5 mg/L vs ≥2.5 mg/L) was significantly associated with PFS (p<0.001) and OS (p<0.001). In multivariate analysis including B2M and International Prognostic Index (IPI), serum B2M ≥2.5 mg/L was an independent adverse prognostic factor in terms of PFS (hazard ratio [HR]=3.7, 95% CI, 1.5-9.1; p=0.005) and OS (HR=7.5, 95% CI, 1.7-32.7; p=0.008). In analysis including Korean MZL Prognostic Index (MZLPI: nodal MZL, ECOG performance status ≥2 and advanced stage), B2MG ≥2.5 mg/L was also significant for PFS (HR=3.5, 95% CI, 1.5-7.7; p=0.003) and OS (HR=7.3, 95% CI 1.9-28.2; p=0.004).

In patients with NG-MZL, baseline serum B2M is a powerful prognostic factor for PFS and OS, independent of validated prognostic indexes, such as IPI and MZLPI.

No relevant conflicts of interest to declare.