B2M and diffuse large B-cell lymphoma: In an independent validation cohort of 258 R-CHOP treated patients with de novo DLBCL, elevated beta-2 microglobulin levels remained a significant poor prognostic factor for PFS (HR, 2.03; 95% CI, 1.23–3.32; p = 0.005) and exhibited a strong trend of association with worse OS (HR, 1.64; 95% CI, 0.98–2.75; p = 0.062).