B2M and diffuse large B-cell lymphoma: A retrospective registry data analysis of 833 patients with de novo DLBCL treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) was conducted to establish the prognostic significance of serum beta-2 microglobulin at a ≥2.5 mg/L cutoff.