Prognostic value of pretreatment serum beta-2 microglobulin level in advanced classical Hodgkin lymphoma treated in the modern era

The prognostic value of pretreatment serum beta-2 microglobulin (B2MG) level in advanced Hodgkin lymphoma (HL) patients treated in the modern era has not been well established. We conducted a retrospective study involving 202 advanced classical HL (cHL) patients treated from 1998.5 to 2015.7 to evaluate the impact of serum B2MG level on prognosis. Multivariate analysis showed that serum B2MG level ≥ 2.5 mg/L was an independent predictor for freedom from progression (FFP) (P = 0.001), lymphoma-specific survival (P = 0.030) and overall survival (P = 0.034). The 5-year FFP of patients with serum B2MG level ≥ 2.5 mg/L was 66.8%, compared with 89.7% in patients with B2MG level < 2.5 mg/L (P < 0.001). The traditionally used International Prognostic Score (IPS) remained prognostic for FFP (P = 0.013) but the predictive range narrowed, with 5-year FFP ranging from 90.9% to 62.3%. The 5-year FFP of the 44 patients with both IPS ≥ 3 and serum B2MG ≥ 2.5 mg/L was 50.7%, which was significantly worse than that of the 87 patients with only one of the two factors (81.9%, P < 0.001) or the 71 patients with both B2MG < 2.5 mg/L and IPS < 3 (91.1%, P < 0.001). The difference of FFP between the latter two groups was smaller but also significant (P = 0.038). In summary, our data suggest pretreatment serum B2MG level ≥ 2.5 mg/L was an independent unfavorable prognostic factor in advanced cHL patients treated in the modern era. It improves IPS in predicting the outcomes as the combination of IPS and B2MG indentified a wider prognostic range than IPS alone with a sizable number of patients in different risk groups.