Prognostic relevance of serum β2 microglobulin in patients with follicular lymphoma treated with anthracycline-containing regimens. A GISL study

Background and Objectives Although serum beta 2 microglobulin (beta 2M) is an easy parameter to measure, and overexpressed in a large number of lymphoproliferative diseases, its prognostic value has been largely underestimated. The present study examined the influence of beta 2M levels on overall survival (OS) of patients with follicular lymphoma (FL). Design and Methods The prognostic role of beta 2M was evaluated in 236 patients with FL identified from the databases of the Gruppo ltaliano per lo Studio dei Linfomi (GISL) and treated with anthracycline-based regimens from 1993 to 2003. Results Elevated serum beta 2M levels were found in 82 patients (35%). According to multivariate logistic regression analysis, elevated beta 2M levels were associated with elevated lactate dehydrogenase (LDH) (p=0.021), age (p=0.029), and number of involved nodal areas (p<0.001). The percentage of elevated beta 2M levels increased progressively with increasing FLIPI scores (17%, 38%, and 63% in the low-, intermediate-, and high-risk groups, respectively). Five-year OS was 61% (95% CI, 47-73%) and 89% (95% CI, 82-93%) for patients with elevated vs normal 132M levels respectively (p<0.001). Cox regression analysis showed that beta 2M level had an independent and stable prognostic value (HR=3.0; 95%CI, 1.6-5.7). In a multivariate analysis the impact of beta 2M level on survival was independent of FLIPI score, with a HR of 2.94 (95% CI, 1.54-5.62). Interpretation and Conclusions Our results demonstrate that in patients treated in the pre-rituximab era, beta 2M level was an independent prognostic marker in addition to FLIPI score. We thus suggest that beta 2M be routinely assessed and tested in future prognostic studies of FL patients treated with combination chemotherapy and anti-CD20 agents.