Serum soluble interleukin‐2 receptor level and immunophenotype are prognostic factors for patients with diffuse large B‐cell lymphoma

Diffuse large B-cell lymphoma is the most common form of non-Hodgkin lymphoma. Although many studies have attempted to identify prognostic factors, most have focused on conventionally treated patients. The influence of anti-CD20 antibody (rituximab) should be considered now. We evaluated the prognostic significance of serum soluble interleukin-2 receptor levels and germinal center B-cell-like or non-germinal center B-cell like subgroups in 80 patients with diffuse large B-cell lymphoma, who had been treated with rituximab. Serum soluble interleukin-2 receptor levels ranged from 322 to 39900 U/mL (median 1365 U/mL). Sixteen (20%) were germinal center B-cell-like subgroups, and the remainder (80%) non-germinal center B-cell-like. Survival analysis associated lower serum soluble interleukin-2 receptor level and germinal center B-cell-like phenotype with better overall survival (P = 0.015), whereas multivariate analysis, including International Prognostic Index factors, revealed that only higher performance status score and higher serum lactate dehydrogenase levels significantly affected survival. However, serum soluble interleukin-2 receptor levels were elevated in patients with higher International Prognostic Index scores as well as in the non-germinal center B-cell-like subgroup. Serum soluble interleukin-2 receptor levels, International Prognostic Index, and subphenotypes were strongly correlated with each other. Our study showed that soluble interleukin-2 receptor is quite useful and may serve as a substitute for the International Prognostic Index, especially for patients undergoing treatment. Moreover, the differentiation between the germinal center B-cell-like and non-germinal center B-cell-like phenotypes is also useful for predicting patients with diffuse large B-cell lymphoma, even among those treated with rituximab.