Serum interleukin-18 level is associated with the outcome of patients with diffuse large B-cell lymphoma treated with CHOP or R-CHOP regimens

Background: We have previously reported that serum interleukin‐18 (IL‐18) concentration predicted the clinical outcome of patients with aggressive non‐Hodgkin’s lymphoma treated with cyclophosphamide, doxorubicin, vincristine, and prednisolone (CHOP). When rituximab (R) was added to this regimen, the prognosis of diffuse large B‐cell lymphoma (DLBCL) was markedly improved. Patients and Methods: In this study, we re‐evaluated the prognostic significance of serum IL‐18 in 227 DLBCL patients. Seventy‐three patients received CHOP before R‐era, and 154 patients received rituximab‐cyclophosphamide, doxorubicin, vincristine, and prednisolone (R‐CHOP) recently. Result: Four‐year overall survival (4‐yr OS) rates for patients in CHOP group with IL‐18 ≥ 720 pg/mL and <720 pg/mL were 8.2% and 67.3% (P < 0.0001), respectively, and 4‐yr OS rates with IL‐18 ≥ 590 and <590 pg/mL in R‐CHOP group were 53.4% and 77.8% (P = 0.0008), respectively. Multivariate analysis revealed that serum IL‐18 correlated most significantly with OS and progression‐free survival (PFS) in both groups (OS: P < 0.0001, PFS: P < 0.0001, in CHOP group; OS: P = 0.0147, PFS: P = 0.0084 in R‐CHOP group). The high serum IL‐18 patients with poor prognostic group in revised IPI or with non‐germinal center B‐cell phenotype had a very poor prognosis. Conclusion: Serum IL‐18 might be a powerful prognostic factor for DLBCL in R‐era.