High Ki67 index and bulky disease remain significant adverse prognostic factors in patients with diffuse large B cell lymphoma before and after the introduction of rituximab.

The aim of this study was to evaluate the impact of clinical variables and biologic features on response rate (RR), overall survival (OS) and progression-free survival (PFS) in 111 patients with de novo diffuse large B cell lymphoma (DLBCL). Fifty-three patients were treated with CHOP (cyclophosphamide, doxorubicin, vincristine and prednisolone) and 58 patients were treated with R-CHOP (rituximab + CHOP). The variables predictive of RR in the CHOP group were B symptoms, age, clinical stage, bone marrow involvement, bulky disease, International Prognostic Index (IPI) and Bcl-2; in the R-CHOP group, these variables were bulky disease, bone marrow involvement, IPI and Ki67 expression >80%. Multivariate analysis showed that in patients treated with CHOP, the independent prognostic factors associated with PFS were age, bulky disease, IPI and Bcl-2 and those associated with OS were performance status, clinical stage, IPI and bone marrow involvement. In contrast, in patients treated with R-CHOP, the variable shown by multivariate analysis to be an independent prognostic factor associated with PFS was bulky disease, whereas Ki67 expression >80% was associated with OS and PFS. Our data show that a high Ki67 expression and bulky disease could represent possible predictive factors of poor prognosis, which would help to identify a high-risk subgroup of newly diagnosed DLBCL.