The Impact of Relative Dose Intensity (RDI) of CHOP on Outcome of Diffuse Large B-Cell Lymphoma: Results of a Single Center Study.

Introduction: The achievement of a clinical response to the first induction chemotherapy has been considered for predicting survival in patients (pts) with aggressive non-Hodgkin lymphoma (NHL). Reduced dose intensity of chemotherapy has been likely to compromise long-term outcome of the patients with aggressive NHL treated with a standard chemotherapy of cyclophosphamide (CY), doxorubicin (ADR), vincristine and prednisone (CHOP). In particular, recent studies have revealed the relevance of relative dose intensity (RDI) to clinical outcomes, with reduced RDI leading to a poor survival, as well as the impact of RDI<85% for aggressive NHL with detailed analysis of risk factors influencing reduce RDI<85% (

Methods: Data were retrospectively collected on 100 pts with DLCL who had been initially treated with more than 3 courses of CHOP (n=70) or CHOP plus rituximab (CHOP-R, n=30) at our institution between 1995 and 2006. We evaluated whether RDI might affect clinical outcomes, including complete response (CR) and event free survival (EFS). The average RDI derived from CY and ADR (referred to as RDI-CY/ADR) was determined for each patient, with classified into 2 populations according to the differences from the value of 85%, including RDI-CY/ADR<85% (n=60), and RDI-CY/ADR≥85% (n=40).

Results: The median age of the study population was 54 years (range, 17 to 76), with 36 pts older than 60 years (yrs) of age. According to International Prognostic Index (IPI) score, pts were classified into 2 groups of low/ low-intermediate (n=46) and high/ high-intermediate (n=54). The overall CR rate reached 62%, and the probability of overall survival (OS) or EFS at 5 years estimated 77% or 43%, respectively with a median follow-up of 13.3 months. Multivariate analysis identified RDI-CY/ADR<85%, as well as IPI score to be associated with CR rate and EFS. Thus, RDI-CY/ADR<85% and IPI score of high/ high-intermediate were significant factors for lower CR rate (as RDI-CY/ADR≥85%, HR=0.3, 95% CI 0.1 to 0.7, p=0.009, and HR=5.5, 95% CI 2.2 to 14, p<0.001, respectively), and for reduced EFS (HR=1.9, 95% CI 1.0 to 3.7, p=0.048, and as IPI score of low/ low-intermediate HR=0.3, 95% CI 0.2 to 0.6, p<0.001, respectively). Furthermore, logrank analysis revealed that CY/ADR-RDI<85% was the significant factor for reduced EFS in non elderly pts (≤60 yrs of age), or in pts with IPI score of low/ low-intermediate (p=0.01, p=0.02, respectively).

Conclusion: These data thus suggested the impact of RDI-CY/ADR<85% in influencing outcomes of the pts with DLCL, in terms of CR rate and EFS. Further investigation is currently planned to confirm this promising results with longer follow-up in larger numbers of pts with NHL.