The prognostic significance of the number of extranodal sites in the patients with disseminated diffuse large B-cell lymphoma treated with R-CHOP

Abstract

8570 Background: The combination of rituximab and CHOP chemotherapy (R-CHOP) has improved survival of patients with diffuse large B-cell lymphoma (DLBCL). Recently, several reports have shown that standard International Prognostic Index (IPI) became less powerful prognostic predictor in patients with DLBCL in the era of R-CHOP. We evaluated the prognostic factors of DLBCL patients treated with R-CHOP. Detailed analysis was planned regarding the number of extranodal sites because of its higher frequency in Korea. Methods: Between January 2002 and May 2008, 126 patients with stage III/IV DLBCL treated with R-CHOP were identified. We performed the retrospective analysis of the clinicopathologic factors and verified the predictive power of standard IPI and revised IPI (R-IPI) which was reported by the study group of British Columbia. Various numbers of extranodal sites were analyzed for further stratification and we set E-IPI as the IPI when the number of extranodal sites is stratified in ≤2 vs >2. Results: In the univariate analysis, the number of extranodal sites (≤2 vs >2) was a significant prognostic factor for complete response (CR) (p=0.04), event-free survival (EFS) (p=0.01) and overall survival (OS) (p<0.001). Age was also significant for EFS (p=0.03). When the number of extranodal site was stratified differently (0 vs >0, or ≤1 vs >1), these were not associated with CR, EFS and OS. On the multivariate analysis, the number of extranodal sites (≤2 vs >2) remained significant for EFS (p<0.01, HR 2.6) and OS (p<0.01, HR 3.5). The standard IPI identified 3 risk groups with 2-year EFS; 68%, 55%, 56% (p=0.17) and 2-year OS; 85%, 68%, 58%, respectively (p=0.04). The R-IPI classified 2 risk groups with 2-year EFS; 65%, 50% (p=0.02) and 2-year OS 76%, 62%, respectively (p=0.04). The E-IPI represented 3 risk groups with 2-year EFS; 79%, 56%, 42% (p=0.01) and 2-year OS; 86%, 70%, 39%, respectively (p=0.001). The patient group with survival of less than 50% was only recognized by E-IPI. Conclusions: The number of extranodal sites (≤2 vs >2) is the most significant prognostic factor of EFS and OS. Although all three indices remain predictive, E-IPI is the best model to identify the prognostic group in this cohort with stage III/IV DLBCL treated with R-CHOP. No significant financial relationships to disclose.