Prognostic significance of primary extranodal diffuse large B-cell lymphoma (DLBCL) in patients treated with R-CHOP

Abstract

8583 Background: Previous studies in the pre-rituximab era have identified important clinical differences between nodal and primary extranodal DLBCL. We have examined the prognostic significance of primary extranodal DLBCL in the post-rituximab era. Methods: Using the Lymphoid Cancer Database of the British Columbia Cancer Agency, all patients ≥18 years of age diagnosed with DLBCL between January 1999 and May 2006 and treated with an R-CHOP regimen were included for analysis. Patients were excluded if they were HIV positive, presented with disease in the testicular or central nervous system, or had known coincident indolent lymphoma. Primary extranodal DLBCL was defined as disease confined to one or more localized extranodal sites, with no or minimal nearby nodal involvement. Results: 513 patients were identified with the following characteristics: median age 62 y (range 19–93), male 59.1%, stage III/IV 53.8%, elevated LDH 49.5%, and performance status ≥2 38.2%. While 350 (68.2%) had at least some degree of extranodal involvement, only 133 (25.9%) had primary extranodal DLBCL. Among patients with primary extranodal disease, 70 (52.6%), 37 (27.8%) and 26 (19.6%) had 1, 2 and ≥3 extranodal sites, respectively. The most commonly involved extranodal sites included bone (33.1%), soft tissue (28.6%), stomach (15.0%), intestine (12.8%), and sinus (10.5%). Thirty-two percent, 20%, 0% and 48% of patients with primary extranodal DLBCL had stage I, II, III, and IV, respectively. This is in contrast to 11%, 34%, 26% and 29% for the nodal DLBCL group. Primary extranodal DLBCL was less commonly associated with an elevated LDH (37.6% vs. 53.7%, p=0.001). The distribution of International Prognostic Index scores was similar between the two groups. With a median follow-up of 2.8 years, no significant difference in overall survival was detected between primary extranodal DLBCL and nodal DLBCL analyzed either as a group or by individual stages. Furthermore, we did not identify any specific primary extranodal sites that confer a worse prognosis. Conclusion: In the post-rituximab era, the previously identified survival difference in primary extranodal DLBCL is no longer observed in this large cohort. No significant financial relationships to disclose.