Low Relapse Rate after 2 Years in Patients with Diffuse Large B-Cell Lymphoma (DLBCL) Treated with R-CHOP and Achieved Complete Response

Introduction: Patients with DLBCL usually relapse early after the first treatment but some relapse after 2 years (defined as late relapses). In a previous study, patients with DLBCL who achieved event free survival at 24 months had a subsequent overall survival equivalent to the general population. We analyzed the time of relapse and clinical characteristics of late relapse in patients with DLBCL who achieved complete response (CR) after frontline R-CHOP.

Methods: We retrospectively reviewed prospectively collected lymphoma registry of the Asan Medical Center in Seoul, Korea, between 2002 and 2015. We found 1,047 DLBCL patients who have been treated with R-CHOP as the first line modality. Among 1,047 patients, 859 (82.0%) patients achieved CR. Chi-square or Fisher's exact test was used for comparison of categorical variables and Student's t-test or Mann-Whitney U-test for continuous variables, as appropriate. Two-sided p-value of <0.05 was considered significant.

Results: Among 859 patients, 182 (21.2%) patients relapsed and 51 (5.9%) patients had late relapse after 2 years from the end of treatment evaluation that confirmed CR. For patients who had a late relapse, median time from diagnosis to relapse was 4.0 years (range, 2.0 to 10.0 years), median age was 61 years old (range, 39-78), and 27 (52.9%) patients were male. Twenty-six (51%) patients had stage I-II, and 36 (70.6%) patients had low/low-intermediate International Prognostic Index (IPI) score at diagnosis. Compared with early relapses (n=131, 12.5%), late relapses were associated with low IPI score (median, 2 vs. 3; p = 0.001), low LDH (median, 244 vs. 337 IU/L; p < 0.001), low beta-2-microglobulin (median, 2.4 vs. 2.6 mg/L p = 0.002), higher germinal center phenotype rate (30.6% vs. 15%; p=0.05). Median overall survival from the end of treatment evaluation that confirmed CR was significantly higher in the late relapse group compared with early relapse group [112.6 months (95% CI 73.1-152.0) vs. 19.9 months (95% CI 15.3-24.4); p<0.001 by log rank].

Conclusion: Our study demonstrated that relapse rate after 2 years was low (5.9%) in patients with DLBCL who achieved CR after R-CHOP. Patient with late relapse showed favorable clinical characteristics and survival outcomes compared with patients with early relapse.