Combined-Modality Therapy for Early-Stage Diffuse Large B-Cell Lymphoma: Knowing When to Quit

Patient Survival With and Without Radiation Therapy for Early-Stage Diffuse Large B-Cell Lymphoma in the Era of PET and Rituximab

Purpose

The benefit of radiation therapy (RT) becomes uncertain in the treatment of early stage diffuse large B-cell lymphoma (DLBCL) in the era of rituximab, positron emission topography (PET), and computed tomography (CT). We sought to retrospectively review modern patients with early stage I-II DLBCL treated with rituximab and staged by PET-CT to better define which patients benefit from consolidative RT.

Methods and Materials

Patients with early stage I-II DLBCL from 1998 to 2017 were reviewed coinciding with our institutional utilization of rituximab with the standard regimen of cyclophosphamide, doxorubicin, vincristine, and prednisone and PET-CT. Relevant clinical information was used to calculate National Comprehensive Cancer Network international prognostic index (IPI) scores. Kaplan-Meier survival analysis and a Cox proportional hazards model were used for overall survival (OS).

Results

Seventy-seven patients received chemoimmunotherapy alone, and 41 received chemoimmunotherapy plus RT. Median follow-up time was 9.5 years. On univariate analysis, extranodal disease (P = .04) and National Comprehensive Cancer Network IPI (P < .001) were significantly correlated with OS. Five-year OS was 87% versus 67%, and 10-year OS was 67% versus 58%, numerically higher favoring RT (P = .16). On multivariate Cox regression analysis of OS controlling for IPI and extranodal disease, the addition of RT was associated with improved OS (hazard ratio of 0.4, P = .01).

Conclusions

The current analysis supports the use of consolidative RT in early stage DLBCL given an OS benefit on multivariate analysis. Further prospective randomized data are needed to confirm these findings.

Improving outcomes in limited-stage de novo CD5+ DLBCL: systemic approaches with consolidative radiation

CD5-positive diffuse large B-cell lymphoma (CD5+ DLBCL) is characterized by poor prognosis after frontline immunochemotherapy. This retrospective study investigated the effect of consolidative radiation after systemic treatment in newly diagnosed stage I-II de novo CD5+ DLBCL. In this study, 22 patients received consolidative radiotherapy (RT) after immunochemotherapy (chemotherapy + RT group) and 28 patients received chemotherapy alone. Patients who received chemotherapy alone had a significantly shorter PFS and OS than those who received consolidative radiotherapy. The five-year PFS rates for the chemotherapy + RT and chemotherapy alone groups were 75.1% and 40.5%, respectively. The five-year OS rates for the chemotherapy + RT and chemotherapy alone groups were 84.2% and 50.1%, respectively. Even after receiving consolidation radiotherapy, 2/22 (9.1%) patients experienced CNS relapse. Age >60 years and lack of radiotherapy were independent prognostic factors for PFS and OS. Ki-67 (≥80%) was an independent prognostic factor for poor OS. Consolidative radiotherapy might be a good option for stage I-II CD5+ DLBCL, but further investigation is needed.

R-CHOP 14 with or without radiotherapy in nonbulky limited-stage diffuse large B-cell lymphoma

The benefit of radiotherapy (RT) after chemotherapy in limited-stage diffuse large B-cell lymphoma (DLBCL) remains controversial. We conducted a randomized trial in patients with nonbulky limited-stage DLBCL to evaluate the benefit of RT after rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP). Patients were stratified according to the modified International Prognostic Index, including lactate dehydrogenase, Eastern Cooperative Oncology Group performance status, age, and disease stage. The patients received 4 or 6 consecutive cycles of R-CHOP delivered once every 2 weeks, followed or not by RT at 40 Gy delivered 4 weeks after the last R-CHOP cycle. All patients were evaluated by fluorodeoxyglucose-positron emission tomography scans performed at baseline, after 4 cycles of R-CHOP, and at the end of treatment. The primary objective of the trial was event-free survival (EFS) from randomization. The trial randomly assigned 165 patients in the R-CHOP arm and 169 in the R-CHOP plus RT arm. In an intent-to-treat analysis with a median follow-up of 64 months, 5-year EFS was not statistically significantly different between the 2 arms, with 89% ± 2.9% in the R-CHOP arm vs 92% ± 2.4% in the R-CHOP plus RT arm (hazard ratio, 0.61; 95% confidence interval [CI], 0.3-1.2; P = .18). Overall survival was also not different at 92% (95% CI, 89.5%-94.5%) for patients assigned to R-CHOP alone and 96% (95% CI, 94.3%-97.7%) for those assigned to R-CHOP plus RT (P = not significant). R-CHOP alone is not inferior to R-CHOP followed by RT in patients with nonbulky limited-stage DLBCL. This trial was registered at www.clinicaltrials.gov as #NCT00841945.

Diffuse Large B-Cell Lymphoma: Should Limited-Stage Patients Be Treated Differently?

Diffuse large B-cell lymphoma presents as limited-stage disease in approximately 30% of cases. Historically, therapy relied on a combined modality of abbreviated chemotherapy followed by involved-field radiotherapy (IFRT). Due to the apparent lack of long-term survival and the concern for delayed toxicity, chemotherapy-only strategies are used more frequently. Treatment should take into account patient performance, clinical risks, and involvement sites. PET-guided approaches are being investigated. The risk of late relapse has been recognized, highlighting the importance of long-term follow-up. Future efforts must incorporate biological features to improve risk assessment, guide clinical decisions, and achieve an individualized therapy.