Survival Outcomes of Limited-Stage Diffuse Large B-Cell Lymphoma Treated With Radiation Therapy

Background: Patients with favorable risk limited-stage (LS) diffuse large b-cell lymphoma (DLBCL) have shown excellent outcomes without radiotherapy (RT). However, the role of RT for the remainder of LS-DLBCL patients is less well defined. We aimed to investigate whether the addition of RT provided an overall survival (OS) benefit in a real-world cohort of LS-DLBCL patients based on primary site at presentation. Materials and Methods: Retrospective data from 39,745 patients with stage I and II DLBCL treated with front-line combination chemotherapy alone or followed by RT were identified using the National Cancer Database from 2004 to 2015. Results: The addition of RT was associated with improved 5-year OS for all LS patients as compared to those treated with chemotherapy alone (85% vs. 80%, P < .001). RT was associated with improved 5-year OS in both the nodal and extranodal disease patients (nodal: 85% vs. 80%, P < .001; extranodal: 83% vs. 79%; P < .001). Extranodal sites with prolonged OS from the addition of RT include skin and soft tissue, head and neck, testicular, and thyroid sites (all P < .02). Breast, bone, lung and gastrointestinal extranodal primary sites had no OS benefit from the inclusion of RT. In multivariate analysis, the addition of RT was an independent factor for improved survival for all LS patients ([HR] 0.84, 95% [CI] 0.81-0.88; P < .001). Conclusion: Though there is no consensus on optimal treatment indications for RT in LS-DLBCL, these data suggest certain subgroups may have benefit when RT is added to front-line chemotherapy.