Localized Nodal Diffuse Large B Cell Lymphoma: Is Radiotherapy Needed?

Introduction: Diffuse large B-cell lymphoma (DLBCL) is clinically, morphologically and genetically a heterogeneous group of malignant proliferation of large B-cell lymphoid cells. At diagnosis, 25% of DLBCL presents as a localized disease.Therapeutic options for localized DLBCL include short-course or extended-course chemotherapy regimens such as R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone) with or without radiotherapy. Regarding the number of cycles, the choice differs in the different oncology services and the role of radiotherapy remains controversial. Another frequent issue regarding this pathology is the prognosis of the cell of origin (COO) in the localized form. In the literature, non-germ center (N-GC) subtype is correlated with lower overall survival (OS) when compared to germinal center (GC) . This lower overall survival of the non-GC subtype has not been reported in patients with localized DLBCL. Objectives: The primary objective is to compare progression-free survival (PFS) and overall survival (OS) at 5 years of different therapeutic strategies, including 3-4 cycles of chemotherapy with or without radiotherapy and 6 cycles of chemotherapy with or without radiotherapy. The study's secondary objective is to compare the prognostic significance of COO, GC and non-GC phenotypes in localized DLBCL. Methods: This is a single-center Brazilian, observational, retrospective, descriptive and analytical study, to be carried out at the referenced Brazilian cancer center, A.C. Camargo Cancer Center. The study included patients aged 18 years and over, with a nodal DLBCL diagnosis located in the period between 2007 and 2020. PFS and OS curves were performed in 5 years of the population stratified by treatment and cell of origin. Results: A total of 90 patients with limited-stage nodal DLBCL were included. The group that received 3 or 4 cycles of chemotherapy (n=5) had PFS and OS at 5 years of 75%. The second group received 6 cycles of chemotherapy (n=41) and had PFS and OS at 5 years of 89% and 92%, respectively. The third group (n=17) received 3 or 4 cycles of chemotherapy and radiotherapy, and had 100% PFS and OS at 5 years. The fourth group (n=27) received 6 cycles of chemotherapy and radiotherapy and had PFS and OS at 5 years of 87%. There was no statistical difference between the groups. A total of 76 patients had immunohistochemical data extracted from pathology reports to determine COO by Hans' algorithm. A GC phenotype was observed in 47% of patients (n=36). At 5 years, the PFS and OS for the GC cohort were 94% for both, and for the non-GC cohort 85% and 87% respectively. Conclusion: There was no significant difference in PFS or OS for the therapeutic strategies, including 3-4 cycles of chemotherapy with or without radiotherapy and 6 cycles of chemotherapy with or without radiotherapy. In this analysis, the cell of origin did not show a difference in 5 year PFS or OS for localized nodal DLBCL.

No relevant conflicts of interest to declare.