Dose-Reduced Consolidation Radiation Therapy in Patients With Diffuse Large B-cell Lymphoma

Inclusion Criteria: * Histologic documentation of stage I-IV diffuse large B-cell lymphoma, not otherwise specified (DLBCL NOS), as defined by the 2016 WHO classification. This would include all entities within this category including germinal center B-cell and non-germinal center B-cell subtypes and those with a double expressor phenotype. Also eligible are stage I-IV high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements and high-grade B-cell lymphoma, NOS * Completion of at least 3 cycles of rituximab-containing, anthracycline-based combination chemotherapy * Negative post-chemotherapy PET-CT scan or negative interim PET-CT scan performed within 2 weeks of the final cycle of chemoimmunotherapy. This is defined as a score of 1-3 on the PET Five Point (Deauville) Scale using the Modified Lugano Response Criteria for Non-Hodgkin's Lymphoma * Absolute neutrophil count greater than 1000 and platelet count greater than 40,000 * Negative pregnancy test in women of child-bearing potential * Signed study specific informed consent Exclusion Criteria: * Primary central nervous system lymphoma, primary cutaneous DLBCL, leg type. T-cell/histiocyte-rich large B-cell lymphoma, primary mediastinal (thymic) large B-cell lymphoma, or other distinct non-Hodgkin lymphomas arising from large B-cells included in the WHO classification * Any absolute contraindications to irradiation