A Multicenter, Phase 2 Study Evaluating the Value of Radiotherapy in Advanced Diffuse Large B-cell Lymphoma Patients With Extranodal Involvement and Large Tumors Undergoing Immunochemotherapy for PET-CT Assessment of Complete Remission

All enrolled patients will first complete a total of 6-8 cycles (21 days per cycle) of Standard R-CHOP chemotherapy (Rituximab + Cyclophosphamide + Doxorubicin + Prednisolone) and conduct evaluation about treatment effects (i.e. efficacy evaluation) once every 2 cycles, and after their completion of the 6th cycle, they will receive maintenance treatment . After the end of 6th cycle of treatment or after their leaving the group, efficacy evaluation is conducted every three months to obtain relevant data regarding the 2-year Progression-Free Survival(PFS) and survival of the subjects.

Radiotherapy: after completion of the standard R-CHOP treatment, enrolled patients will be divided into radiotherapy group and non-radiotherapy group. In radiotherapy group, further consolidation radiotherapy targeting patients' pre-treatment large masses or extranodal affected areas will be given, with routine segmentation of 30-36Gy/15-18f.