...One of the following conditions must be met to be included in the study: (1) The longest diameter of the mass assessed by CT or PET/CT is >=10 cm; (2) International Prognostic Index (IPI) >= 2 points; (3) There are more than 2 extranodal lesions; (4) Involvement of the central nervous system; (5) Secondary to the second tumor or combined with the second tumor; (6) Genetic abnormalities or molecular biological abnormalities with known poor prognosis, such as P53 gene mutation, MYD88/CD79B mutation, c-MYC/BCL2 double expression, c-MYC/BCL-2/BCL-6 double strike or triple strike; (7) CNS-IPI score >= 2 points; 5. ...