title: Radiation therapy in primary mediastinal B-cell lymphoma with positron emission tomography positivity after rituximab chemotherapy.
abstract: OBJECTIVE
  To investigate the role of radiation therapy (RT) in patients affected with primary mediastinal B-cell lymphoma (PMBCL) with residual (18)fluorodeoxyglucose positron emission tomography ((18)FDG-PET)-positive disease after rituximab chemotherapy (R-CT).
  
  
  METHODS
  Thirty-seven patients treated with R-CT and RT, all with (18)FDG-PET scan at diagnosis and before RT, were included. All (18)FDG-PET scans were reviewed, and responses were classified according to the Deauville 5-point scoring system. Outcomes measures were overall survival (OS) and progression-free survival (PFS), estimated for the whole cohort and for subgroups according to (18)FDG-PET score after R-CT.
  
  
  RESULTS
  The median follow-up time was 40.9 months. Three patients were assigned to Deauville score 1 (8.1%), 9 to score 2 (24.3%), 7 to score 3 (19%), 14 to score 4 (37.8%), and 4 to score 5 (10.8%). After RT, all patients with score 3-4 experienced a complete response (CR). Among patients with score 5, 1 was in CR (25%), 2 had persistent positivity (50%), and 1 showed progressive disease (25%). A total of 4 patients experienced progression or relapse: 1 of 33 (3%) with scores 1-4, and 3 of 4 (75%) with score 5. The 3-year OS and PFS of the whole cohort were 89.8% and 88.7%, respectively. OS was significantly different between scores 1-3 and scores 4-5 (100% vs 77% at 3 years, P<.05). Patients with a score of 5 had a significantly worse outcome than did all other patients (OS at 2 years, 33.3% vs 100%).
  
  
  CONCLUSIONS
  Approximately 50% of PMBCL patients show residual disease at (18)FDG-PET scan after R-CT. RT is able to convert to CR approximately 85% of these patients, but those with a Deauville score of 5 (10%) appear at high risk of progression and death, and they might be candidates for intensified programs.
authors.affiliation: Department of Oncology, University of Torino, Torino, Italy. andreariccardo.filippi@unito.it
authors.forename: Andrea Riccardo
authors.initials: AR
authors.lastname: Filippi
authors.forename: Cristina
authors.initials: C
authors.lastname: Piva
authors.forename: Francesca
authors.initials: F
authors.lastname: Giunta
authors.forename: Marilena
authors.initials: M
authors.lastname: Bellò
authors.forename: Annalisa
authors.initials: A
authors.lastname: Chiappella
authors.forename: Daniele
authors.initials: D
authors.lastname: Caracciolo
authors.forename: Michela
authors.initials: M
authors.lastname: Zotta
authors.forename: Anastasios
authors.initials: A
authors.lastname: Douroukas
authors.forename: Riccardo
authors.initials: R
authors.lastname: Ragona
authors.forename: Umberto
authors.initials: U
authors.lastname: Vitolo
authors.forename: Gianni
authors.initials: G
authors.lastname: Bisi
authors.forename: Umberto
authors.initials: U
authors.lastname: Ricardi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D058846:Antibodies, Monoclonal, Murine-Derived / Q000627:therapeutic use; D000970:Antineoplastic Agents / Q000627:therapeutic use; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D016393:Lymphoma, B-Cell / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000401:mortality / Q000532:radiotherapy*; D008297:Male; D008479:Mediastinal Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000401:mortality / Q000532:radiotherapy*; D008875:Middle Aged; D018365:Neoplasm, Residual; D049268:Positron-Emission Tomography / Q000379:methods; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D000069283:Rituximab; D055815:Young Adult
chemical_list: D058846:Antibodies, Monoclonal, Murine-Derived; D000970:Antineoplastic Agents; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D000069283:Rituximab