title: 18F-FDG PET/CT for early response assessment in diffuse large B-cell lymphoma: poor predictive value of international harmonization project interpretation.
abstract: PET using (18)F-FDG has prognostic value when performed at the completion of initial chemotherapy in patients with diffuse large B-cell lymphoma (DLBCL). (18)F-FDG PET may also be predictive of outcome when performed during the treatment course of DLBCL, but robust prospective studies and standardization of (18)F-FDG PET interpretation in this setting are lacking.
  
  
  METHODS
  In this prospective study, patients with advanced-stage DLBCL were treated with standard rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone chemotherapy, and (18)F-FDG PET/CT was performed after cycle 2 or 3 and at the end of therapy. The (18)F-FDG PET/CT scans were interpreted according to the International Harmonization Project for Response Criteria in Lymphoma, and the maximum standardized uptake value (SUV) of the most (18)F-FDG-avid lesions was recorded.
  
  
  RESULTS
  Fifty patients were enrolled, and all underwent interim (18)F-FDG PET/CT. At a median follow-up of 33.9 mo, the positive predictive value (PPV) of interim (18)F-FDG PET/CT for relapse or progression was 42%, and the negative predictive value (NPV) was 77%. Interim (18)F-FDG PET/CT was significantly associated with event-free survival (P = 0.017) and with progression-free survival (P = 0.04) but not with overall survival (P = 0.08). End-of-therapy (18)F-FDG PET/CT had high PPV and NPV (71% and 80%, respectively) and was significantly associated with event-free survival, progression-free survival, and overall survival (P < 0.001). SUV measurements did not discriminate patients who relapsed or progressed from those who remained in remission.
  
  
  CONCLUSIONS
  When performed after 2 cycles of immunochemotherapy and interpreted according to International Harmonization Project criteria, early response assessment with PET/CT has a high NPV but low PPV in patients with advanced-stage DLBCL. Prospective trials are required to validate different criteria for the interpretation of interim (18)F-FDG PET/CT and establish the role of interim (18)F-FDG PET/CT in the management of patients with DLBCL.
authors.affiliation: Siteman Cancer Center, Washington University School of Medicine, St. Louis, MO, USA. acashen@dom.wustl.edu
authors.forename: Amanda F
authors.initials: AF
authors.lastname: Cashen
authors.forename: Farrokh
authors.initials: F
authors.lastname: Dehdashti
authors.forename: Jingqin
authors.initials: J
authors.lastname: Luo
authors.forename: Andrew
authors.initials: A
authors.lastname: Homb
authors.forename: Barry A
authors.initials: BA
authors.lastname: Siegel
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Bartlett
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D000970:Antineoplastic Agents / Q000008:administration & dosage; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage*; D003520:Cyclophosphamide / Q000008:administration & dosage; D004317:Doxorubicin / Q000008:administration & dosage / Q000031:analogs & derivatives; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D016393:Lymphoma, B-Cell / Q000175:diagnosis* / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011241:Prednisone / Q000008:administration & dosage; D011379:Prognosis; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D014750:Vincristine / Q000008:administration & dosage
chemical_list: D000970:Antineoplastic Agents; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D014750:Vincristine; D004317:Doxorubicin; D003520:Cyclophosphamide; D011241:Prednisone