title: The Follicular Lymphoma International Prognostic Index (FLIPI) and the histological subtype are the most important factors to predict histological transformation in follicular lymphoma.
abstract: BACKGROUND
  Histological transformation (HT) is a well-known event in patients with follicular lymphoma (FL) conferring an unfavorable prognosis. The aim of the study was to analyze incidence and risk factors for HT in a large series of FL patients.
  
  
  METHODS
  276 patients (median age: 54 years; M139/F137) diagnosed with FL (42% grade 1, 51% 2, 7% 3) in a single institution were studied. Initial treatment consisted of combined chemotherapy in most cases. Median survival was 11.3 years. Main clinic and biological variables were assessed for HT and survival.
  
  
  RESULTS
  30 of 276 patients (11%) presented HT after a median follow-up of 6.5 years, with a risk of 15% and 22% at 10 and at 15 years, respectively. All HT corresponded to diffuse large B-cell lymphoma (DLBCL). Grade 3 histology, nodal areas >4, increased LDH and beta(2)-microglobulin, and high-risk IPI and FLIPI were associated with HT. In multivariate analysis, grade 3 histology and FLIPI retained prognostic significance. Only FLIPI predicted HT in grade 1-2 patients. 28 patients received salvage treatment for HT, with a CR rate of 52%. Median survival from transformation was 1.2 years, with 6/13 CR patients being alive >5 years after HT.
  
  
  CONCLUSIONS
  FLIPI and histology were the most important variables predicting HT. Upon HT, only patients achieving CR reached prolonged survival, thus emphasizing the need for effective therapies once this event occurs.
authors.affiliation: Institute of Hematology and Oncology, Department of Hematology and Hematopathology Unit, Hospital Clínic, IDIBAPS, Barcelona, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Giné
authors.forename: S
authors.initials: S
authors.lastname: Montoto
authors.forename: F
authors.initials: F
authors.lastname: Bosch
authors.forename: L
authors.initials: L
authors.lastname: Arenillas
authors.forename: S
authors.initials: S
authors.lastname: Mercadal
authors.forename: N
authors.initials: N
authors.lastname: Villamor
authors.forename: A
authors.initials: A
authors.lastname: Martínez
authors.forename: L
authors.initials: L
authors.lastname: Colomo
authors.forename: E
authors.initials: E
authors.lastname: Campo
authors.forename: E
authors.initials: E
authors.lastname: Montserrat
authors.forename: A
authors.initials: A
authors.lastname: López-Guillermo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002471:Cell Transformation, Neoplastic / Q000473:pathology*; D018450:Disease Progression; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D015994:Incidence; D008224:Lymphoma, Follicular / Q000175:diagnosis* / Q000453:epidemiology / Q000401:mortality / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D016019:Survival Analysis