title: Relationship between minimal residual disease measured by multiparametric flow cytometry prior to allogeneic hematopoietic stem cell transplantation and outcome in children with acute lymphoblastic leukemia.
abstract: BACKGROUND
  The presence of minimal residual disease detected by polymerase chain reaction techniques prior to allogeneic hematopoietic stem cell transplantation has proven to be an independent prognostic factor for poor outcome in children with acute lymphoblastic leukemia.
  
  
  METHODS
  The aim of this study was to ascertain whether the presence of minimal residual disease detected by multiparametric flow cytometry prior to allogeneic hematopoietic stem cell transplantation is related to outcome in children acute lymphoblastic leukemia. Minimal residual disease was quantified by multiparametric flow cytometry at a median of 10 days prior to hematopoietic stem cell transplantation in 31 children (age range, 10 months to 16 years) with acute lymphoblastic leukemia. Thirteen patients were transplanted in first remission. Stem cell donors were HLA-identical siblings in 8 cases and matched unrelated donors in 23. Twenty-six children received a total body irradiation-containing conditioning regimen. According to the level of minimal residual disease, patients were divided into two groups: minimal residual disease-positive (>or=0.01%) (n=10) and minimal residual disease-negative (<0.01%) (n=21).
  
  
  RESULTS
  Estimated event-free survival rates at 2 years for the minimal residual disease-negative and -positive subgroups were 74% and 20%, respectively (P=0.004) and overall survival rates were 80% and 20%, respectively (P=0.005). Bivariate analysis identified pre-transplant minimal residual disease as the only significant factor for relapse and also for death (P<0.01).
  
  
  CONCLUSIONS
  The presence of minimal residual disease measured by multiparametric flow cytometry identified a group of patients with a 9.5-fold higher risk of relapse and a 3.2-fold higher risk of death than those without minimal residual disease. This study supports the strong relationship between pre-transplantation minimal residual disease measured by multiparametric flow cytometry and outcome following allogeneic hematopoietic stem cell transplantation and concur with the results of previous studies using polymerase chain reaction techniques.
authors.affiliation: Department of Pediatric Hematology and Oncology Hospital Universitario Vall d'Hebron Paseig de la Vall d'Hebron 119-129 08035 Barcelona, Spain. ielorza@vhebron.net
authors.forename: Izaskun
authors.initials: I
authors.lastname: Elorza
authors.forename: Carlos
authors.initials: C
authors.lastname: Palacio
authors.forename: Jose Luis
authors.initials: JL
authors.lastname: Dapena
authors.forename: Laura
authors.initials: L
authors.lastname: Gallur
authors.forename: José
authors.initials: J
authors.lastname: Sánchez de Toledo
authors.forename: Cristina
authors.initials: C
authors.lastname: Díaz de Heredia
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D005434:Flow Cytometry / Q000379:methods*; D005500:Follow-Up Studies; D018380:Hematopoietic Stem Cell Transplantation / Q000379:methods*; D006801:Humans; D007223:Infant; D008297:Male; D018365:Neoplasm, Residual; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000401:mortality* / Q000532:radiotherapy / Q000601:surgery*; D012307:Risk Factors; D015996:Survival Rate / Q000639:trends; D014184:Transplantation, Homologous; D016896:Treatment Outcome; D014916:Whole-Body Irradiation / Q000639:trends