title: Staging of chronic myeloid leukemia in the imatinib era: an evaluation of the World Health Organization proposal.
abstract: BACKGROUND
  Several staging classification systems, all of which were designed in the preimatinib era, are used for chronic myeloid leukemia (CML). The World Health Organization (WHO) recently proposed a new classification system that has not been validated clinically. The authors investigated the significance of the WHO classification system and compared it with the classification systems used to date in imatinib trials ("standard definition") to determine its impact in establishing the outcome of patients after therapy with imatinib.
  
  
  METHODS
  In total, 809 patients who received imatinib for CML were classified into chronic phase (CP), accelerated phase (AP), and blast phase (BP) based on standard definitions and then were reclassified according to the new WHO classification system. Their outcomes with imatinib therapy were compared, and the value of individual components of these classification systems was determined.
  
  
  RESULTS
  With the WHO classification, 78 patients (10%) were reclassified: 45 patients (6%) were reclassified from CP to AP, 14 patients (2%) were reclassified from AP to CP, and 19 patients (2%) were reclassified from AP to BP. The rates of complete cytogenetic response for patients in CP, AP, and BP according to the standard definition were 72%, 45%, and 8%, respectively. After these patients were reclassified according to WHO criteria, the response rates were 77% (P = 0.07), 39% (P = 0.28), and 11% (P = 0.61), respectively. The 3-year survival rates were 91%, 65%, and 10%, respectively, according to the standard classification and 95% (P = 0.05), 63% (P = 0.76), and 16% (P = 0.18), respectively, according to the WHO classification. Patients who had a blast percentage of 20-29%, which is considered CML-BP according to the WHO classification, had a significantly better response rate (21% vs. 8%; P = 0.11) and 3-year survival rate (42% vs. 10%; P = 0.0001) compared with patients who had blasts > or = 30%.
  
  
  CONCLUSIONS
  Different classification systems had an impact on the outcome of patients, and some prognostic features had different prognostic implications in the imatinib era. The authors believe that a new, uniform staging system for CML is warranted, and they propose such a system.
authors.affiliation: Department of Leukemia, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA. jcortes@mdanderson.org
authors.forename: Jorge E
authors.initials: JE
authors.lastname: Cortes
authors.forename: Moshe
authors.initials: M
authors.lastname: Talpaz
authors.forename: Susan
authors.initials: S
authors.lastname: O'Brien
authors.forename: Stefan
authors.initials: S
authors.lastname: Faderl
authors.forename: Guillermo
authors.initials: G
authors.lastname: Garcia-Manero
authors.forename: Alessandra
authors.initials: A
authors.lastname: Ferrajoli
authors.forename: Srdan
authors.initials: S
authors.lastname: Verstovsek
authors.forename: Mary B
authors.initials: MB
authors.lastname: Rios
authors.forename: Jenny
authors.initials: J
authors.lastname: Shan
authors.forename: Hagop M
authors.initials: HM
authors.lastname: Kantarjian
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D001549:Benzamides; D005260:Female; D006801:Humans; D000068877:Imatinib Mesylate; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000145:classification / Q000188:drug therapy / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D010879:Piperazines / Q000627:therapeutic use*; D011379:Prognosis; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D011743:Pyrimidines / Q000627:therapeutic use*; D012074:Remission Induction; D015996:Survival Rate; D016896:Treatment Outcome; D014944:World Health Organization
chemical_list: D000970:Antineoplastic Agents; D001549:Benzamides; D010879:Piperazines; D011743:Pyrimidines; D000068877:Imatinib Mesylate; D011505:Protein-Tyrosine Kinases