title: Prognostic factors for thrombosis, myelofibrosis, and leukemia in essential thrombocythemia: a study of 605 patients.
abstract: BACKGROUND
  Essential thrombocythemia is a chronic myeloproliferative disorder; patients with this disorder have a propensity to develop thrombosis, myelofibrosis, and leukemia.
  
  
  METHODS
  We studied 605 patients with essential thrombocythemia (follow-up 4596 person-years) with the aim of defining prognostic factors for thrombosis, myelofibrosis, and leukemia during follow-up.
  
  
  RESULTS
  Sixty-six patients (11%) developed thrombosis with a 10-year risk of 14%. Age >60 years (p<0.001) and a history of thrombosis (p=0.03) were independent risk factors for thrombosis. Progression to myelofibrosis occurred in 17 patients (2.8%) with a 10-year risk of 3.9%. Anemia at diagnosis of essential thrombocythemia was significantly correlated (p<0.001) with progression to myelofibrosis. Leukemia occurred in 14 patients (2.3%) at a median time of 11 years after the diagnosis of essential thrombocythemia; the risk was 2.6% at 10 years. Age >60 years (p=0.02) was significantly correlated with the development of leukemia. Cytotoxic treatment did not imply a higher risk of leukemia. At the time of the analysis, 64 of the 605 patients (10.6%) had died. The 10-year probability of survival was 88%, with a median survival of 22.3 years. Age >60 years (p<0.001) and history of thrombosis (p=0.001) were independent risk factors for survival.
  
  
  CONCLUSIONS
  The findings from this study on a large series of patients treated according to current clinical practice provide reassurance that essential thrombocythemia is an indolent disorder and affected patients have a long survival. The main risk is thrombosis, while myelofibrosis and leukemia are rare and late complications.
authors.affiliation: M.D., Division of Hematology, University of Pavia, Fondazione IRCCS Policlinico San Matteo, viale Golgi 19, 27100 Pavia, Italy. f.passamonti@smatteo.pv.it
authors.forename: Francesco
authors.initials: F
authors.lastname: Passamonti
authors.forename: Elisa
authors.initials: E
authors.lastname: Rumi
authors.forename: Luca
authors.initials: L
authors.lastname: Arcaini
authors.forename: Emanuela
authors.initials: E
authors.lastname: Boveri
authors.forename: Chiara
authors.initials: C
authors.lastname: Elena
authors.forename: Daniela
authors.initials: D
authors.lastname: Pietra
authors.forename: Sabrina
authors.initials: S
authors.lastname: Boggi
authors.forename: Cesare
authors.initials: C
authors.lastname: Astori
authors.forename: Paolo
authors.initials: P
authors.lastname: Bernasconi
authors.forename: Marzia
authors.initials: M
authors.lastname: Varettoni
authors.forename: Ercole
authors.initials: E
authors.lastname: Brusamolino
authors.forename: Cristiana
authors.initials: C
authors.lastname: Pascutto
authors.forename: Mario
authors.initials: M
authors.lastname: Lazzarino
mesh_terms: D000368:Aged; D018450:Disease Progression; D005500:Follow-Up Studies; D006801:Humans; D053614:Janus Kinase 2 / Q000235:genetics; D007938:Leukemia / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology*; D008875:Middle Aged; D009154:Mutation; D009196:Myeloproliferative Disorders / Q000235:genetics*; D055728:Primary Myelofibrosis / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology*; D011379:Prognosis; D012307:Risk Factors; D013920:Thrombocythemia, Essential / Q000150:complications*; D013927:Thrombosis / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology*; D013997:Time Factors
chemical_list: C507924:JAK2 protein, human; D053614:Janus Kinase 2