title: Long-term outcome of 231 patients with essential thrombocythemia: prognostic factors for thrombosis, bleeding, myelofibrosis, and leukemia.
abstract: BACKGROUND
  Essential thrombocythemia (ET) is a clonal myeloproliferative disease associated with thrombohemorrhagic complications and myeloid transformation to diseases such as myelofibrosis and acute myeloid leukemia.
  
  
  METHODS
  A multicenter study was conducted among 231 consecutive Chinese patients with ET. The literature about leukemogenic risk associated with the use of hydroxyurea therapy was reviewed.
  
  
  RESULTS
  The median patient age was 65 years. Thrombosis rates at and after diagnosis of ET were comparable to those of white patients, but bleeding rates at and after diagnosis were much lower. The projected 10-year thrombosis-free, bleeding-free, and overall survival rates were 66%, 83%, and 80%, respectively. There were no deaths among patients 60 years or younger during a maximum follow-up of 15 years, and splenomegaly at diagnosis of ET appeared to protect against thrombosis. In multivariate analysis, advanced age predicted inferior 10-year thrombosis-free and overall survival, and male sex predicted inferior bleeding-free survival. Half the deaths were related to ET. The probability of myelofibrosis transformation was 9.7% at 10 years. Prior myelofibrosis (P = .008) and the use of melphalan treatment (P = .002) were risk factors for acute myeloid leukemia evolution.
  
  
  CONCLUSIONS
  Essential thrombocythemia is a benign disease of older persons. Chinese patients have a low risk of bleeding, and prior myelofibrosis is a major risk factor for evolution to acute myeloid leukemia. Leukemic transformation with hydroxyurea therapy alone is rare and warrants further prospective studies.
authors.affiliation: Department of Medicine, Queen Mary Hospital, University of Hong Kong, 102 Pokfulam Road, Hong Kong, ROC. jcschim@hkucc.hku.hk
authors.forename: Chor-Sang
authors.initials: CS
authors.lastname: Chim
authors.forename: Yok-Lam
authors.initials: YL
authors.lastname: Kwong
authors.forename: Albert Kwok-Wei
authors.initials: AK
authors.lastname: Lie
authors.forename: Siu-Kwan
authors.initials: SK
authors.lastname: Ma
authors.forename: Chi-Chung
authors.initials: CC
authors.lastname: Chan
authors.forename: Lap-Gate
authors.initials: LG
authors.lastname: Wong
authors.forename: Bonnie Chi San
authors.initials: BC
authors.lastname: Kho
authors.forename: Harold-Kwok
authors.initials: HK
authors.lastname: Lee
authors.forename: Joycelyn Pui-Yin
authors.initials: JP
authors.lastname: Sim
authors.forename: Cheuk-Hung
authors.initials: CH
authors.lastname: Chan
authors.forename: Joyce Chee-Wun
authors.initials: JC
authors.lastname: Chan
authors.forename: Yiu-Ming
authors.initials: YM
authors.lastname: Yeung
authors.forename: Martin
authors.initials: M
authors.lastname: Law
authors.forename: Raymond
authors.initials: R
authors.lastname: Liang
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use; D044466:Asian People; D002471:Cell Transformation, Neoplastic; D005260:Female; D005500:Follow-Up Studies; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D006918:Hydroxyurea / Q000627:therapeutic use; D007951:Leukemia, Myeloid / Q000453:epidemiology* / Q000473:pathology; D008297:Male; D008558:Melphalan / Q000627:therapeutic use; D008875:Middle Aged; D015999:Multivariate Analysis; D019653:Myeloablative Agonists / Q000627:therapeutic use; D055728:Primary Myelofibrosis / Q000453:epidemiology*; D011379:Prognosis; D012307:Risk Factors; D012737:Sex Factors; D013163:Splenomegaly; D016019:Survival Analysis; D013920:Thrombocythemia, Essential / Q000150:complications / Q000188:drug therapy / Q000401:mortality*; D013927:Thrombosis / Q000453:epidemiology*; D017086:beta-Thalassemia / Q000453:epidemiology
chemical_list: D000970:Antineoplastic Agents; D019653:Myeloablative Agonists; D008558:Melphalan; D006918:Hydroxyurea