Prognostic factors for thrombosis, myelofibrosis, and leukemia in essential thrombocythemia: a study of 605 patients.
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.
Passamonti
Francesco
F
M.D., Division of Hematology, University of Pavia, Fondazione IRCCS Policlinico San Matteo, viale Golgi 19, 27100 Pavia, Italy. f.passamonti@smatteo.pv.it
Rumi
Elisa
E
Arcaini
Luca
L
Boveri
Emanuela
E
Elena
Chiara
C
Pietra
Daniela
D
Boggi
Sabrina
S
Astori
Cesare
C
Bernasconi
Paolo
P
Varettoni
Marzia
M
Brusamolino
Ercole
E
Pascutto
Cristiana
C
Lazzarino
Mario
M
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
C507924:JAK2 protein, human; D053614:Janus Kinase 2