Abstract
Myelofibrosis (MF) represents the major long-term complication of essential thrombocythemia (ET). There is evidence that leukocytosis at diagnosis is associated with poorer survival in patients with ET. In this study, we retrospectively evaluated 143 patients with ET, diagnosed in agreement with WHO criteria, followed in a single centre over >10 years. Nine of them transformed into MF (post-essential thrombocythemia-myelofibrosis PET-MF). We compared PET-MF data at diagnosis with that of the remaining 134 patients (ET-1) and with a selected sub-group of ET-1 (ET-2, 19 pats) sex, age and follow-up duration matched to PET-MF. The PET-MF evolution rate was 4.6 per 1000 person-years; white blood cells count (WBC) count, haemoglobin levels and hematocrit were higher in PET-MF than in ET-1 (P = 0.01) while only WBC was higher than in ET-2 (P = 0.01). With multivariate analysis, only WBC count retained its signifi-cance. Our study highlights the prognostic relevance of leukocytosis on myelofibrotic transformation of ET.
Highlights
Among the classical myeloproliferative neoplasms (MPN), essential thrombocythemia (ET) has the most favourable prognosis in terms of survival and myelofibrosis or leukemic transformation: ET is considered usually not to reduce the patient’s life expectancy, with median survival ranging from 13 to 22.3 years [1]
white blood cells count (WBC) count, haemoglobin level and hematocrit at diagnosis were statistically higher in PET-MF than in ET-1
The threshold WBC count significant for PET-MF was identified at 10.2 × 109/L comparing with ET-1 and at 10 × 109/L comparing with ET-2
Summary
Among the classical myeloproliferative neoplasms (MPN), essential thrombocythemia (ET) has the most favourable prognosis in terms of survival and myelofibrosis or leukemic transformation: ET is considered usually not to reduce the patient’s life expectancy, with median survival ranging from 13 to 22.3 years [1]. The transition to MF represents the major long-term complication of ET with an estimated risk of about 5% at 10 years [4] and the transition to MF is considered a facilitating condition to the development of acute leukemia (AL). Leukocytosis has been published to be an adverse prognostic factor for leukemic transformation [5] and significant [6] or near-significant [7] associations in PV in this regard have previously been communicated as well. No meaningful difference between the presence of JAK2V617F mutation and the progression to PET-MF has been observed [8], even if in a large study [9] a greater risk of developing large splenomegaly and leukemia was found in JAK2V617F mutated PMF patients and the accumulation of mutant V617F alleles has been reported to be possibly associated to evolution of PV to MF [10]
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