Prognosis

Median overall survival (all ages) for patients with PMF was 4.0 years, based on registry data for 3689 PMF patients diagnosed between 2001 and 2015 (median follow-up 5.8 years). During the study period, 122 (3.3%) PMF patients progressed to acute myeloid leukaemia (AML); median time to AML transformation was 2.3 years.[86]

Median overall survival (stratified by age) has been estimated to be:[87]

  • 20 years (age ≤40 years)

  • 8 years (age 41-60 years)

  • 3 years (age >60 years)

Adverse prognostic factors include age at onset (>64 years), anaemia (Hb <100 g/L [<10 g/dL]), constitutional symptoms, white blood cell count abnormalities (<4 ×10⁹/L or >12 × 10⁹/L [<4000/microlitre or >12,000/microlitre]), thrombocytopenia, circulating blast cells (>1%), and certain cytogenetic abnormalities (-5/del5q, -7/del7q, trisomy 8, 12p-).[11][43]

Mutations in CALR are associated with improved overall survival compared with JAK2 V617F or MPL W515 mutations.[19]​ Type 1 CALR mutations (52-bp deletion) are more common, and have a more favourable impact on prognosis than type 2 CALR mutations (5-bp insertion) in PMF.[20][21]

Triple-negative mutation status (negative for JAK2, CALR, or MPL mutations) is associated with a worse prognosis in patients with PMF.[19][26]​​

ASXL1, EZH2, SRSF2, TP53, IDH1, IDH2, and U2AF1 mutations are considered high-molecular-risk mutations, associated with shorter overall and leukaemia-free survival.​[26][27]

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