Prospective studies indicate that the risk of microvascular and major
thrombosis in untreated
thrombocythemia in various myeloproliferative
neoplasms (MPN-T) is not age dependent and causally related to platelet-mediated
thrombosis in early, intermediate and advanced stages of
thrombocythemia in MPN-T. If left untreated both microvascular and major
thrombosis frequently do occur in MPN-T, but can easily be cured and prevented by low dose
aspirin as platelet counts are above 350 × 10(9)/L. The thrombotic risk stratification in the retrospective Bergamo study has been performed in 100
essential thrombocythemia (ET) patients not treated with
aspirin thereby overlooking the discovery in 1985 of
aspirin responsive platelet-mediated arteriolar and arterial thrombotic tendency in MPN-T disease of ET and
polycythemia vera (PV) patients. The Bergamo definition of high thrombotic risk and its persistence in the 2012 International Prognostic Score for ET is based on statistic mystification and not applicable for low and intermediate MPN-T disease burden in ET and PV patients on
aspirin. With the advent of molecular screening of MPN patients, MPN-T disease associated with significant
leukocytosis,
thrombocytosis, constitutional symptoms and/or moderate
splenomegaly are candidates for low dose peglyated
interferon (
Pegasys(R), 45 μg/mL once per week or every two weeks) as the first line myeloreductive treatment option in JAK2(V617F) mutated MPN-T disease in ET and PV patients. If non-responsive to or side effects induced by IFN,
hydroxyurea is the second line myelosuppressive treatment option in JAK2(V617F) mutated ET and PV patients with increased MPN-T disease burden.