Management of Very Low Risk Essential Thrombocythemia

Primary Recommendation

The National Comprehensive Cancer Network recommends that very low-risk ET patients (age ≤60 years, no JAK2 mutation, no prior thrombosis) be managed with observation without any treatment, including no aspirin and no cytoreductive therapy 1, 2

The revised IPSET-Thrombosis score defines very low-risk ET by three specific criteria, and this risk category has a thrombotic risk similar to that of the general population, with an incidence of 1.91 thrombotic events per 100 patient-years 1, 2

The National Comprehensive Cancer Network recommends that aspirin is not used for asymptomatic very low-risk ET patients, as the absence of JAK2 mutation means lower thrombotic risk, and retrospective analyses suggest aspirin may increase bleeding risk without reducing thrombosis in CALR-mutated patients 1, 3, 4, 2
The American College of Hematology suggests that regular surveillance for very low-risk ET patients should focus on complete blood counts to track platelet trends and detect progression, new thrombotic events, acquired von Willebrand disease, disease-related major bleeding, and cardiovascular risk factors that may shift risk category 1, 3

Treatment should be initiated if new thrombotic events, microvascular symptoms, symptomatic or progressive splenomegaly, platelet count exceeding 1,500 × 10⁹/L, or progressive leukocytosis or disease-related symptoms occur 1, 3, 4, 5, 2

The presence of JAK2 mutation fundamentally changes management, and low-risk ET patients (age ≤60, JAK2-mutated, no prior thrombosis) should receive aspirin 81-100 mg daily, whereas very low-risk patients (JAK2 wild-type) should not 1, 2, 3

The National Comprehensive Cancer Network advises against reflexively prescribing aspirin based solely on elevated platelet count, as the platelet count itself does not mandate treatment in very low-risk patients without symptoms or JAK2 mutation 1, 3
The Journal of Clinical Oncology recommends that cytoreductive therapy should not be initiated for asymptomatic very low-risk disease, as hydroxyurea and other cytoreductive agents carry leukemogenic risk and should be reserved for patients who develop high-risk features or symptomatic disease 4, 1, 5, 2