This protocol addresses essential thrombocythemia in patients who have experienced a prior venous thrombosis, at any age. A documented history of venous thrombosis is one of the key criteria that places a patient in the high-risk tier of ET — the tier that calls for the most proactive management strategy.
ET management begins with thrombosis risk stratification. The high-risk category includes patients with a history of thrombosis regardless of age, as well as patients older than 60 years who carry a JAK2 mutation. A prior venous thrombotic event alone is sufficient to classify a patient as high-risk.
High-risk ET with a history of venous thrombosis requires a combined approach: cytoreductive therapy is indicated, together with systemic anticoagulation. Depending on the presence of specific patient characteristics, additional antithrombotic coverage may be added to the regimen.
The primary clinical goal is to keep the platelet count within the normal range and maintain it there over the course of treatment.
Figure 5 outlines our general treatment approach in ET, which starts with thrombosis risk stratification: very low (age ≤60 years, no thrombosis history, JAK2 wild-type), low (same as very low but JAK2 mutation present), intermediate (age >60 years, no thrombosis history, JAK2 wild-type), and high (thrombosis history present or age >60 years with JAK2 mutation).
In patients with venous thrombosis, systemic anticoagulation is advised and the addition of once-daily low-dose aspirin, in the presence of JAK2 mutation or CV risk factors, is reasonable.
In addition to low-dose aspirin, high-risk patients with ET should receive HU, as first-line cytoreductive drug of choice, in order to minimize their risk of thrombosis (starting dose 500 mg BID).
The dose of HU is titrated to keep platelet count in the normal range.
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