You Make the Call: Can I start cytoreductive therapy in a patient with low-risk polycythemia vera?

Ayalew Tefferi, MD
Professor of Hematology/Oncology, Mayo Clinic, Rochester, Minnesota

This month, Ayalew Tefferi, MD, discusses cytoreductive therapy in a patient with low-risk polycythemia vera.

And don’t forget to check out next month’s clinical dilemma – send in your responses for a chance to win an ASH Clinical News-themed prize!


I am caring for a 39-year-old female patient with polycythemia vera (PV), who has required intermittent phlebotomy to keep her hematocrit level below 45%. JAK2 V617F mutation is present at 34% variant allele frequency. She has a persistently high white blood count and her highest neutrophil count has been 14,000/mm3. She also has a platelet count of 1.4 million/µL. She has essential hypertension controlled with antihypertensive medication, and her myeloproliferative neoplasm symptom assessment score is 0. What are the criteria to start cytoreductive therapy in a low-risk patient?


The case concerns a young woman with PV currently on treatment with phlebotomy with a target hematocrit level of 45%. The patient has mild leukocytosis, which is seen in about 50% of patients with PV, and extreme thrombocytosis, which is seen in about 4% of patients.1 Risk factors for poorer survival in PV include advanced age, abnormal karyotype, leukocytosis and presence of SRSF2 mutation.2 However, current PV treatment is based on risk for thrombosis and includes “high” (thrombosis history or age >60 years) or “low” (absence of both risk factors). Extreme thrombocytosis has not been shown to increase the risk of thrombosis in either PV or essential thrombocythemia. Similarly, the independent contribution of leukocytosis or cardiovascular risk factors to the risk of thrombosis is not high enough to warrant the addition of cytoreductive therapy to once- or twice-daily aspirin therapy, which is the preferred treatment strategy.


  1. Tefferi A, Rumi E, Finazzi G, et al. Survival and prognosis among 1,545 patients with contemporary polycythemia vera: an international study. Leukemia. 2013;27(9):1874-1881.
  2. Tefferi A, Guglielmelli P, Lasho TL, et al. Mutation-enhanced international prognostic systems for essential thrombocythaemia and polycythaemia vera. Br J Haematol. 2020;189(2):291-302.

How did readers respond? Check out You Make the Call – Readers’ Response.


I am caring for a female patient with obesity (>120 kg) who had an unprovoked saddle submassive pulmonary embolism that required thrombolytic therapy. I am wondering whether to use the maintenance dose of rivaroxaban 10 mg, or apixaban 2.5 mg twice per day. What would you recommend regarding use of the new oral anticoagulants for this patient?

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