Essential Thrombocythemia Risk, Prognosis, and Survival

Essential Thrombocythemia (ET) Is a Chronic Disease That May Shorten Survival Over Time

Prospective data regarding prognosis in ET are limited.1,2 In general, ET is a chronic disease that does not shorten life expectancy in the first decade following diagnosis; however, over longer periods of time, survival may be shortened.1 Median survival of ET is about 20 years.3

Prognostic variables that are associated with shortened survival in patients with ET include the following1:
  • Age ≥60 years
  • Occurrence of any major thrombosis at or after diagnosis
  • Diabetes mellitus
  • History of arterial thrombosis
  • Tobacco use
  • Leukocyte count of ≥15 × 109/L at diagnosis
  • Hypertension

ET Risk Is Based on Age, History of Thrombosis, and Cardiovascular (CV) Risk Factors

Patients with ET who have a history of thrombosis or who are 60 years of age or older are considered to be at high risk, whereas patients who are younger than age 60 years or who lack a history of thrombosis but have CV risk factors (eg, diabetes, hypertension, or tobacco use) are considered to be at intermediate risk.4 Patients who are younger than age 60 years or who lack a history of thrombosis, have no CV risk factors, and have a platelet count of <1,000 × 109/L are considered to be at low risk.4

Progression

In some patients, ET may transform to myelofibrosis.5 If such a transformation occurs, a patient is said to have developed post–ET myelofibrosis.5 ET transforms to secondary acute myelogenous leukemia in a small minority of patients.6

Risk Stratification in Essential Thrombocythemia
Risk category
Age >60 years or history of thrombosis
Cardiovascular risk factorsa
Low
No
No
Intermediate
No
Yes
High
Yes
 
Extreme thrombocytosis (platelet count >1,500 × 109/L) is a potential risk factor for bleeding in ET. Increasing leukocyte count and JAK2V617F mutation have been identified as novel risk factors for thrombosis, but confirmation in prospective studies is required.
aHypertension, hypercholesterolemia, diabetes, smoking.
References

1. Wolanskyj AP, Schwager SM, McClure RF, et al. Mayo Clin Proc. 2006;81:159-166. 2. Beer PA, Green AR. Hematology Am Soc Hematol Educ Program. 2009:621-628. 3. Barbui T, Barosi G, Birgegard G, et al. J Clin Oncol. 2011;29:761-770. 4. Finazzi G, Barbui T. Leukemia. 2008;22:1494-1502. 5. Verstovsek S. Clin Cancer Res. 2010;16:1988-1996. 6. Abdel-Wahab O, Manshouri T, Patel J, et al. Cancer Res. 2010;70:447-452.