A review published in the American Journal of Hematology details current aspects of diagnosis, risk stratification, and management of essential thrombocythemia (ET). The review was written by Ayalew Tefferi, MD, of Mayo Clinic in Rochester, Minnesota; Alessandro Maria Vannucchi, MD, of the University of Florence in Florence, Italy; and Tiziano Barbui, MD, of Papa Giovanni XXIII Hospital in Bergamo, Italy.
Regarding ET diagnosis, Tefferi and colleagues highlighted criteria from the International Consensus Classification. This system involves multiple criteria for ET diagnosis, such as thrombocytosis (with a platelet count ≥450×109/L), exclusion of other myeloid neoplasms, and other features, such as possible mutation of JAK2, CALR, or MPL. However, the authors noted, up to 20% of patients having ET might be negative for mutations in all 3 of these genes.
According to data from the Surveillance, Epidemiology, and End Results Registry in the US, the 5-year survival rate among 8768 patients with ET was 88.7%. The median survival time for this population was 12.1 years.
Among risk factors related to survival with ET, the authors considered age to be most important. Additional risk factors identified for survival vary by the risk model being used. The triple A survival risk model, for example, includes absolute neutrophil count and absolute lymphocyte count, in addition to age, and stratifies patients into 4 risk groups with median survival times ranging from 8 years in the high-risk group to 47 years in the low-risk group. The authors emphasized age, presence of a thrombosis history, and presence of JAK2 mutation as risk factors for thrombosis with ET.
In describing their treatment approach to ET, the authors indicated they began with consideration of thrombosis risk stratification, with some treatment options within thrombosis risk groups based on cardiovascular risk.