Hematology Department, Hospital Clinic, University of Barcelona, Barcelona, Spain.
Hematology Am Soc Hematol Educ Program. 2011;2011:215-21. doi: 10.1182/asheducation-2011.1.215.
Essential thrombocythemia (ET) is a Philadelphia chromosome (Ph)-negative myeloproliferative neoplasm (MPN) characterized by thrombocytosis and megakaryocytic hyperplasia of the bone marrow, with presence of the JAK2 V617F mutation in 50%-60% of patients. ET evolves to myelofibrosis in a minority of cases, whereas transformation to acute leukemia is rare and increases in association with the use of certain therapies. Survival of ET patients does not substantially differ from that of the general population. However, important morbidity is derived from vascular complications, including thrombosis, microvascular disturbances, and bleeding. Because of this, treatment of ET must be aimed at preventing thrombosis and bleeding without increasing the risk of transformation of the disease. Patients are considered at high risk of thrombosis if they are older than 60 years or have a previous history of thrombosis and at high risk of bleeding if platelet counts are > 1500 × 10(9)/L. Patients with low-risk ET are usually managed with low-dose aspirin, whereas treatment of high-risk ET is based on the use of cytoreductive therapy, with hydroxyurea as the drug of choice and IFN-α being reserved for young patients or pregnant women. For patients resistant or intolerant to hydroxyurea, anagrelide is recommended as second-line therapy. Strict control of coexistent cardiovascular risk factors is mandatory for all patients. The role in ET therapy of new drugs such as pegylated IFN or the JAK2 inhibitors is currently under investigation.
原发性骨髓纤维化（ET）是一种费城染色体（Ph）阴性的骨髓增殖性肿瘤（MPN），其特征为血小板增多和骨髓巨核细胞增生，约 50%-60%的患者存在 JAK2 V617F 突变。在少数情况下，ET 会进展为骨髓纤维化，而转化为急性白血病则较为罕见，且与某些治疗方法的使用相关。ET 患者的生存与一般人群无显著差异。然而，重要的发病率源于血管并发症，包括血栓形成、微血管紊乱和出血。因此，ET 的治疗必须旨在预防血栓形成和出血，同时不增加疾病转化的风险。如果患者年龄大于 60 岁或有既往血栓形成史，则被认为存在高血栓风险；如果血小板计数>1500×10(9)/L，则存在高出血风险。低危 ET 患者通常采用低剂量阿司匹林治疗，而高危 ET 的治疗则基于细胞减灭治疗，羟基脲是首选药物，IFN-α 则保留给年轻患者或孕妇。对于不耐受或不能耐受羟基脲的患者，可推荐使用安纳格雷尔作为二线治疗。所有患者都必须严格控制并存的心血管危险因素。新型药物，如聚乙二醇化 IFN 或 JAK2 抑制剂在 ET 治疗中的作用目前正在研究中。
