Essential thrombocythemia is a chronic disease common in people over age 50 and slightly more common in women. Young people can develop it as well. It is characterised by the overproduction of platelets by megakaryocytes in the bone marrow. Essential thrombocythemia is an uncommon disorder where the body produces too many blood platelets. This condition may cause to feel fatigued, lightheaded and to experience headaches and vision changes. It also increases the risk of blood clots.
The greatest health risk in patients with ET is an increased risk of developing blood clots. Blood clots can be in the deep vessels of the legs or lungs; ET patients are also more likely to experience strokes and heart attacks. ET patients can develop clots elsewhere, including within the abdomen, an otherwise rare site for clots to form. The risk of clotting increases with age, and disease-associated risks may be quite different for children than for adults, with children generally being at low risk for clots and other problems related to ET.
We conducted the first nationwide survey to clarify the clinical features, treatment methods, and prognoses for polycythemia vera (PV) and essential thrombocythemia (ET). A 1-page questionnaire was mailed to members of the Japanese Elderly Leukemia and Lymphoma Study Group (JELLSG). Surveys on 647 patients (PV, 266 patients; ET, 381 patients) were returned and analyzed. Thrombotic events at diagnosis and during follow-up occurred at rates of 15.4% and 8.5%, respectively, in PV cases and 17.6% and 8.7% in ET cases. Splenomegaly was observed in only 28.8% of PV patients and 10.8% of ET patients. The leukocyte alkaline phosphatase score was elevated in only 46.2% of PV patients. The incidences of abnormal karyotypes were less than 10% in both PV and ET cases. The rates of transformation to myelofibrosis were 2.6% in both PV and ET cases, and acute leukemia was noted in 1.1% of PV patients and 2.9% of ET patients. Prognostic factors were thrombotic history for PV and thrombotic history and age (>or=60 years) for ET. The present study clearly demonstrated clinical differences between Japanese and Western patients for PV and ET. Concerning the treatment of PV and ET, the study revealed considerable variation among Japanese hematologists. These results suggest the necessity of developing treatment guidelines according to risk stratification that are suitable for Japanese PV and ET patients.