Clinical characteristics and treatment results of patients diagnosed with essential thrombocythemia, who applied to the Hematology Polyclinic of Karadeniz Technical University faculty of medicine between 2010-2020

Objective: In this study, evaluation of the demographic characteristics, laboratory values at the time of diagnosis, clinical symptoms, applied treatment methods and complications observed during follow-up of Essential Thrombocythemia (ET) patients is aimed. Materials and Methods: As a first step, 397 patients who were followed up with the diagnosis of ET in the Hematology Polyclinic of KTU (Karadeniz Technical University) Farabi Hospital between 2010 and 2020 have been determined. Then, the data of 176 patients who met the study criteria have been examined. By taking into consideration of patients' age, date of diagnosis, last seen, gender, spleen size, complete blood count values at the time of diagnosis, comorbidities, genetic analyzes Janus-type Tyrosine Kinase 2 (JAK-2), Calreticulin 2 (CALR), Myeloproliferative Leukemia Virus Oncogene (MPL), the bone marrow findings and treatments, the secondary complications occurred in the patients have been recorded with their dates, and the patients are evaluated retrospectively. Findings: The study is conducted with a group of 176 patients consists of 96 (54,5%) female and 80 (45,5%) male, with a median age of 64 (20-87). It has been observed that the most frequent symptoms on presentation are fatigue (44%), headache (20%), and paresthesia (16%). Besides, there is a history of hypertension in 42%, coronary artery disease in 19%, hyperlipidemia in 13%, diabetes in 12%, and obesity in 5% of the patients. Furthermore, the JAK2 gene mutation is positive in 70% of the patients. Of the JAK2 gene mutation-negative patients, 31.5% had CALR gene mutation and 9% MPL gene mutation is positive. At the time of diagnosis, clinical laboratory tests show that mean hemoglobin value is 13,95 (±1,94) g/dl, mean leukocyte value is 11,968 (±7,111)x109/l, mean platelet value is 945,789 (±366,593)x109/l, and mean LDH value is 339,8 (±175,34) u/l. During follow-up, developed complications are transformation in 12 (9,7%), thrombosis in 7 (5,7%), and hemorrhage in 4 (3,2%) patients. The median survival time in all cases is 112,46 months. It has observed that the mean survival time decreases in patients who are over 60 years of age with the high bone marrow fibrosis score, in the high-risk group according to the thrombosis risk score, and developed transformation in the follow-up. Also, when the patient groups consist of JAK2 gene mutation positive and negative are evaluated comparatively, it is found that the risk of thrombosis increases, hemoglobin and leukocyte levels are high, and platelet levels are low in JAK2 gene mutation positive patients. Moreover, it is observed that patients with positive CALR gene mutations have lower age at diagnosis, are mostly male, and are often in the low thrombosis risk group. The age at diagnosis is found to be higher in MPL gene mutation positive patients. On the other hand, when the patients were divided into two groups as 60 years old or younger, and older than 60 years, it has been observed that in patients over 60 years of age the history of thrombosis, the frequency of complications, leukocyte and LDH levels are higher whereas the hemoglobin level is lower. Additionally, the patients are separated as two groups according to the development of transformation in the follow-up and these groups are evaluated with their laboratory test results and clinical characteristics. No difference is monitored between the groups in terms of age at diagnosis, gender, JAK2, CALR and MPL positivity, bone marrow fibrosis score and thrombosis risk. Also, for the patients who developed transformation, the incidence of splenomegaly is found to be higher while the hemoglobin levels are lower at the time of diagnosis. Besides that, according to the thrombosis risk score, most of the patients who developed transformation are in the high-risk patient group. Results: In this study, the characteristics of patients who have essential thrombocythemia have been found to be compatible with the literature. At the time of diagnosis, the frequency of transformation has been observed to be higher in patients with anemia and splenomegaly. Also, for elderly patients, the presence of a history of thrombosis at the time of diagnosis and the risk of complications have been seen to be higher. Moreover, JAK2 gene mutation is decided to be an important risk factor for thrombosis. On the other hand, it has been observed that older age (>60 years), grade >1 bone marrow fibrosis, high thrombosis risk score and development of transformation have a negative effect on the mean survival. In conclusion, evaluation of the presence of splenomegaly at the time of diagnosis, detection of cardiovascular risk factors and gene mutation analyzes are very important in terms of prolonging life expectancy and determining treatment options in patients with ET. Keywords: Essential Thrombocythemia, ET, JAK2, thrombosis, transformation