Cytogenetic abnormalities in essential thrombocythemia: prevalence and prognostic significance

OBJECTIVES: In the current study we describe cytogenetic findings as well as clinical correlates and long-term prognostic relevance of abnormal cytogenetics at the time of diagnosis of essential thrombocythemia (ET). PATIENTS AND METHODS: The study cohort consisted of a consecutive group of patients with ET who fulfilled the World Health Organization diagnostic criteria, and in whom cytogenetic analysis was performed at diagnosis. RESULTS: A total of 402 patients were studied (median age, 56 yrs; median follow-up 70 months). The prevalence of abnormal cytogenetics at diagnosis was 7% (28 of 402). The most common cytogenetic anomalies were trisomy 9 (four patients), abnormal chromosome 1 (three patients) and trisomy 8 (two patients). Parameters at diagnosis that were significantly associated with abnormal cytogenetics included palpable splenomegaly (P = 0.03), current tobacco use (P = 0.04); venous thrombosis (P = 0.02), and anemia with a hemoglobin of <10 g/dL (P = 0.02); but did not include JAK2V617F mutation status, or advanced age. During follow up, patients with abnormal cytogenetics did not have shorter survival, or increased transformation to acute leukemia or myelofibrosis. CONCLUSION: Cytogenetic anomalies at diagnosis are relatively uncommon in ET, and do not predict evolution into more aggressive myeloid disorders, or inferior survival.