Management of polycythaemia vera, essential thrombocythaemia and myelofibrosis with hydroxyurea.

A total of 59 symptomatic patients with myeloproliferative disorders (polycythaemia vera 24 pats., essential thrombocythaemia 25 pats., myelofibrosis 10 pats.) and elevated platelet counts were studied during 1653 months of continuous treatment with hydroxyurea. Reduction of the platelet level to less than 500 x 10(9)/l was achieved within 8 weeks in 86% of polycythaemia pats., 80% of thrombocythaemia pats., 60% of myelofibrosis pats. Control of disease-related symptoms was achieved within 1 year in 78% of the patients. There was no instance of severe bone marrow toxicity. Side-effects of hydroxyurea were modest. Survival was excellent, with 86% probability of survival after 5 yr of therapy. We consider hydroxyurea a first-choice alternative in the treatment of patients with polycythaemia vera, essential thrombocythaemia and mylofibrosis with thrombocytosis.