Polycythaemia vera and essential thrombocythaemia in the elderly.

Essential thrombocythaemia (ET) and polycythaemia vera (PV) both belong to the group of chronic myeloproliferative disorders which originate at the haematopoietic stem cell level with retention of their cellular differentiating capacity. The clinical course of both ET and PV is frequently complicated by potentially life-threatening thrombotic events and a variable rate of progression to myelofibrosis and leukaemic conversion (the latter in particular for PV). However, due to the relative paucity of randomised clinical trials in both ET and PV, a sound scientific basis for making therapeutic decisions is lacking. The management of patients with ET or PV should probably be addressed by categorising patient populations into groups with either a 'low risk' or 'high risk' for thrombosis after taking into account the risk factors for thrombosis (advanced age and/or previous thrombotic complications, and increased haematocrit). The goal of treatment in PV and ET is, however, not only to reduce the risk of thrombosis but also to reduce the risk of transformation into acute myeloid leukaemia or myelofibrosis. In this review we will discuss in detail the diagnosis, clinical manifestations and epidemiology, rationale for treatment, and the various treatment options for ET and PV with an emphasis on treatment efficacy and therapy-related leukaemic risk.