The Management of Polycythaemia Vera.

Thrombo-embolic complications are the commonest cause of morbidity and mortality in untreated PV. Control of the PCV (<0.45) and platelet count (<400 x 10(9)/I) minimizes the risk of these complications. In addition, suppression of megakaryocytic proliferation delays myelofibrotic transformation, which is probably the 'natural' long-term outcome of PV. A small percentage of patients transform to acute leukaemia, particularly after myelofibrotic transformation. Leukaemic transformation is enhanced with some forms of myelosuppression, notably high accumulated doses of chlorambucil and (32)P. Venesection should be used initially to reduce the PCV and subsequently as required. The choice of myelosuppressive agent depend on the patients age. Older patients can be managed with (32)P, low-dose busulphan or pipobroman. Hydroxyurea has a role in the management of patients at all ages, although it possibly enhances the leukaemogenic risk. Therefore, agents such as interferon-α or anagrelide should be considered in younger patients.