Despite myelosuppression, polycythemic (PV) patients greater than 65 years of age have a high risk of vascular complications, and the leukemic risk exceeds 15% after 12 years, Is the addition of low-dose maintenance treatment with hydroxyurea (HU) after radiophosphorus (P-32) myelosuppression able to decrease these complications? Since the end of 1979, 461 patients were randomized to receive (or not) low-dose HU (5 to 10 mg/kg/d), after the first P-32-induced remission, and were observed until death or June 1996, Maintenance treatment very significantly prolonged the duration of P-32-induced remissions and reduced the annual mean dose received to one-third. However, despite this maintenance, 25% of the patients had an excessive platelet count and the rate of serious vascular complications was not decreased, except in the most severe cases with shortterm relapse of polycythemia. Furthermore, the leukemia rate was significantly increased beyond 8 years and a significant excess of carcinomas was also observed, The continuous use of HU did not decrease the risk of progression to myelofibrosis (incidence of 20% after 15 years). Life expectancy was shorter (a median of 9.3 years v10.9 years with P-32 alone), except in the most severe cases (initial P-32-induced remission lasting <2 years) in which maintenance treatment moderately prolonged the survival by reducing the vascular risk. In most cases of PV, in which the duration of the first P-32-induced remission exceeded 2 years, the introduction of HU maintenance did not reduce the vascular risk, Although it considerably decreased the mean dose of P-32 received, HU maintenance therapy significantly increased the leukemia and cancer risks and reduced the mean life expectancy by 15%, However, in cases with more rapid recurrence, the introduction of maintenance treatment reduced the vascular risks and moderately prolonged survival. The use of HU as a maintenance therapy is therefore only justified in this situation. (C) 1997 by The American Society of Hematology.
