Maintenance therapy of 32P-induced remission in polycythemia vera. A clinical trial of chlorambucil and hydroxy-urea in 109 cases.

In 109 patients with polycythemia vera, previously treated by 32P without maintenance therapy, a trial was carried out to determine the best way to reduce the number of injections needed. Chlorambucil and hydroxy-urea have been used to lengthnen the remission. Both of them are well tolerated and compatible with follow-up at reasonable time intervals. Chlorambucil maintenance increases the mean duration of remission by 12 months, the best results being observed when the drug was used continuously, instead of an intermittent (3 consecutive days every fortnight) schedule. Hydroxy-urea does not produce statistically demonstrable advantage whatever it is given, continuously or intermittently. Our study shows that, if a long-term cooperative study of the possible advantage of maintenance therapy in P.V. was undertaken in the future, low-dosage maintenance by chlorambucil could be the treatment of choice.