The use of 32 phosphorus (32P) in the treatment of polycythemia vera

The treatment of polycythemia vera with 32phosphorus (32P) raises two problems: 1) what is its therapeutic efficacity? 2) Does the use of 32P increase the risk of acute leukemia? The large series of treated patients have shown the remarkable efficacy of 32P. This is particularly evident when comparing the recent series of patients treated with 32P with those of Videbaek whose patients were treated by phlebotomies only. Patients are treated one time with 3.7 x 10(6) mBq (0.1 mCi) of 33P per kg of body weight. Granulocytes and platelets are rapidly affected, whereas red cells show a response 3 months later due to their longer survival. Remission lasts from a few months to three years. If the result is not satisfactory, another dose can be given 3 months after the first one. Resistance to 32P may arise but may be reversible after a course of chemotherapy. The clear therapeutic effect of 32P renders it especially valuable for patients with a high vascular risk. Some authors have claimed that polycythemia vera evolves towards acute leukemia, but Modan's study has demonstrated that 32P is indeed responsible for the occurrence of acute leukemia; this has been largely confirmed by others. The dose to the bone marrow is not negligible and the leukemic incidence following the treatment is a factor which limits its indication. Trials were conducted to search for therapies with alkylating agents, such as Chlorambucil or Busulphan, which would be less leukemogenic. The Polycythemia Vera Study Group found that Chlorambucil was at least 2.3 fold more leukemogenic than 32P. The EORTC compared the leukemogenic effect of 32P with that of Busulphan.(ABSTRACT TRUNCATED AT 250 WORDS)