phosphorus-radioisotopes and Preleukemia

Topics: Acute Disease; Adult; Antineoplastic Agents; Bloodletting; Cell Transformation, Neoplastic; Chlorambucil; Female; Humans; Leukemia; Male; Phosphorus Radioisotopes; Polycythemia Vera; Pregnancy; Preleukemia; Prognosis; Pruritus; Uric Acid

In polycythemia vera (PV), treatment with chlorambucil and radioactive phosphorus (p32) increases the risk of leukemic transformation from 1% to 13-14%. This risk has been estimated to be 1-5.9% with hydroxyurea (HU) therapy. When compared with historical controls, the risk with use of HU does not appear to be statistically significant. The leukemogenic risk of HU therapy in essential thrombocytosis (ET) and in myelofibrosis with myeloid metaplasia (MMM) is unknown. HU remains the main myelotoxic agent in the treatment of PV, ET, and MMM. We studied 64 patients with these three disorders, seen at our institution during 1993-1995. The patients were studied for their clinical characteristics at diagnosis, therapies received, and development of myelodysplasia or acute leukemia (MDS/AL). Forty-two had PV, 15 ET, and 6 MMM, and 1 had an unclassified myeloproliferative disorder. Of the 42 patients with PV, 18 were treated with phlebotomy alone, 16 with HU alone, 2 with p32, 2 with multiple myelotoxic agents, and 2 with interferon-alpha (IFN-alpha). Two patients from the phlebotomy-treated group, one from the HU-treated group, and 1 from the multiple myelotoxic agent-treated group developed MDS/AL. In the larger group, 11 received no treatment or aspirin alone, 18 were treated with phlebotomy alone, 25 with HU, 5 with multiple myelotoxic agents, 2 with p32, 2 with IFN-alpha, and 1 with melphalan. Study of the entire group of 64 patients showed that only one additional patient (total of 5 out of 64) developed MDS/AL. This patient had been treated with HU alone. Statistical analysis did not show any association between clinical characteristics at diagnosis, or HU therapy, and development of MDS/AL (P=0.5). Thus, our data provide no evidence suggestive of increased risk of transformation to MDS/AL with HU therapy in PV, ET, and MMM. Larger, prospective studies are needed to study this issue further.

Topics: Acute Disease; Anemia, Refractory, with Excess of Blasts; Busulfan; Cell Transformation, Neoplastic; Chlorambucil; Cohort Studies; Disease Progression; Drug Therapy, Combination; Enzyme Inhibitors; Female; Humans; Hydroxyurea; Incidence; Interferon-alpha; Leukemia; Leukemia, Radiation-Induced; Male; Melphalan; Middle Aged; Phlebotomy; Phosphorus Radioisotopes; Polycythemia Vera; Preleukemia; Primary Myelofibrosis; Retrospective Studies; Ribonucleotide Reductases; Risk; Thrombocythemia, Essential

In 1954 a then 31-yr-old male was found to have erythrocytosis. Over the ensuing decade he received 72 mCi32P. In 1964 his daughters were found to have erythrocytosis. Further investigation led to the discovery of hemoglobin Yakima, a variant with high oxygen affinity. He received no further therapy and was well until 1975, when he developed the preleukemic syndrome. Within 12 mo. he developed acute nonlymphocytic leukemia accompanied by fetal erythropoiesis. Because the inital discovery of this type of hemoglobinopathy came 27 yr after the introduction of 32P for use in the treatment of polycythemia vera, and because there are now known to be more than 39 different high-oxygen-affinity hemoglobins, we anticipate that more patients such as ours have been exposed to 32P. The exposed population should be cosely followed, since this will likely permit assessment of the risk of 32P-induced leukemia in a nonneoplastic condition.

Topics: Acute Disease; Adult; Erythropoiesis; Hemoglobins, Abnormal; Humans; Leukemia, Radiation-Induced; Male; Middle Aged; Phosphorus Radioisotopes; Polycythemia; Preleukemia; Time Factors