Response, complications and risk of leukemic transformation of phosphorus-32p treatment in philadelphia-negative chronic myeloproliferative syndromes.

Objective: Describe our experience in treatment with Phosphorus-32P for refractory Philadelphia negative chronic myeloproliferative syndromes or with side effects to the usual treatment, its complications and risk of leukemic transformation.

Material and methods: Retrospective descriptive study including 17 patients with a diagnosis of Philadelphia-negative chronic myeloproliferative syndrome treated with Phosphorus-32P in our hospital from January 1985 to March 2017. Indications, response to treatment, as well as early and late complications have been analyzed.

Results: Of the 17 patients treated with 32P (11 men, 6 women; mean age 79,8 years), 6 patients had Polycythemia Vera and 11 Essential Thrombocytosis. A single dose was administered in 9 of the subjects, the rest required two or more doses due to inadequate hematological response and/or relapse. The total dose range of Phosphorus-32P administered was 116-951 MBq (median: 236 MBq). In 14 patients treated with Phosphorus-32P, complete or partial response was achieved in hematimetry. In 11 patients, the response was complete, established as a platelet count <400.000/mm³ in those diagnosed with Essential Thrombocythemia and a hematocrit <45% in cases of Polycythemia Vera. The median follow-up of patients from the date of the first treatment of Phosphorus-32P until study completion or death was 37 months (range: 5-230 months). Regarding early complications, 2 cases of anemia requiring blood transfusion were observed, and 1 case of mild thrombocytopenia. No leukemic transformation was identified.

Conclusions: In our experience, treatment with Phosphorus-32P has been a useful therapeutic option in Philadelphia-negative chronic myeloproliferative syndromes in elderly patients who showed poor tolerance and/or resistance to first-line treatment. No leukemic transformation was identified.