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

Objective: Describe our experience in treatment with Phosphorus-32 (P-32 ) 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 (32 ) P in our hospital from January 1985 to March 2017. Indications, response to treatment, as well as early and late complications have been analyzed.<br /> Results: Of the 17 patients treated with (32) P (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 2 or more doses due to inadequate hematological response and/or relapse. The total dose range of (32) P administered was 116-951 MBq (median: 236MBq). In 14 patients treated with P-32 , complete or partial response was achieved in hematimetry. In 11 patients, the response was complete, established as a platelet count < 400.000/mm(3) 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 P-32 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 one case of mild thrombocytopenia. No leukemic transformation was identified. Conclusions: In our experience, treatment with P-32 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.