Background: Few data are available on therapy-related myelodysplastic syndromes and acute myeloid leukemia developing after radioiodine treatment.
Design and methods: We retrospectively analyzed 39 patients with myeloid neoplasms following radioiodine treatment, whose data were reported to the Duesseldorf Myelodysplastic Syndromes Register (8 of 3814 patients) and five other German Myelodysplastic Syndromes centers (n=31) between 1982 and 2011. These data were compared with those from 165 patients from our Myelodysplastic Syndromes Register with therapy-related myeloid neoplasms following chemotherapy (n=90), radiation (n=30), or radiochemotherapy (n=45).
Results: With a median latency of 79 months, 18 patients developed therapy-related acute myeloid leukemia and 21 presented with therapy-related myelodysplastic syndromes (8 refractory anemia with excess blasts I/II, 6 refractory anemia with multilineage dysplasia, 3 myelodysplastic syndromes with del(5q), 1 refractory anemia, 1 refractory anemia with ring sideroblasts, 1 chronic myelomonocytic leukemia II, 1 myelodysplastic/myeloproliferative neoplasm unclassifiable). Risk assessment according to the International Prognostic Scoring System was low-risk in 23%, intermediate-1 in 29%, intermediate-2 in 35%, and high-risk in 13%. Karyotype was abnormal in 68%, with chromosomes 7 (30%), 5 (26%), 8 (26%) and 3 (17%) being most frequently affected. No differences in the distribution of gender, World Health Organization subtype, acute myeloid leukemia progression, International Prognostic Scoring System score, and cytogenetic risk were observed between patients with therapy-related myeloid neoplasms following radioiodine or other treatment modalities. Of 17 patients who received induction chemotherapy, 71% were refractory to this treatment or died from treatment-related toxicity. The median overall survival in the entire group was 21.7 months (95%-CI 10.5-33 months) and did not differ significantly in comparison to the survival of patients with therapy-related myeloid neoplasms following other cytotoxic treatments. Patients with therapy-related acute myeloid leukemia had significantly inferior overall survival (12.4 versus 28.7 months, P=0.002).
Conclusions: Patients developing a therapy-related myeloid neoplasm after radioiodine treatment usually present with biological characteristics similar to those seen in patients with therapy-related myeloid neoplasms following other cytotoxic treatment modalities, associated with a low response rate to induction chemotherapy and poor prognosis.