Therapy-related leukemia or myelodysplasia (t-leuk/MDS) is a serious problem that is increasing in frequency. We studied the clinical characteristics of 96 patients (pts) with a mean age of 48 years, and analyzed the molecular parameters that could predispose to t-leuk/MDS. Hematological malignancies were the most common primary (53%), followed by breast and ovarian cancer (30% combined). The mean latency until the development of t-AML was 45.5 months. Median survival was 10 months. Cytogenetics was abnormal in 89% of pts. FLT3 internal tandem duplications were found in six of 41 (14.6%) pts, of whom four had an abnormal karyotype. Analysis of drug metabolism and disposition genes showed a protective effect of the CYP3A4 1 n B genotype against the development of t-leuk/ MDS, whereas the CC genotype of MDR1 C3435T and the NAD(P)H:quinone oxidoreductase1 codon 187 polymorphism were both noncontributory. Microsatellite instability (MSI) analysis using fluoresceinated PCR with ABI sequence analyzer demonstrated that 41% of pts had high levels of MSI in four or more of 10 microsatellite loci. Immunohistochemistry demonstrated reduced expression of MSH2 and MLH1 in 6/10 pts with MSI as compared to 0/5 of pts without MSI. In conclusion, genetic predisposition as well as epigenetic events contribute to the etiology of t-AML/MDS.

In this retrospective study, we aim to analyze the characteristics, treatments, and overall survival of all patients presenting with isolated myeloid sarcoma (MS) or MS with concomitant acute myeloid leukemia (AML) compared with all patients with AML, treated during the same period. We identified patients with AML with or without MS at diagnosis, presenting to our medical center between the years 1990 and 2005. There was no statistically significant difference between the groups regarding gender, age, cytogenetic risk groups, rate of complete remission, number of cycles of chemotherapy needed to achieve complete remission, and rate of first relapse. The time to death in the MS group was not significantly different (p = 0.60) from the AML group, and radiotherapy did not affect the median time to death. Transplantation prolonged survival in both groups (p = 0.018 and p < 0.0001, respectively). Patients with MS at diagnosis might benefit from upfront aggressive treatment with hematopoietic stem cell transplantation.