Therapy-related leukemia and myelodysplastic syndrome: a large-scale Japanese study of clinical and cytogenetic features as well as prognostic factors.

It is known that alkylating agents and topoisomerase II inhibitors can cause distinct forms of therapy-related leukemia and myelodysplastic syndrome (TRL/MDS). Although several reports have been made on each of these agents separately, no study has yet been conducted to evaluate the effect of these two types of agents in the same population. In a nationwide, large-scale population study, the clinical and cytogenetic features as well as the prognostic factors in 256 patients with TRL/MDS were assessed. Median age was 61 years, and the median period of latency from primary malignancies was 47.9 months. The latency period was significantly shorter in patients undergoing chemotherapy, especially that of topoisomerase II inhibitors, for primary cancer. The morphological diagnosis of TRL/MDS was acute myeloid leukemia in 59% and MDS in 41% of patients. Chromosome abnormalities that frequently involved chromosomes 5, 7 or 11 were documented in 77% of the 189 patients examined. MLL gene rearrangements were detected in 11 of 58 subjects and were correlated with a borderline significance (P = 0.072) with topoisomerase II inhibitor administration. Overall median survival was only 9.7 months. Survival was similar in cases with or without MLL gene rearrangement. Multivariate analysis identified chromosome 5 abnormalities, hypoproteinemia, poor therapy outcomes for primary cancer, C-reactive protein, and thrombocytopenia as being significantly poor prognostic factors (P < 0.05). This large-population study provided a comprehensive update of TRL/MDS status in Japan, identified significant prognostic factors, and enabled the clinical significance of MLL gene rearrangement to be assessed.