[Effect of low-dose Ara-C in the treatment of refractory, atypical leukemia and myelodysplastic syndrome].

This study was designed to evaluate the effect of low-dose Ara-C in the treatment of refractory, atypical leukemia and myelodysplastic syndrome (MDS). The subjects were 33 patients (19 acute myelocytic leukemia (AML), 9 MDS, 3 atypical leukemia and 2 unclassified leukemia). The age range was 19 to 84 years with a mean age of 51.5 years. We administered low-dose Ara-C (5-10 mg/m2/12 h s.c. or i.v.) for 13 to 35 days with a mean of 16.7 days. Complete remission and partial remission were obtained in 8 of 31 (25.8%) and in 9 of 31 (29.0%) respectively. A high response rate was found in M2 types showing a tendency for mature and refractory anemia with excess blasts in MDS according to the FAB classification. In our cases, severe pancytopenia in peripheral blood as a result of Ara-C was observed before normal hematopoiesis recurred. From the above results, the mechanism of low-dose Ara-C may induce remission by a cytotoxic rather than a differentiation effect. This treatment can be offered to patients with refractory, atypical leukemia and MDS with limited toxicity.