THE ROLE OF LOW-DOSE CHEMOTHERAPY IN MYELODYSPLASTIC SYNDROMES

Aggressive chemotherapy of myelodysplastic syndromes is rarely feasible because these disorders predominantly occur in elderly patients who often have concurrent illnesses. Alternative treatment modalities must therefore be evaluated. This review summarizes the results that have been obtained with low-dose chemotherapy, especially with low-dose cytosine arabinoside (Ara-C). Overall response rates to treatment with low-dose Ara-C are about 40%, with some 20% of patients achieving a complete remission. Transition of MDS to AML does not reduce the probability of response. The therapeutic outcome cannot be reliably predicted by clinical or experimental parameters. Hematological toxicity is substantial, with approximately 10-25% treatment-related deaths. Duration of response is short and rarely exceeds one year. In terms of overall survival, low dose Ara-C does not appear to be superior to supportive care only. Other cytotoxic agents have not been studied in detail, but data available do not suggest an appreciable advantage over Ara-C. Before denying low-dose chemotherapy a helpful role in MDS, randomized studies should concentrate on those patients who can be expected to derive the greatest benefit. Because of their short survival, patients with RAEBt or those transformed to overt leukemia are such candidates.