The clinical course of 29 patients with idiopathic refractory sideroblastic anemia studied by us was reviewed. Four patients developed acute leukemia. We were able to find 2'7 out of 268 cases of idiopathic refractory sideroblastic anemia reported in the literature which terminated in acute leukemia. Nine of these were well described. The overall incidence of acute leukemia is 10%. In an attempt to identify the risk factors for the development of acute leukemia, the clinical and laboratory features of this group of thirteen well-described cases which terminated in acute leukemia were compared to the remaining 25 of our cases which did not undergo leukemic transformation. The patients who died of acute leukemia tended to have a more severe anemia, a lower reticulocyte count, and increased transfusion requirement, and thrombocytopenia. Thrombocytosis appears to be a relatively good prognostic sign.
Cancer 44:724-731, 1979.
ONTROVERSY EXISTS AS TO whether idio-C pathic refractory sideroblastic anemia (IRSA) frequently terminates in acute leukemia or remains a chronic refractory anemia without leukemia transformation and a long survival. Dameshek suggested that IRSA is an early phase of erythremic myelosis or the Di Guglielmo syndromeI7 and that if the patients were followed long enough, acute leukemia would be the terminal event in "approximately 50 percent" of cases.18 On the other hand, in a previous report we reviewed the clinical and laboratory findings in 44 patients with IRSA who were well described in the literature and 17 studied at our own i n s t i t u t i ~n . ~~ We concluded that the course of most patients with IRSA was rather benign, with a median survival of 10 years. The incidence of acute myeloblastic leukemia in patients with IRSA was approximately 7%. The purpose of this report is to update our experience with this disease entity, adding 12 more cases studied by us. In addition, a careful review of the literature has been undertaken in an attempt to determine the incidence and