Porty-one patients with chronic myelocytic leukemia were treated with busulfan, 0.1 mg/kg/day, or cyclophosphamide, 2.0 mg/kg/day, orally for 8-12 weeks in a double-blind study. In the busulfan-treated group, there were 5 complete remissions, 10 partial remissions, 4 slight remissions, and no remission in one patient. In the cyclophosphamide-treated group, there were no complete remissions, 10 partial remissions, 4 slight remissions, and no remission in 7 patients. The difference in the number of patients achieving complete remissions is statistically significant (P = 0.02). Furthermore, there was marked difference in the ease of maintenance of remission in the two groups. Seven patients treated with cyclophosphamide relapsed during the period of study; no patient relapsed in the busulfan group (P = 0.005).
HE CLINICAL USE OF BUSULFAN WAS FIRST
T reported by Haddow and Tirnmis,s and Galton2 in 1953. Because of its effectiveness, ease of administration, and relatively low toxicity, busulfan was quickly accepted by most hematologists as the drug of choice in the treatment of chronic myelocytic leukemia. Since 1957, cyclophosphamide has been widely used in the treatment of malignant lymphomas, acute leukemias, and other solid tumors. Gross et al.3 reported in 1958 that cyclophosphamide was also effective in CML. Subsequent studies by Haar: Solomon,l2 and Frommeyerl confirmed the efficacy of cyclophosphamide in CML. In general, it was felt that cyclophosphamide was inferior to busulfan.