CASE-CONTROL ANALYSIS OF ALLOGENEIC BONE-MARROW TRANSPLANTATION VERSUS MAINTENANCE CHEMOTHERAPY FOR RELAPSED ALL IN CHILDREN

In a retrospective study, the results of maintenance chemotherapy and allogeneic bone marrow transplantation (BMT) for children who reached a second complete remission (CR2) of their acute lymphoblastic leukemi a (ALL) were compared. Case-control analysis was performed comparing 2 5 allogeneic transplant patients (cases) with 97 patients treated with maintenance chemotherapy (controls), who were matched for site of rel apse, duration of CR1 and leukemia-free interval from onset of CR2. Un til the first relapse, the children were treated according to standard protocols. The majority of patients suffered from a bone marrow relap se, mostly occurring more than 24 months after the onset of CR1. Remis sion reinduction treatment was heterogeneous, Patients treated with al logeneic BMT received high-dose chemotherapy and total body irradiatio n prior to BMT. Maintenance chemotherapy in controls was given for app roximately 2 years. Following BMT, relapse rate was lower but the trea tment-related mortality was higher compared with maintenance chemother apy, resulting in leukemia-free survival rates at 4 years of 44% and 2 4%, respectively (not significant, NS). Case-control analysis of leuke mia-free survival showed a hazard ratio of 0.756 in favor of BMT compa red with chemotherapy (NS). If bone marrow relapses and central nervou s system relapses were analyzed separately, a tendency to better leuke mia-free survival was present after BMT compared with maintenance chem otherapy for patients with a relapse in the central nervous system, bu t for an isolated bone marrow relapse, no differences in leukemia-free survival were seen between the two groups of patients.