EARLY TOXICITY OF INTENSIFIED CONDITIONING WITH ETOPOSIDE COMBINED WITH TOTAL-BODY IRRADIATION CYCLOPHOSPHAMIDE OR BUSULFAN CYCLOPHOSPHAMIDE IN CHILDREN UNDERGOING AUTOLOGOUS OR ALLOGENEIC BONE-MARROW TRANSPLANTATION

In recent years, high dose chemotherapy followed by bone marrow rescue has been established as a common treatment of hematologic and solid t umor malignancies. Despite unequivocal Success, relapse after transpla nt remains a serious problem, being the main cause of treatment failur e. In an attempt to reduce relapse rates, we intensified the condition ing regimens consisting of busulfan/cyclophosphamide versus fractionat ed total body irradiation (f-TBI)/ cyclophosphamide by the addition of high dose etoposide. Toxicity profiles of 25 pediatric patients with hematologic malignancies undergoing intensified conditioning did not d iffer significantly between the two groups, except for a higher Incide nce of veno-occlusive disease in busulfan-treated patients (3 of 13 pa tients) compared with the TBI group (0 of 12 patients). We observed no transplant-related mortality in neither group. Regimen-associated mor bidity was moderate and reversible in all cases. Five patients died in each treatment arm, due to relapse of the underlying disease. We conc lude that Both regimens are feasible in marrow transplantation of pedi atric patients. Open randomized trials are needed to assess the effica cy of intensified conditioning in terms of disease-free survival.