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Bone marrow transplantation versus chemotherapy for maintenance of second remission of childhood acute lymphoblastic leukemia: a study of the Children's Cancer Group (CCG-1884).

BACKGROUND
Maintenance of second remission of childhood acute lymphoblastic leukemia (ALL) with intensive chemotherapy is often unsuccessful. The major cause of treatment failure is relapse.


MATERIALS AND METHODS
Of 96 children with ALL who relapsed in the marrow while on or within 1 year of completing initial therapy, 62 achieved a second remission. Nineteen patients underwent bone marrow transplantation in second remission, 11 from a human leukocyte antigen (HLA)-matched related donor, seven using autologous marrow, and one from a matched unrelated donor. The event-free survival (EFS) of transplanted patients was compared to that of patients treated with intensive chemotherapy using high-dose cytarabine, vincristine, escalating dose methotrexate, L-asparaginase, and an anthracycline (daunorubicin or idarubicin). Only those patients treated with chemotherapy who survived in second remission up to the mean time that patients were transplanted (135 days) were included in the control group (33 of 43 patients who achieved second remission).


RESULTS
The actuarial 2-year event-free survival of transplanted patients is 37+/-22% (95% C.I.) compared to 18+/-13% for chemotherapy-treated patients (P=0.017). EFS for allo-transplant recipients was similar to that for auto-transplant recipients. Duration of initial remission was a strong predictor of the outcome of retrieval therapy. Patients whose initial remission was greater than 3 years had better EFS after achieving second remission (five of 11 still in remission, compared to four of 41 patients whose initial remission was less than 3 years). Adjustment in the multivariate analysis for duration of initial remission did not diminish the benefit of transplant over chemotherapy.


CONCLUSIONS
While there remains considerable possibility for further improvement in EFS after achieving second remission of childhood ALL, bone marrow transplant is superior to chemotherapy in maintaining second remission.