[Clinical trial of protocol-AL851 for children with high-risk acute lymphoblastic leukemia. Kyushu Yamaguchi Children's Cancer Study Group (KYCCSG)].

Fifty five children diagnosed as having high-risk acute lymphoblastic leukemia (ALL) between 1985 and 1988 were treated with protocol AL851. The agents used in the protocol were as follows: induction therapy: vincristine (VCR), prednisolone, daunorubicin (DNR) and l-asparaginase, consolidation therapy: an intermediate-dose methotrexate (MTX), central nervous system (CNS) leukemia prophylaxis: intrathecal MTX and 24Gy cranial irradiation, reinduction therapy: VCR, adriamycin, dexamethasone and high dose cytarabine (AraC), maintenance therapy: 6-mercaptopurine, cyclophosphamide, MTX, DNR, VCR and AraC. Patients received chemotherapy for 3 years after achieving complete remission (CR). CR was obtained in 51 patients (92.7%). Twenty-four of them relapsed after achieving CR (bone marrow 16, CNS 3 and testis 5). At median follow-up of 79 (range 64-102) months, the estimated 8-year disease free survival rate was 49.1 +/- 6.7%. Four patients relapsed at bone marrow during the first 6 months of the treatment, indicating that more intensive combination chemotherapy should be included in earlier stage of the protocol. The high incidence of testicular relapse (14.3% in boys) suggests that high-dose MTX or AraC should be needed for improvement of the prognosis of high-risk ALL patients.