During 5 years from September 1991 to September 1996, 93 patients (pts) with acute lymphoblastic leukemia (ALL): 45 girls and 48 boys of average age 5y 10m, have been treated in the Department of Childhood Oncology. They were treated with two protocols designated as ALL SR 0491 for standard risk (SR ALL) and ALL HR 0591 for high risk acute lymphoblastic leukemia (HR ALL). Sixty two patients and thirty one patients were treated for SR ALL and HR ALL respectively. All patients received induction therapy consisting of Vincristin, Prednison, L-asparaginase and Adriamycin for HR ALL respectively. During consolidation phase HDMTX, 6-MP, Cyclophosphamide and Ara-C and Vumon for HR ALL respectively were applied. Prevention of CNS infiltration included intrathecal MTX for SR ALL or triple drug/MTX, AraC, Hydrocortison/ with or without radiotherapy (RAT) for HR ALL. Duration of maintenance therapy consisting of 6-MP, MTX and reinductions was 24 and 30 months for SR ALL and HR ALL respectively.

Complete remission (CR) was achieved in 92 pts (99%), one patient died of Pseudomonas septicemia before remission was obtained. During CR one patient died because of toxicity of therapy. 22 pts (24%) relapsed: 10 pts in bone marrow, 8 pts in CNS, 2pts in bone marrow and CNS, 1 patient in bone marrow and testis, 1 patient had extramedulary relapse (bone). 9 pts (30%) relapsed in HR ALL group, 13 pts (21%) in SR ALL group. Overall survival at 5 years was 0,65: for SR ALL 0,61, for HR ALL 0,68. EFS at 5 y was 0,55, for SR ALL 0,68, for HR ALL 0,40.

Relatively high rate of CNS involvement (8 pts, 8,7%) despite of HDMTX treatment indicated the necessity for irradiation of the neuraxis to prevent in CNS leukemia mainly patients with HR ALL. Usage of RAT in dose 8-12 Gy(depending on age) since March 1996 was incorporated into HR ALL 0591 protocol.