Long-term follow-up of Dutch Childhood Leukemia Study Group (DCLSG) protocols for children with acute lymphoblastic leukemia, 1984-1991

Here we report the long-term results of the DCLSG protocols ALL-6 and -7 wi th special emphasis on the incidence of CNS relapse after treatment without cranial irradiation. In DCLSG protocol ALL-6 (1984-1988), designed for pat ients with ALL non-high risk (ALL-NHR) (WBC <50 x 10(9)/l, no mediastinal m ass, no B cell phenotype and no CNS involvement at diagnosis, comprising 71 % of all ALL patients), CNS prophylaxis consisted of a combination of three methods of chemotherapeutic CNS prophylaxis (the use of dexamethasone duri ng induction and maintenance therapy, i.v. medium dose methotrexate and pro longed administration of intrathecal triple therapy). Total duration of tre atment: 116 weeks. 190 patients were enrolled in the study. At 10 years, th e EFS rate for all patients is 81.5 +/- 2.8%, the survival rate 84.8 +/- 2. 7%, and the cumulative incidence of isolated CNS relapse 1.1 +/- 0.8%. The 10-year survival rate for the 139/190 (73.1%) patients with standard risk n on-T lineage ALL according to the NCI risk criteria is 80.5 +/- 3.4%. DCLSG protocol-7 was identical to the intensive ALL-BFM-86 protocol, but cranial irradiation was restricted to patients with initial CNS involvement, Patie nts were stratified into three risk groups (SRG, RG and EG). Treatment dura tion was 18 months. 218 patients were enrolled in the study. At 10 years, t he EFS rate for all patients is 63.4 +/- 3.3%, the survival rate 76.4 +/- 3 .0%, the 5-year cumulative incidence of isolated CNS relapse 5.7 +/- 1.8%. The EFS rate at In years of the 127/218 (58.3%) patients with standard risk non-T-lineage ALL according to the NCI risk criteria was 67.9 +/- 4.3%, wh ich is not significantly different from the results achieved in this catego ry of patients with the moderately intensive treatment according to protoco l ALL-6 (logrank P= 0.17). These DCLSG studies indicate that omission of cr anial irradiation does not jeopardize the overall good results.