A population-based study of children with standard risk acute lymphoblastic leukemia in the five Nordic countries. A follow-up of 230 patients

Two hundred and thirty children with standard risk acute lymphoblastic leukemia (ALL) were diagnosed during a period of 3 years from July 1, 1981 to June 30, 1984 in the five Nordic countries. Criteria for standard risk ALL were age above 2.0 and below 10 years, WBC less than or equal to 20 x 10(9)/l, no evidence of CNS-involvement, mediastinal mass or T- or B-cell leukemia. The children were treated without prophylactic CNS irradiation, the majority (200 patients) according to two treatment programs. Follow-up of the entire group after a minimum of 30 months showed 64% of the children living in complete continuous remission with a probability of event-free survival of 0.60. The treatment results are not entirely satisfactory and intensification of therapy is required. A subgroup of patients with WBC between 10 and 20 x 10(9)/l and with adverse prognosis was identified, justifying a change of the present criteria for risk grouping.