Intensified treatment of acute childhood lymphoblastic leukaemia has improved prognosis, especially in non‐high‐risk patients: the Nordic experience of 2648 patients diagnosed between 1981 and 1996

In a multinational, population-based study from the five Nordic countries (Denmark, Finland, Iceland, Norway and Sweden), 2648 children below 15 y of age were diagnosed with acute lymphoblastic leukaemia (ALL) in the years 1981-1996. The annual incidence was 3.9/100 000 children and was stable throughout the study period. The development from regional or national protocols to common Nordic treatment protocols for all risk groups was completed in 1992 through a successive intensification of therapy, based on multidrug chemotherapy including pulses of methotrexate in high doses and avoidance of cranial irradiation in most children. For children with non-B-cell ALL (n o 2602), the event-free survival (p-EFS) increased from 0.53 6 0.02 (diagnosed 7/81-6/86) to 0.67 6 0.02 (7/86-12/91) to 0.78 6 0.02 (1/92-12/96). The corresponding p-EFS values at 5 y were 0.57, 0.70 and 0.78, respectively. The main improvements were seen in the group of children with non-high risk leukaemia, with 5-y p-EFS values increasing from 0.60 to 0.76 and 0.85 for the three periods. In high-risk patients, progress has been moderate, especially in children with high white blood cell values at diagnosis. During the last 5-y period, only 10% of the patients received cranial irradiation in first remission while 90% of the patients received high doses of cytostatic infusions (methotrexate isolated or combined with cytarabinoside) and multiple intrathecal injections of methotrexate as CNS-adjusted treatment without any indication of an increased CNS relapse rate. ' Childhood acute lymphoblastic leukaemia, incidence, prognosis in childhood acute lymphoblastic leukaemia, prognostic factors, treatment results