INTENSIFIED TREATMENT OF ACUTE CHILDHOOD LYMPHOBLASTIC-LEUKEMIA 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 countr ies (Denmark, Finland, Iceland, Norway and Sweden), 2648 children belo w 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 regio nal or national protocols to common Nordic treatment protocols for all risk groups was completed in 1992 through a successive intensificatio n of therapy, based on multidrug chemotherapy including pulses of meth otrexate in high doses and avoidance of cranial irradiation in most ch ildren. For children with non-B-cell ALL (n = 2602), the event-free su rvival (p-EFS) increased from 0.53 +/- 0.02 (diagnosed 7/81-6/86) to 0 .67 +/- 0.02 (7/86-12/91) to 0.78 +/- 0.02 (1/92-12/96). The correspon ding p-EFS values at 5 y were 0.57, 0.70 and 0.78, respectively. The m ain 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 0.8 5 for the three periods. In high-risk patients, progress has been mode rate, especially in children with high white blood cell values at diag nosis. During the last 5-y period, only 10% of the patients received c ranial irradiation in first remission while 90% of the patients receiv ed high doses of cytostatic infusions (methotrexate isolated or combin ed with cytarabinoside) and multiple intrathecal injections of methotr exate as CNS-adjusted treatment without any indication of an increased CNS relapse rate.