CLINICAL AND PROGNOSTIC-SIGNIFICANCE OF CHROMOSOMAL-ABNORMALITIES IN CHILDHOOD ACUTE MYELOID-LEUKEMIA DE-NOVO

We report on the chromosomal pattern of 120 patients with childhood AM L de novo. One hundred and fifteen patients (96%) had adequate samples for analysis; 98 (85%) of these showed clonal karyotypic abnormalitie s. They were classified into cytogenetic subgroups which were closely correlated with FAB subtypes: t(8;21) and M2 (n = 9); t(15;17) and M3 (n = 12); inv(16) and M4Eo (n = 9); t(9;11) and M5a (n = 10); t(11q23) other than t(9;11) and M4-M5 (n=11); and t(1;22) and M7 (n = 4). In p atients with -7/del(7q)(n = 6), leukemia was preceded by MDS in half o f the cases, although they had diverse FAB subtypes. Thirty-seven pati ents had miscellaneous abnormalities. Despite a high CR rate, patients with t(8;21) had a very poor survival: only one child was event-free at 3 years from diagnosis. One third of patients with t(15;17) died du ring induction. Those eight who achieved CR fared well: only two relap sed, and six were with event-free survivors. Patients with inv(16) had a high remission rate and a long survival: five children were in CR 2 0 to 136 months. Both groups with t(9;11) and t(11q23) had a high remi ssion rate: however, outcome was superior for the t(9;11) group when c ompared to either the t(11q23) group (EFS at 3 years +/- SE, 56+ +/- 1 7% vs. 11 +/- 10%, p=0.07) or to the remaining patients (p=0.06). Both -7/de1(7q) and t(1;22) groups had low CR rates (50%) and poor surviva l. Cytogenetic analysis identifies clinically distinct subsets of chil dhood AML and is useful in tailoring treatment for these patients. Fav orable cytogenetic groups (t(15;17), inv(16), and t(9;11)) may do well with current therapy protocols, whereas unfavorable groups (t(11q23), t(8;21), -7/de1(7q), and t(1;22)) require more effective therapies.