Cytogenetic analysis was made at diagnosisin 174 cases of ALL (101 children less than 20 years and 73 adults), excluding Burkitt's ALL (L3). In 11 children (1 1 per cent) insufficient material was obtained. In the remaining 90, 50 (56 per cent) had a normal karyotype, 20 (22 per cent) a hyperdiploid karyotype, five (6 per cent) a hypodiploid karyotype, 12 (1 3 per cent) had a translocation (including seven cases oft( 1; 19)) and three had a pseudodiploid karyotype without translocation. Ninety-eight per cent of patients reached complete remission (CR). Median actuarial CR duration was not attained, was 50 months, 13 months and 11 months respectively in patients with hyperdiploid, normal, hypodiploid karyotype and in patients with a translocation, the difference between subgroups being significant. In a Cox model, cytogenetics were the strongest factor predicting CR duration (p = 0.03) followed by leukocytes (p =0.04), whereas the presence of 'bulky disease' had a borderline value (p=0.077). Of note was that 9/17 (53 per cent) patients with a hypodiploid karyotype or a translocation had no 'risk factors' before cytogenetic analysis.
In adults, cytogenetic analysis was unsuccessful in 15 (20 per cent) of patients. In the remaining 58 cases, (33 per cent) had a normal karyotype, IS (26 per cent) had a hyperdiploid, one (2 per cent) had a hypodiploid karyotype, 19 (33 per cent) had a translocation (including 12 t(9;22)), and four (7 per cent) had a pseudodiploid without translocation. 73 per cent patients reached CR. Median actuarial DFS was 12.5 months. No significant differences in CR rate and CR duration were seen between cytogenetic groups, but median CR duration was slightly longer in patients with a normal karyotype (17 months) and shorter in patients with t(9; 22) (8.5 months). Only 3/12 of the latter had major risk factors before cytogenetic analysis. Cytogenetic analysis is important in ALL, especially in patients with otherwise standard risk factors, as it may reveal unexpected translocations or hypodiploidy, which may require a therapeutic reinforcement.