Clinical significance of chromosome abnormalities in childhood acute lymphoblastic leukemia in Japan.

Of 240 Japanese children with acute lymphoblastic leukemia (ALL) treated between 1983 and 1990, 75 (31%) had normal diploidy, 47 (20%) hyperdiploidy with more than 50 chromosomes, 18 (8%) hyperdiploidy with 47-50 chromosomes, 77 (32%) pseudodiploidy, 22 (9%) hypodiploidy and one hypotetraploidy in the leukemic cells. Event-free survival (EFS)±standard error (SE) at 4 years was 74±7% in patients with hyperdiploidy >50, 68±6% in those with normal diploidy, 55±13% in those with hyperdiploidy 47-50, 54±11% in those with hypodiploidy, and 22±5% in those with pseudodiploidy (log-rank, p<0.0001). Seventy-four patients with translocation and 166 patients without translocation had EFS±SE of 26±6% and 64±4%, respectively, at 4 years (p<0.0001)