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). The overall prognosis of our patients was comparable to that of the patients mainly treated in the late 1970s and reported by the Sixth International Workshop on Chromosomes in Leukemia, but was much poorer than that of the patients more recently treated and reported from some American institutions. These findings may possibly reflect less appropriate chemotherapy having been applied to Japanese children with ALL.