Prognostic and biological importance of chromosome findings in acute lymphoblastic leukemia.

At least 25 structural chromosomal abnormalities are now found in acute lymphoblastic leukemia (ALL). Many of the abnormalities are associated with particular clinical or blast cell features. Chromosomal translocation breakpoints in ALL are among those that define regions of the genome of oncogenic potential, the recognition of which has led to an improved understanding of the mechanisms of leukemogenesis. The prognostic importance of chromosome findings in ALL concerns demonstration of long-term survival in patients with high hyperdiploid leukemic clones and identification of patients with certain translocations who are at high risk of treatment failure and for whom alternative therapy such as bone marrow transplantation may be desirable. This review summarizes the more recent chromosomal findings in childhood and adult ALL and discusses how increasing recognition of structural change and adoption of alternative therapy for high-risk chromosomal groups may change the prognostic role of cytogenetics in this type of leukemia.