Banded chromosome analysis in patients with treatment-associated acute nonlymphocytic leukemia.

We have analyzed G-banded metaphase chromosomes from 20 patients with treatment-associated acute nonlymphocytic leukemia (t-ANLL). Nine patients were previously treated for hematologic malignancies and 11 for solid tumors. The interval from initial therapy to t-ANLL ranged from 35 to 182 mo (median 75.5 mo). Medial age at diagnosis of t-ANLL was 58.5 years. Clonal chromosome abnormalities were found in 19 patients (95%). Loss or partial deletion of the long arm of chromosomes #5 and/or #7 were most common, occurring in nine patients. These abnormalities were associated with hypodiploid complex karyotypes. Other nonrandom abnormalities recurring among karyotypes with abnormalities of chromosome #5 included loss of one #18, partial deletion of the long arm of chromosome #2, ring chromosomes, and a Philadelphia (Ph1) chromosome. We also identified a group of five patients whose only karyotypic abnormality was addition of whole chromosomes. The remaining five patients had other karyotypic abnormalities, the most common of which were structural rearrangements in a pseudodiploid clone. Combined data from our study and the three previously published large series of patients with t-ANLL studied with banding suggest a relationship between karyotype and intensity of prior therapy, with abnormalities of chromosomes #5 and #7 occurring more often in the intensively treated patients.