Cytogenetic studies in blast crisis of Ph-positive chronic granulocytic leukemia: results and prognostic evaluation in 52 patients.

Bone marrow cytogenetic (G-banding) studies were carried out in 52 patients with Ph-positive chronic granulocytic leukemia (CGL) at the time of diagnosis of blast crisis. In all cases, the Ph chromosome was due to the standard (9;22) translocation. Eighteen patients displayed the 46,Ph cell line unchanged, whereas additional chromosome abnormalities were observed in the remaining 34 patients (65.4%). Among the latter, numerical karyotypic changes were found in 31 patients and structural changes in 8 patients. Five patients displayed numerical and structural changes simultaneously. The most common chromosome numerical changes were an extra #8 (14 cases) and additional Ph chromosomes (11 patients); an i(17q) was the most frequently observed structural change (3 cases). These three aberrations were often combined; at least one of them was present in 21 patients, constituting 62% of the cases with new cytogenetic abnormalities at blast crisis. When comparing the clinical and hematologic characteristics, as well as the survival, of patients retaining the unchanged 46,Ph cell line and patients showing additional chromosome changes, no differences were found between the two groups of patients. However, a minority displaying a hypodiploid modal chromosome number survived significantly longer than the remaining patients.