Prognostic significance of additional cytogenetic abnormalities at diagnosis of Philadelphia chromosome-positive chronic granulocytic leukemia.

Of 661 patients with Philadelphia chromosome (Ph)-positive, nonblastic chronic granulocytic leukemia, 58 had cytogenetic abnormalities in addition to the Ph at the time of diagnosis. Twenty patients had reduplication of the Ph in one or more metaphases. Twenty-one patients with a single Ph exhibited hyperdiploidy in one or more metaphases. Eleven patients had two or more hypodiploid metaphases as their only numerical abnormality. The remaining six patients had a variety of abnormalities. Many patients had more than one type of abnormality. Survival of patients in the different subgroups was similar, but these 58 patients had a shorter course than the 603 patients without additional cytogenetic abnormalities (P less than .02). Survival curves for the two populations did not diverge until the 2-year point, after which the annual death rate among patients with additional cytogenetic abnormalities was approximately 40% higher than that of patients without such abnormalities. The two populations had similar relative risk values according to a hazard ratio formula previously described by the International CGL Prognosis Study Group. Thus, they would have been expected to have essentially identical survival curves. We conclude that the presence of additional cytogenetic abnormalities at the time of diagnosis constitutes an independently significant prognostic feature with an unusually delayed influence on survival.