Significance of non-standard Philadelphia chromosomes in chronic granulocytic leukaemia

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Abstract
Unselected and similarly treated patients (119) with Ph1-positive chronic granulocytic leukemia (CGL) had the precise nature of their chromosome rearrangements producing the Ph1 studied to determine whether this had any clinical relevance. Eighteen (15%) did not have the usual 9/22 translocation and these, by life-table analysis, had a significantly shorter benign phase of their disease than the others (P < 0.01). Possession of a non-standard Ph1 was related to age, in that whereas only 24 patients were over 60 yr old at diagnosis, 9 (33%) had a non-9/22 translocation (P < 0.01). As the duration of the benign phase seemed to be shorter in those over 60 yr old irrespective of Ph1 type (P < 0.01), the question arose whether non-standard PhI chromosomes were simply occurring in older patients or whether they were affecting prognosis independently. Their independent effect was suggested by the 11 patients under 60 yr old with a non-9/22 Ph1 who still had a significantly shorter benign phase than the 84 of similar age with a standard Ph1 (P < 0.01). The myeloid karyotype can provide prognostic and diagnostic information in patients with CGL.