Complex Karyotype in Patients with Chronic Lymphocytic Leukemia.

Chronic Lymphocytic Leukemia (CLL) is heterogeneous and there are two clinical forms with different outcome, in which initial stage and parameters of tumor burden, expression of CD38 and /or ZAP 70, chromosome abnormalities such as 11q23 and 17p13 are associated with a more aggressive course of disease.

The aim of this study is to analyse clinical and biological characteristics and outcome of patients with complex karyotype, and to asses if there are differences with other genomic aberrations.

Fifty patients diagnosed of CLL between 1980 and 1994 were studied (median age: 71 yrs; female/male: 18/32; median follow up 6.6 yrs.). Biological studies with flow cytometry and fluorescence in situ hybridization were done on cryopreserved blood cells. Clinical stages at diagnosis were: Rai stage 0: 56%; I: 20%; II: 16%; III: 6%; IV: 2%. Binet A: 72%; B: 20%; C: 8%. At the time of diagnosis 37% of patients needed treatment and 61% presented disease progression. At the time of this study, 10% of patients are alive with a median follow up of 15.3 yrs.

Seven patients (28%) presented complex karyotype. At the time of diagnosis 43% patients needed treatment and clinical stages were: Rai stage O: 29%, I: 14%, II: 43%, III: 14%, IV: 0%. Binet A: 43%; B: 43%; C: 14%. Median overall median survival was 72 months.

The most frequent genomic aberrations associated with complex karyotype were: del (17p13) and trisomy 12 (60 %). Cellular expression of CD38 and ZAP 70 was not able to separate this group.

Compared with other chromosome abnormalities, there were not important differences in clinical stage at diagnosis or expression of CD38 or ZAP 70, but overall median survival could distinguish three groups: del 11q22-23 or del 17p13 (34 months, p < 0,05) complex karyotype (72 months), and trisomy 12 or del 13q14 (79 months, p > 0,05).

In conclusion, complex karyotype is frequently formed by del 17p13 and trisomy 12 and identifies a subgroup of patients with better prognosis compared with isolated p53 deletion. More studies have to be realized to determine if trisomy 12 is a cell defence mechanism.