IN B-CELL CHRONIC LYMPHOCYTIC-LEUKEMIA CHROMOSOME-17 ABNORMALITIES AND NOT TRISOMY-12 ARE THE SINGLE MOST IMPORTANT CYTOGENETIC ABNORMALITIES FOR THE PROGNOSIS - A CYTOGENETIC AND IMMUNOPHENOTYPIC STUDY OF 480UNSELECTED NEWLY-DIAGNOSED PATIENTS

Of 560 consecutive, newly diagnosed untreated patients with B CLL subm itted for chromosome study, G-banded karyotypes could be obtained in 4 80 cases (86%). Of these, 345 (72%) had normal karyotypes and 135 (28% ) had clonal chromosome abnormalities: trisomy 12 (+12) was found in 4 0 cases, 20 as +12 alone (+12(single)), 20 as +12 with additional abno rmalities (+12(complex)). Other frequent findings included abnormaliti es of 14q, chromosome 17, 13q and 6q. The immunophenotype was typical for CLL in 358 patients (CD5(+), Slg(weak), mainly FMC7(-)) and atypic al for CLL in 122 patients (25%) (CD5(-), or Slg(strong) or FMC7(+)). Chromosome abnormalities were found significantly more often in patien ts with atypical (48%) than in patients with typical CLL phenotype (22 %) (P < 0.00005). Also +12(complex), 14q+, del6q, and abnormalities of chromosome 17 were significantly more frequent in patients with atypi cal CLL phenotype, whereas +12(single) was found equally often in pati ents with typical and atypical CLL phenotype. The cytomorphology of mo st of the +12 patients was that of classical CLL irrespective of pheno type. In univariate survival analysis the following cytogenetic findin gs were significantly correlated to a poor prognosis: chromosome 17 ab normalities, 14q+, an abnormal karyotype, +12(complex), more than one cytogenetic event, and the relative number of abnormal mitoses. In mul tivariate survival analysis chromosome 17 abnormalities were the only cytogenetic findings with independent prognostic value irrespective of immunophenotype. We conclude that in patients with typical CLL immuno penotype, chromosome abnormalities are somewhat less frequent at the t ime of diagnosis than hitherto believed. +12(single) is compatible wit h classical CLL, and has no prognostic influence whereas chromosome 17 abnormalities signify a poor prognosis. In patients with an atypical CLL immunophenotype, chromosome abnormalities including +12(complex), 14q+, del 6q and chromosome 17 are found in about 50% of the patients, and in particular chromosome 17 abnormalities suggest a poor prognosi s. (C) 1997 Elsevier Science Ltd. All rights reserved.