Cytogenetics

Older adults with AML have a lower incidence of favorable chromosomal abnormalities and a higher incidence of unfavorable abnormalities compared to younger adults with AML.12-14 In an analysis of outcome of 1213 adult patients with de novo AML assigned varying doses of postremission therapy, only 2% of older patients (>60 years) had the favorable t(8;21), compared to 9.4% of younger patients (<60 years). Similarly, 3.4% of older patients had inv(16) or t(16;16) compared to 10.4% of younger patients.15 At the opposite end of the spectrum, with respect to unfavorable cytogenetics, 9.1% of older adults had the —7 abnormality compared to 3.2% of younger adults; 6.2%

of older adults had the +8 abnormality compared to 4% of younger adults; and 18.3% of older AML patients had complex cytogenetics (defined as three or more cytogenetic abnormalities, not including core-binding factor cytogenetics) compared to only 7.1% of younger patients. Looking specifically within a population of older adults with AML, an analysis of 1065 older patients with de novo and secondary AML enrolled in the Medical Research Council (MRC) AML 11 trial (in which patients were randomized to one of three remission induction regimens and further randomized to postremission therapy) found that 4% of patients had a t(15;17), 2% had a t(8;21), and only 1% had inv(16). Patients fortunate enough to have one of these abnormalities had a survival advantage over other patients. Poor-risk cytogenetics included a complex karyotype (defined here as five or more abnormalities), which was found in 14% of patients, a +8 abnormality in 10% of patients, a —7 abnormality in 8%, a del(5q) in 8%, and — 5 abnormality in 5% of older AML patients.13

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