Age and acute myeloid leukemia

Abstract

We conducted a retrospective analysis of 968 adults with acute myeloid leukemia (AML) on 5 recent Southwest Oncology Group trials to understand how the nature of AML changes with age. Older study patients with AML presented with poorer performance status, lower white blood cell counts, and a lower percentage of marrow blasts. Multidrug resistance was found in 33% of AMLs in patients younger than age 56 compared with 57% in patients older than 75. The percentage of patients with favorable cytogenetics dropped from 17% in those younger than age 56 to 4% in those older than 75. In contrast, the proportion of patients with unfavorable cytogenetics increased from 35% in those younger than age 56 to 51% in patients older than 75. Particularly striking were the increases in abnormalities of chromosomes 5, 7, and 17 among the elderly. The increased incidence of unfavorable cytogenetics contributed to their poorer outcome, and, within each cytogenetic risk group, treatment outcome deteriorated markedly with age. Finally, the combination of a poor performance status and advanced age identified a group of patients with a very high likelihood of dying within 30 days of initiating induction therapy. The distinct biology and clinical responses seen argue for age-specific assessments when evaluating therapies for AML.

Figure 1.

Southwest Oncology Group Leukemia Committee percentage of patients in cytogenetic risk groups by age category. The percentage includes only patients with a known cytogenetic risk group.

Figure 2.

OS by age for patients with unfavorable risk cytogenetics. Patients younger than 56 years (n = 108) had a median survival of 11 months, patients aged 56 to 65 years (n = 70) had a median survival of 5 months, and patients aged 66 to 75 years (n = 78) had a median survival of 4 months, as did the 27 patients older than 75 years.

Figure 3.

OS by age for patients with intermediate risk cytogenetics. Patients younger than 56 years (n = 149) had a median survival of 26 months, patients aged 56 to 65 years (n = 101) had a median survival of 12 months, patients aged 66 to 75 years (n = 110) had a median survival of 8 months, and patients older than 75 years (n = 24) had a median survival of 7 months.

Figure 4.

OS by age for patients with favorable risk cytogenetics. The median overall survival for patients younger than age 56 (n = 51) and those aged 56 to 65 (n = 10) has not been reached, while the median survival for those older than age 65 (n = 12) was 12 months.