Ph-like Acute Lymphoblastic Leukemia in Older Adults

Ph-like Acute Lymphoblastic Leukemia in Older AdultsTo the Editor: In their article on Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) in children, adolescents, and young adults, Roberts and colleagues (Sept.11 issue) 1 note that the frequency of Ph-like ALL in older adults is currently unknown.We analyzed Affymetrix gene-expression profiles of 204 B-cell precursor ALL specimens obtained from 92 adolescents and young adults (16 to 39 years of age), 45 adults (40 to 55 years of age), and 67 older adults (56 to 84 years of age) who received treatment in German Multicenter Study Group for Adult ALL trials according to published algorithms. 2 In contrast to the incidence of Ph-positive ALL, which is known to continually increase with age, 3 the incidence of Ph-like ALL is highest among adolescents and young adults who have B-cell precursor ALL (19 to 27%).Our data showed that the incidence of Ph-like ALL decreased significantly with more advanced age, forming a bell-shaped curve (P = 0.03 by a twotailed Fisher's exact test for the comparison of the incidence among adolescents and young adults with the incidence among adults and older adults) (Fig. 1).Thus, our study independently validated the data in the study by Roberts et al. regarding the incidence of Ph-like ALL among adolescents and young adults and provides evidence of the frequency of this subtype in older patients.Data are lacking to determine whether Ph-like ALL is associated with inferior outcomes and specific genetic alterations in older patients.