FREQUENCY AND CLINICAL-SIGNIFICANCE OF CYTOGENETIC ABNORMALITIES IN PEDIATRIC T-LINEAGE ACUTE LYMPHOBLASTIC-LEUKEMIA - A REPORT FROM THE CHILDRENS CANCER GROUP

Purpose: Nonrandom chromosomal translocations are frequently observed in pediatric patients with acute lymphoblastic leukemia (ALL). Specifi c translocations, such as t(4;11) and t(9;22), identify subgroups of B -lineage ALL patients who have an increased risk of treatment failure, The current study wets conducted to determine the prognostic signific ance of chromosomal translocations in T-lineage ALL patients, Material s and Methods: The study included 169 children with newly diagnosed T- lineage ALL enrolled between 1988 and 1995 on risk-adjusted protocols of the Children's Cancer Group (CCG) who had centrally reviewed cytoge netics data, Outcome analyses used standard life-table methods. Result s: Presenting features for the current cohort were similar to those of concurrently enrolled patients for whom cytogenetic data were not acc epted on central review, The majority of patients (80.5%) were assigne d to CCG protocols for high-risk ALL and 86.4% had pseudodiploid (9 = 80) or normal diploid (9 = 66) karyotypes; modal chromosome number was not a significant prognostic factor, Overall, 103 of 169 (61%) patien ts had an abnormal karyotype, including 31 with del(6q), 29 with 14q11 breakpoints, 15 with del(9p), 11 with trisomy 8, nine with 11q23 brea kpoints, nine with 14q32 translocations, and eight with 7q32-q36 break points. Thirteen patients had the specific 14q11 translocation t(11;14 )(p13;q11) and all were classified as poor risk, Patients with any of these translocations had outcomes similar to those with normal diploid karyotypes,Conclusion: Chromosomal abnormalities, including specific nonrandom translocations, were frequently observed in a large group of children with T-lineage ALL, but were not significant prognostic fact ors for this cohort. Thus, contemporary intensive treatment programs r esult in favorable outcomes for the majority of T-lineage ALL patients , regardless of karyotypic abnormalities, and such features do not ide ntify patients at higher risk for relapse. (C) 1998 by American Societ y of Clinical Oncology.