| Abstract: |
Purpose: Leukemic cells from T-lineage acute lymphoblastic leukemia (ALL) patients are thought to originate from T-lymphocyte precursors corresponding to discrete stages of T-cell ontogeny. Here we sought to determine the influence of leukemic cell apparent maturational stage on treatment outcomes in pediatric T-lineage ALL. Patients and Methods: From 1983 through 1993, 407 pediatric T-lineage ALL patients were enrolled onto two sequential series of risk-adjusted treatment protocols of the Children's Cancer Group. In the current analysis, T-lineage ALL patients were immunophenotypically classified as follows: CD7(+)CD2(-)CD5(-) pro-thymocyte leukemia (pro-TL), CD7(+)(CD2 or CD5)(+)CD3(-) immature TL, and CD7(+)CD2(+)CD5(+) CD3(+) mature TL. Results: Similar induction outcomes of 91.4%, 97.1%, and 98.3% were obtained by the pro-, immature, and mature TL groups, respectively, Four-year event-free survival (EFS) was lower for pro-TL patients (57.1%; SD = 8.4%,) compared with immature and mature TL patients (68.5%; SD = 3.5%; and 77.1%; SD = 4.0%, respectively) with an overall significance of .05 (log-rank test) or .04 (log-rank trend test), Relative hazards rates (RHR) were 2.11 and 1.22 far pro-TL and immature TL versus mature TL, respectively, Highly significant differences were found for overall survival (P = .005, log-rank test; P = .009, log-rank trend test), Multivariate analysis confirmed that the prognostic influence of ontogeny grouping was independent of that of other prognostic factors, Conclusion: Leukemic cells of the pro-TL maturation stage identify a small subgroup of T-lineage ALL patients who have a significantly worse EFS outcome than patients whose cells are of a more mature stage of development. (C) 1997 by American Society of Clinical Oncology. |
