Racial differences in the survival of childhood B-precursor acute lymphoblastic leukemia: A pediatric oncology group study

Purpose: We conducted a historic cohort study to test the hypothesis that, alter adjustment for biologic factors, African-American (AA) children and S panish surname (SS) children with newly diagnosed B-precursor acute lymphob lastic leukemia had lower survival than did comparable white children. Patients and Methods: From 1981 ta 1994, 4,061 white, 518 AA, and 507 SS ch ildren aged 1 to 20 years were treated on three successive Pediatric Oncolo gy Group multicenter randomized clinical trials. Results: AA and SS patients were more likely to have adverse prognostic fea tures at diagnosis and lower survival than were white patients. The 5-year cumulative survival rates were (probability +/- SE) 81.9% +/- 0.6%, 68.6% /- 2.1%, and 74.9% +/- 2.0% for white, AA, and SS children, respectively. A djusting for age, leukocyte count, sex, era of treatment, and leukemia blas t cell ploidy, we found that AA children had a 42% excess mortality rate co mpared with white children (proportional hazards ratio [PHR] = 1.42; 95% co nfidence interval [CI], 1.12 to 1.80), and SS children had a 33% excess mor tality rate compared with white children (PHR = 1.33; 95% CI, 1.19 to 1.49) . Conclusion: Clinical presentation, tumor biology, and deviations from presc ribed therapy did not explain the differences in survival and event-free su rvival that we observed, although differences seem to be diminishing over t ime with improvements in therapy. The disparity in outcome for AA and SS ch ildren is most likely related to variations in chemotherapeutic response to therapy and not to compliance. Further improvements in outcome may require individualized dosing bared on specific pharmacogenetic profiles, especial ly for AA and SS children. (C) 2000 by American Society of Clinical Oncolog y.