Childhood acute lymphoblastic leukemia: prognostic value of initial peripheral blast count in good responders to prednisone.

Abstract

To assess the value of initial peripheral blast count in patients with acute lymphoblastic leukemia (ALL) and prednisone good response (PGR). From January 1990 to December 1995, 403 consecutive patients with newly diagnosed ALL were enrolled in the authors' protocol 1-ALL90-BFM/HPG. Prednisone good response was defined as a blast count of less than 1,000/microL and a prednisone poor response (PPR) as a blast count of at least 1,000/microL, both in peripheral smears, after 7 days of oral prednisone (60 mg/m2 per day) and one intrathecal dose of methotrexate. In the PGR group, patients were divided into two subgroups: patients who had less than 1,000 blasts/microL at diagnosis and those with at least 1,000 blasts/microL at diagnosis. Three-hundred thirty-seven patients (90%) had PGR and 37 had (10%) PPR. At 5-year follow-up, event-free survival estimates were 67 +/- 3.8% and 38 +/- 8% for PGR and PPR, respectively (P = 0.0001). In the PGR group, 114 patients (34%) had an initial blast count of less than 1,000/microL and 223 (66%) had an initial blast count of at least 1,000/microL. The authors compared the clinical and laboratory characteristics of these subgroups at diagnosis and outcome and detected significant differences in white cell count, incidence of T immunophenotype, and presence of mediastinal or spleen enlargement. However, there were no differences in response to induction treatment, death in complete remission, relapses, or event-free survival probability. In the PGR group, regardless of the initial blast count, both subgroups had the same outcome. The PGR group with an initial blast count of at least 1,000/microL had significantly higher white cell counts. T markers, and mediastinal or spleen enlargement at diagnosis. Response to prednisone is a practical, inexpensive, and good prognostic factor in childhood ALL.