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

Purpose: To assess the value of initial peripheral blast count in patients with acute lymphoblastic leukemia (ALL) and prednisone good response (PGR). Patients and Methods: 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/muL and a prednisone poor response (PPR) as a blast count of at least 1,000/muL, both in peripheral smears, after 7 days of oral prednisone (60 mg/m(2) 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/muL at diagnosis and those with at least 1,000 blasts/muL at diagnosis. Results: 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/muL and 223 (66%) had an initial blast count of at least 1,000/muL. 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. Conclusions: 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/muL 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.